女牙醫稱做過多手術傷關節　衞生署被裁定須賠償2080萬 ...

1. This is an action for damages for personal injuries brought by the plaintiff, Ms Yeung Lai Ping. She was formerly employed by the Department of Health of the Hong Kong Government as a dental officer. She claims damages for injuries to her dominant right wrist, including an attrition injury to the triangular fibrocartilage complex (“TFC”), which put an end to her dental career. She alleges that the injuries to her right wrist were caused by the excessive workload that she was put under while working in the Oral Maxillofacial Surgery and Dental Unit (“OMS&DU”) of the North District Hospital (“NDH”).

2. The plaintiff was born on 19 December 1966. She graduated from the Dental School of the University of Hong Kong in January 1990. She then practised as a dentist in a private dental clinic for 4 and a half years, until September 1994, when she resumed full time studies at the University of Hong Kong to pursue a 2-year Master of Dental Surgery degree which she completed in September 1996. During that period, she also took up the post of a Postgraduate Dental Officer, performing clinical dental work in the Prince Philip Dental Hospital.

3. After completing her Masters’ degree, the plaintiff returned to private practice for a few months, and then joined the Department of Health as a Dental Officer in February 1997. She was first deployed to work as a Relieving Dental Officer. She worked in various Government dental clinics for civil servants, and their dependents, as well as in the Lam Tin School Dental Care Services.

4. In March 1998, she took up an attachment post in the OMS&DU of the Queen Elizabeth Hospital (“QEH”). From time to time, she also took up some additional work, on a voluntary basis, at the Department of Health’s Yaumatei evening dental clinic, and received an honorarium for such work. She was posted to work in OMS&DU of NDH in September 1998. After suffering injuries to her right wrist in October 1999, when she was almost 33 years old, she was transferred to work at the School Dental Care Services in the MacLehose Dental Centre in February 2000. She remained in that post until her invalidation from the civil service in August 2004.

5. It is her work in OMS&DU of NDH that is the subject matter of this litigation.

[size=1em]LIABILITY

6. Liability was strongly contested. Whilst prolonged, awkward and forceful movements of the wrist are known to be associated with work-related upper limb disorders, there are no reported cases of attritional TFC damage arising from working as a dentist.

7. A number of witnesses were called to give evidence. The plaintiff give evidence[1] and called a witness, Dr Jackie Lau Wai Ping (“Dr Jackie Lau”)[2], who is a dentist and was a colleague of the plaintiff. The defendant called a number of witnesses: Dr Sunny Tsui Hing Chung (“Dr Sunny Tsui”)[3], the senior dental officer in OMS&DU of NDH from March 1998 to early 2002; Dr Lee Kwing Hong[4], the consultant in charge of all hospitals where the Department of Health had oral maxillofacial surgery and dental units; Dr Wilkie Lui Wai Kay (“Dr Wilkie Lui”)[5], the senior dental officer in OMS&DU of NDH who took up, from March 2016, the same post that Dr Sunny Tsui held; Ms Irene Tai Sau King (“Ms Irene Tai”)[6], a dental surgery assistant who worked in OMS&DU of NDH from 1998 to December 2008; Dr Cham Kwong Man[7], an acting principal dental officer whose duties included occupational health within the dental service of the Department of Health; and Dr Yau Chuen Kam[8], the consultant oral maxillofacial surgeon in charge of the dental service of the Department of Health before he retired in early 2015. The defendant also adduced evidence relating to the quantum of the plaintiff’s claims from Ms Chui Oi Yee[9], a senior executive officer in the Department of Health in charge of appointments, and Ms Lee Chi[10], a senior executive officer in the Department of Health in charge of personnel.

8. The parties’ called their respective experts on liability to give evidence: Ms Tamara James (“Ms James”)[11], an ergonomics director and assistant professor at Duke University, North Carolina, USA, for the plaintiff, and Professor Chetwyn Chan Che Hin (“Professor Chan”)[12], chair professor of the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University, for the defendant. I also received evidence from the parties’ orthopaedic experts on liability, Professor Leung Ping Chung (“Professor PC Leung”)[13] for the plaintiff and Dr Yeung Sai Hung (“Dr Yeung”)[14] for the defendant, in written form, including 2 joint reports[15], the last one dated 1 November 2016.

9. A substantial number of documents, including medical literature, was also adduced by the parties[16].

10. A disturbing feature of this action is that ithas taken so many years to come to trial. The action was started on 25 September 2002, almost 3 years after the injury was suffered in October 1999, but the action only came on for trial on 12 December 2016, some 17 years later. Justice delayed is not only justice denied. Substantial delay impairs the ability of the court to dispense the justice that the parties deserve. Of the 14 witness statements that I received into evidence, only 3 witness statements had been prepared and signed in November and December 2003, the rest having been prepared and signed in 2015 or 2016. As I had remarked during the course of the trial, when parties allow cases to go to sleep for a many years, and then call factual witnesses to speak of events that occurred more than 10 years ago, both sides suffer prejudice. Human memory is such that it is almost impossible for parties to recall matters that happened so long ago that did not personally affect them in a dynamic way. Even if a witness statement was prepared and signed a few years after the events in question, parties would still have great difficulty if, many years later, they were asked to recall matters and events that had been dealt with in the witness statement in a cursory manner[17].

[size=1em]The plaintiff’s work as a dental officer prior to her attachment to North District Hospital

11. The plaintiff’s evidence about work as a dentist prior to attachment to NDH, which I have summarised in §§2 to 4 above, was not seriously challenged[18]. I also accept her evidence, set out in §§3 to 7 of her supplemental witness statement[19], regarding her duties and workload from February 1990 to September 1998. From late March 1998 to late September 1998, the plaintiff was attached to OMS&DU of QEH where her work was evenly distributed between consultations, conservative and periodontic work, and oral surgery. Between April and June 1998, she performed only 21 surgical extractions (“SX”)[20]. From July to September 1998, the number of SX increased to 38, 40 and 28 per month respectively. I accept her evidence that this increase of SX did not cause any symptoms in her right hand and wrist. I accept the plaintiff’s evidence and find that, prior to working at NDH, the plaintiff did not experience any numbness or other symptoms in her right hand and wrist, either from dental work or from any other cause[21].

[size=1em]Difference between surgical and non-surgical extractions

12. A memorandum on the Efficiency Index, an evaluation system for the dental service (general stream) was issued by the consultant dental surgeon (operations) of the Department of Health on 7 April 1995. It was updated on 29 March 1999[22]. Although it did not apply to the oral maxillofacial stream including OMS&DU, the time required to perform a non-surgical extraction and a SXin the OMS&DU and in the general stream would be comparable[23]. The Efficiency Index (“EF”) included revised guidelines for the Efficiency Index Table (“EIT”) that contained, amongst others, the following definitions[24]:

“Oral surgery/oral medicine
29. Extraction refers to any non-surgical extraction of teeth, retained roots, and supernumeraries. There is no need to differentiate teeth extracted under local anaesthesia or without anaesthesia.
30. Surgical extraction refers to flap-raising procedures for the removal of roots, mesiodens, etc.
31. Soft tissue impaction of the “impacted third molar” refers to the surgical removal of third molar without removal of bone. Bony impaction refers to the surgical extraction of third molar with bone removal.”

When the plaintiff was referred to these definitions, sheexplained that SX did not just involve raising of flap but also removal of bone and cutting of teeth, and that 99% of her surgical extractions involved bony impaction[25].

13. Under cross-examination, the plaintiff agreed that non-surgical extractions did not require the use of surgical drills and that they involved the removal of teeth by forceps and dental elevators, without raising of soft tissue flap, or removal of bone, or sectioning of teeth, and without the need for suturing[26]. She could complete a SX in around 40 to 45 minutes during which she would need to use the handheld drill for about 20 to 30 minutes. In addition, she had to use her wrist for other procedures such as injection of anaesthetic, suturing and irrigation. A SX in the operating theatre (“OT”) took a shorter time because the handheld drill there was more efficient[27]. A faster drill, just like a sharp knife, is more efficient: the strain to the wrist during a SX is due to the resistance from the bone and hard tissue, when the drill is faster one can use less force[28]. A non-surgical extraction took between 10 to 15 minutes during which time a minute to 5 minutes would involve repetitive wrist action to extract the teeth. However she performed comparatively fewer non-surgical extractions[29]. SX required continuous exertion of force as opposed to non-surgical extractions which required a short exertion of force to loosen the tooth after which it would be easy to elevate[30]. Using a surgical drill for SX did not reduce the strain on the wrist when compared with non-surgical extractions: the wrist was put under a lot of strain when the drill was used continuously to cut very hard bone and hard teeth substance[31].

14. Dr Lee Kwing Hong personally found that, with the use of a surgical drill, SX demanded less strength than extractions by forceps. A well-maintained surgical drill produced the minimum of vibrations and made SX less tiring[32]. Dr Sunny Tsui was of the opinion that, when properly used, the surgical drill required a minimum amount of force of the wrist which, in his experience, was even less than that required in tooth extractions by forceps[33].

15. It does not assist me to compare the momentary amount of force required to extract a tooth with forceps or elevators and the momentary amount of force required to operate a surgical drill to cut bone or teeth. The force required must depend on the resistance that is met. What is clear is that a non-surgical extraction takes a shorter period of time than a SX. The EIT records the time to be taken for a non-surgical extraction for a single tooth as 1.5 units[34] or 15 minutes, and the time to be taken for a SX as 4 units or 40 minutes, and even 5 units or 50 minutes for a bony distal or horizontal impaction of the 3rd molar[35]. I accept the plaintiff’s evidence that a non-surgical extraction took between 10 to 15 minutes, during which time a minute to 5 minutes would involve repetitive wrist action to extract the teeth; and that a SX would take around 40 to 45 minutes during which time she would need to use the handheld drill for about 20 to 30 minutes. Repetitive wrist action requiring continuous exertion of force over a period of 20 to 30 minutes produced more strain on the wrist then similar action over a period of 5 minutes.

[size=1em]The plaintiff’s work in OMS&DU of NDH

16. The plaintiff was posted to work in OMS& DU of NDH in September 1998. Dr Sunny Tsui was the senior dental officer posted there. The plaintiff worked 5 and a half days a week, with alternative Saturdays off, working from 9 am to 5 pm on Mondays to Fridays and from 9 am to 1 pm on Saturdays. She would start from 8:30 am when she had dental operations in the OT and when she had to make ward rounds. A working day was split into 2 sessions, the morning and the afternoon sessions. From September 1998 to June 1999, she worked in the OT for 2 sessions and in her surgery for 8 to 9 sessions per week. She spent most of her working hours in her clinic, S1[36].

17. Despite some initial confusion, it became reasonably clear, after hearing the evidence of the plaintiff, her witness, Dr Jackie Lau, and Ms Irene Tai[37], that the equipment available for the plaintiff to use in her clinic, S1, was a KaVo surgical unit Model 905 console to which the surgical drill Model No 3610N[38] was attached. I accept the evidence of Ms Irene Tai that the dental unit in S1 was a KaVo surgical unit Model 905 console and not a Kavolus unit[39]. The plaintiff has given evidence that she relied on Ms Irene Tai to provide her with the information of the dental equipment she used, which Ms Irene Tai did shortly after she was transferred out of NDH in early 2000. Dr Jackie Lau, who was asked about these matters, so many years after she was posted to NDH in August 1998 as a relieving dentist for about 6 weeks, was not sure what the model of the console was. However, all were agreed that, unlike the KaVo Model 905 console depicted in the diagram in Bundle F[40], the console used by the plaintiff in S1 did not have a built in irrigation system. Instead, a syringe with saline would be used to irrigate the patient undergoing dental procedures.

18. The OMS&DU of NDH handled cases of referrals from public and private hospitals, and doctors and dentists in public and private practice, as did the OMS&DU of other hospitals. Most of the referred cases required treatment, usually surgical treatment. The nature and complexity of the referrals varied from simple procedures to complex dental surgery under general anaesthesia. Dental surgeries under local anaesthesia were performed at the clinic. Dental surgeriesunder general anaesthesia, or local anaesthesia with intravenous sedation, were performed in the OT[41]. After the initial consultation, usually carried out by Dr Sunny Tsui[42], an appointment would be booked by the clerical assistant for a dental procedure to be carried out on the patient. Although the plaintiff could instruct the clerical assistant to space out the SX, in practice, that did not happen. When she was first posted to NDH, her appointment book was already fully booked for 3 months, and more bookings were being made continuously thereafter [43].

19. In her 2nd supplemental witness statement, the plaintiff produced a table of SX per work session during the period she worked in NDH from the end of September 1998 to October 1999[44]. The average number of SX per session was 1.68[45]. The table was compiled from entries that had been made in her monthly returns, the appointment book of her surgery, S1, and the OT records. She was cross-examined extensively on this table[46] and errors in relation to commencement of duty and to days off were rightly pointed out to her. It was also suggested to her that the average number of SX per session from the end of September 1998 to October 1999 was 1.65. I am prepared to accept this figure. Hence, I need not deal in detail with the evidence of Dr Wilkie Lui[47], who pointed out certain errors regarding commencement of duty and days off and who suggested that the tables prepared from monthly returns, set out in the tables attached to the witness statement Dr Yau Chuen Kam, were more accurate[48]. Dr Yau Chuen Kam[49], the consultant oral maxillofacial surgeon in charge of the dental service of the Department of Health before he retired in early 2015, gave evidence. He explained that the tables, giving a breakdown of the work carried out by the plaintiff and Dr Sunny Tsui[50], and a breakdown of the number of non-surgical extractions and SX performed by the plaintiff and 4 comparable dental officers[51], were prepared painstakingly by the executive staff of the Department of Health by extrapolating them from the monthly returns[52]. I also accept that, if a discrepancy is spotted, that the monthly returns would be more accurate than the appointment book[53]. In the event of conflict between the plaintiff’s tables and Dr Yau Chuen Kam’s tables, I will rely upon the latter as containing the correct information. Although Dr Yau Chuen Kam did not verify the figures set out in his tables[54], I do not see any basis to doubt the accuracy of his tables. I also accept the accuracy of the information set out in the table setting out the source of the information from which the plaintiff’s and the comparable dental officers’ workload was ascertained[55]. Although Dr Yau Chuen Kam’s witness statement was dated 5 June 2012, and was made in response to the plaintiff’s supplemental witness statement dated 3 April 2012[56], the tables he produced were prepared in 2003.

20. I proceed on the basis that the plaintiff’s table is largely accurate and that any minor errors in it do not affect the overall average. The heaviest workload in terms of SX per session was during the months of late September to November 1998 being 2.16, 2.15 and 2.0 SX per session for the 3 months. The workload lessened in the subsequent months from December 1998 to July 1999 but the number of SX per session still ranged from a low of 1.54 in May 1999 to a high of 1.81 in February 1999. It appears from the tables produced by Dr Yau Chuen Kam that, from October 1998 to September 1999, the plaintiff had performed 710 SX whilst, over the same period, Dr Sunny Tsui had only performed 479 SX[57].

21. Dr Jackie Lau gave evidence[58] that she and the plaintiff were in the same batch of colleagues who joined the Department of Health in 1997. She did not know the plaintiff personally but came to know, in 2000, that she suffered from right-hand wrist pain and she mentioned casually to the plaintiff that she had also experienced right-hand wrist pain while working in NDH that was due to the high SX workload. In 2004, she agreed to the plaintiff’s request to her to be a witness in these proceedings. Dr Jackie Lau had been posted to NDH in August 1998 as a relieving dentist for about 6 weeks. She worked 11 sessions per week. Because the booking schedule was very heavy at NDH, she had 3 SX in the morning and 2 SX in the afternoon almost 5 days a week. She started to suffer wrist pain and shoulder discomfort after she had worked for about 2 weeks at NDH. The pain became progressively worse until she was posted elsewhere in mid-September 1998. She did not complain about this to Dr Sunny Tsui. She did not do so because she was just a relieving dentist posted to NDH for several weeks and she believed that the pain would stop when she left NDH. She explained that she was young then and that her generation was not used to speak out at that time. She agreed that, if she was unwell, she, or the receptionist, or the nurse, could cancel an appointment for a dental procedure, but only after seeking approval from the person in charge. I found her to be a frank and candid witness. I accept her testimony and find that she suffered from wrist pain after performing a substantial number of SX during the 6 weeks she spent in NDH. However, given the substantial passage of some 12 years before she made her witness statement in December 2010, I am not satisfied that her memory of being assigned as many as 5 SX to perform every day is reliable.

22. Although Dr Sunny Tsui has no recall of any such conversation[59], I accept the plaintiff’s evidence that, despite her heavy workload, Dr Sunny Tsui still asked her if she could do more SX every day. This occurred before she had any right hand symptoms. She declined to do so and suggested to him that she should be given more consultations, a better rotation of a variety of dental treatments, and space between the bookings for SX. However, he did not respond to her request[60].

23. In late May to early June 1999, the plaintiff felt weakness in her right hand and nocturnal paraesthesia[61]. It also occurred intermittently during the daytime when she was driving. In July 1999, right wrist pain started to occur when she performed dental procedures. An occupational therapist made her a working splint to wear on her right hand in late July or early August 1999. Dr Sunny Tsui knew this and had been told that the splint was made for her by a patient who was an occupational therapist[62]. She first consulted the orthopaedic doctor in NDH on 19 August 1999[63] and was prescribed pain relief medication. At that time, Dr Sunny Tsui was on leave and only returned on 28 August 1999. He has no recollection of being informed about this consultation or a subsequent assessment of the plaintiff for carpal tunnel syndrome on 23 August 1999[64]. I am unable, on the evidence before me, to find that he was informed of these consultations after his return from leave. Occupational therapy and physiotherapy was also provided to the plaintiff. Dr Sunny Tsui knew that she had started physiotherapy but was not sure when she did so[65]. By late September 1999, the increase in the severity of her right wrist pain, especially on exertion, together with her right hand paraesthesia, had made dental work intolerable. She was granted sick leave by the orthopaedic clinic of NDH from 4 October 1999 to 23 October 1999[66].

24. It was the plaintiff’s evidence that the hand splint was conspicuous, that Dr Sunny Tsui knew of her right hand and wrist problems, and that she had sought medical assistance[67]. On the evidence before me, I am able to find that Dr Sunny Tsui noticed her wearing a hand splint in July or August 1999[68] and, further, that he knew that she was granted sick leave for her wrist pain from 4 October 1999 to 23 October 1999, as he had to make arrangements for relieving dental officers[69]. He would have seen the sick leave certificates and would have known its contents stating, in one of them, that she had right hand numbness and weakness, tenderness around right wrist; and, in the other, that she had right wrist pain[70].

25. The plaintiff also gave evidence that when she was back at work after the end of 3 weeks’ sick leave on 23 October 1999, Dr Tsui said to her that her sick leave was hindering and disrupting the unit’s operation and that he would not change the schedule for her, even though the receptionist had requested that less surgical cases be booked for her[71]. In her witness statement made on 13 December 2003, the plaintiff has said that when she was “back at work for short periods between sick leaves, he would not change the schedule for me, even though the receptionist had requested that less surgical cases be booked for me”. Dr Sunny Tsui made no mention of this in his witness statement. It was not put to him, in the course of his evidence, that such a conversation had taken place. If it had been, it is likely that he would have said that he had no recall of such a conversation. I accept the plaintiff’s evidence on this matter, but not the further evidence that she gave, for the first time in the course of her cross-examination, namely, that she had asked Dr Sunny Tsui whether he wished to make her “handicapped”[72], which, she admitted, was not mentioned in any of her witness statements. With the passage of some 17 years, I am not satisfied that her recollection of this conversation is reliable.

26. Dr Lee Kwing Hong was called to give evidence[73]. He was the consultant in charge looking after all hospitals where the Department of Health had an OMS&DU since September 2003. He retired in September 2010. In mid-1998, he was the consultant oral and maxillofacial surgeon at the Prince of Wales Hospital and remained in that post until September 2003. NDH was a newly established hospital in 1998 and Dr Sunny Tsui was a senior medical officer posted to the OMS&DU of NDH. Dr Lee Kwing Hong would visit the OMS&DU of NDH and participate in patient management there in complex cases, together with Dr Sunny Tsui, upon his request. Towards the end of 1999, the plaintiff began to take sick leave for pain in her right hand. He had seen her wearing a splint from time to time. Under cross-examination, he said that the immediate supervisor of Dr Sunny Tsui was Dr Bill Yan, the consultant oral maxillofacial surgeon in charge of NDH at that time. Dr Albert Ho, a consultant in operations, was also responsible for looking after the occupational health of all the staff. He could not comment on whether or not Dr Sunny Tsui should have consulted either Dr Bill Yan or Dr Albert Ho about the plaintiff’s case. His role was to come to NDH and offer his expertise as a consultant in the OT for difficult cases. He was not involved in the staff management of NDH. He had been involved in staff management and personnel management issues from 2003 to 2010. It was not very common, but if a dental officer suffered a wrist injury or had wrist pain then, generally speaking, in the initial period after the completion of sick leave, he would assign less complicated and less strenuous cases to the officer.

27. It was the plaintiff’s evidence that, on her return from sick leave after 23 October 1999, she was initially assigned one SX per day for 4 days and 2 SX on one day whilst Dr Sunny Tsui conducted all the SX fixed in the OT[74]. This is borne out by her appointment book for the week of 25 to 30 October 1999 which shows that 1 SX was fixed for her on Monday, 25 October 1999, 1 SX on the Tuesday, 26 October 1999, 2 SX on Wednesday, 27 October 1999[75], none on Thursday, 28 October 1999, and 1 SX on Friday, 29 October 1999[76]. This was considerably less than her SX workload before she went on sick leave on 4 October 1999, as is shown on the following table:

Mon
Tue
Wed
Thu
Fri
Sat
Total
Aug 30
Closed Aug 31
2 SX Sep 1
2 SX 2
1 SX 3
1 SX 4
Off
6 SX
6
2 SX 7
1 SX 8
4 SX 9
2 SX 10
2 SX 11
0 SX
11 SX
13
2 SX 14
1 SX 15
3 SX 16
Closed (typhoon) 17
2 SX 18
Off
8 SX
20
3 SX 21
1 SX 22
3 SX 23
2 SX 24
1 SX 25
Public Holiday
10 SX
27
2 SX 28
1 SX 29
4 SX 30
1 SX Oct 1
Public Holiday Oct 2
Off
8 SX

I am not able to conclude whether or not the reduction in her SX workload on her return to work on 25 October 1999 was planned, or fortuitous, given that her appointment book was being filled continuously and could be fully booked months in advance. Indeed, the plaintiff accepted that it was likely that appointments for the week commencing 25 October 1999 had been booked before 4 October 1999 when she was given sick leave[77].

28. Notwithstanding that her condition was well known to Dr Sunny Tsui, 3 SX cases had been, and remained, assigned to her to carry out during the Saturday morning session on 30 October 1999. I accept her evidence and find that she performed 3 SX that morning[78], that in the course of those extractions, her right wrist gradually became more painful and that, towards the end of the third case, she suffered excruciating pain in her right wrist[79]. On the following Monday, 1 November 1999, she was granted further sick leave for a few weeks which was subsequently continued until 24 December 1999[80].

29. I accept the plaintiff’s evidence that after her return to work in the week of 25 October 1999, Dr Sunny Tsui had not asked whether she could manage to perform SX and, further, that he had had not asked her whether she could manage to perform 3 SX on the Saturday morning[81]. Indeed, I am unable to find, on the evidence, that Dr Sunny Tsui knew that 3 SX cases had been assigned to her on that morning. As I have found above, her appointment book was being filled continuously and could be fully booked months in advance.

30. Dr Cham Kwong Man[82], an acting principal dental officer whose duties included occupational health within the dental service of the Department of Health, gave evidence and she was asked about the memorandum dated 19 January 2000 from a Mr C M Poon, who was a senior occupational hygienist for the Commissioner for Labour to the Director of Health. The memorandum stated that:

“As one of the purposes of the Occupational Safety and Health Ordinance is to prescribe measures that will contribute to making the workplaces safer and healthier for employees, the following suggestions are made:
• with regard to the work arrangement of [the plaintiff’s] work during her recovery period, it is highly recommended that she should be transferred to less demanding positions that require fewer forceful exertions of the wrist (e.g. posting to the School Dental Care Service) as early as possible.
• The work schedule should be re-arranged so that consecutive surgical wisdom tooth extractions are interspersed with activities that involve fewer repetitive and forceful manual exertions (e.g. consultation work; filling of dental cavities).
• Cases that involve surgical wisdom tooth extractions should be evenly distributed among different dental officers.”

She agreed with the first recommendation. Regarding the second recommendation, she said it was good advice for the injured staff but it might depend on whether that specific clinic or unit could provide for the surgical wisdom tooth extractions to be interspersed with lighter activities. If it could not be done, the first option, i.e. to post out, would be the best one rather than to have impact on the work schedule in that clinic. As regards the third recommendation, she said that if changing the work schedule would cause hardship in the workplace then they would change the operator, by posting out. After it was pointed out to her that the suggestion that the plaintiff be posted out was not made until 22 November 1999, the following question was put to her:

“Court: [Counsel’s] question is that if the plaintiff was already starting to see orthopaedic doctors because of the condition of her right hand and wrist, and was on sick leave, would the best time to offer a posting out be at the time when she has finished her sick leave and was coming back [to work]?
A. I agree.”[83]

[size=1em]The medical evidence on liability

31. As I have noted in §8, I received evidence from the parties’ orthopaedic experts on liability, Professor PC Leung[84] for the plaintiff and Dr Yeung”[85] for the defendant, in written form, including 2 joint reports[86], the last one dated 1 November 2016. They have provided a helpful, and factually correct, history of her medical problem in their joint report dated 14 June 2012, which I set out below[87]:

“2 HISTORY
…
2.7 Around June 1999, she noticed numbness of her right hand and forearm. Initially, it was intermittent e.g. when she was turning the steering wheel while driving. Sometime, numbness woke her up from sleep. By July 1999, she began to have pain around the right wrist when she was performing tooth extraction. She tried to put on a splint on the advice of an occupational therapist but found that it was not useful. She sought treatment from the orthopaedic clinic of NDH from August 1999. Then, symptoms related to carpal tunnel compression of the right median nerve bothered her day and night and she had right wrist pain whenever she performed strenuous dental extraction. Between October and December 1999, she had to take sick leaves and she had problem with activities of daily living such as carrying shopping bags, driving and typing.
2.8 In October 1999, she also sought treatment from the Occupational Health Clinic and light duty was recommended. In January 2000, her posting in NDH ended and she was transferred to look after school children in the Dental Centre in Wanchai. Her main duty was to supervise the work of dental therapists and to assist them in difficult extractions. She recalled that she was unable to cope with this work.
2.9 From November 1999, she sought treatment from Dr So Yat Cheong, consultant orthopaedic surgeon of QEH. MRI of the right wrist was performed for her in August 2000. According to the medical report by Dr YC So, the diagnoses were right carpal tunnel syndrome and right wrist triangular fibrocartilage (TFC) tear. She was treated with splintage, local steroid injection and physiotherapy. However, she had persistent numbness, weakness and pain around the right wrist. Operation was performed for her at QEH in August 2002 to release the carpal tunnel entrapment, repair the TFC and relocate the dislocated Extensor carpi ulnaris tendon.
2.10 After the operation, she used a splint for her right wrist and she tried to use her left hand to extract teeth. But this resulted in pain at the ulnar aspect of the left wrist and also occasional numbness of the left hand.
2.11 In December 2002, about 4 months after the operation, Prof PC Leung examined Dr LP Yeung. Prof Leung reported “her right wrist problems were about 50% resolved, but on strenuous supination/pronation, pain was still felt over the ulnar side of the wrist”.
2.12 In August 2003, about 1 year after the surgery, Dr SH Yeung examined her. At that time, she still had pain at the ulnar aspect of her right wrist, weakness of right hand and also numbness of the right thumb and fingers on the radial side. Dr SH Yeung was of the opinion that she had not reached maximum medical improvement at the stage for both the carpal tunnel syndrome and TFC tear.
2.13 In September 2009, 7 years after the surgery, Prof PC Leung examined her again. According to the reports of Prof Leung dated 9.9.2009 and 18.1.2010, she “experienced some further improvement. The numbness over the right hand was only occasionally felt. The wrist pain would come on strenuous wrist motion, particularly on twisting. Since she stopped her dental practice, her own assessment was that she was somewhat 70% recovered”.
2.14 Dr LP Yeung said that in August 2004, a medical board recommended her to be invalidated because of her right wrist problem and she has retired since.”

32. Dr Yeung had also rightly noted in his earlier report dated 5 September 2003[88] that the plaintiff had symptoms of carpal tunnel entrapment on her non-dominant left hand. She had told him that nerve conduction test done by Dr Chan Yuk Wah in May 2000 showed that the left-hand side was mildly abnormal. The plaintiff also noticed symptoms on the left hand after the right-hand operation in August 2002. At that time, her right hand was bandaged and splinted and she had to use the left-hand for her daily activities. During that time, she was already posted to look after school children and the volume of work was already reduced.

33. In their joint report dated 14 June 2012, Professor PC Leung and Dr Yeung agreed that the plaintiff suffered from bilateral carpal tunnel syndrome that was more severe on the right side and was only transient and mild on the left side; tear of TFC at the right wrist; and dislocation of the extensor carpi ulnaris tendon of the right wrist[89].

34. Their opinion differed on the causation of these injuries. Professor PC Leung was of the opinion that the carpal tunnel syndrome and TFC tear of the right wrist were most likely the result of occupational injuries[90]. Dr Yeung agreed that the dental work might have contributed to the development of right carpal tunnel syndrome. However, the plaintiff also developed symptoms of carpal tunnel entrapment in her non-dominant left hand during the period when she was posted to look after schoolchildren and when the volume of work was already reduced. He was of the view that the plaintiff was intrinsically predisposed to develop carpal tunnel entrapment. Even Professor PC Leung had agreed in his earlier report dated 24 January 2003 that the fact that her non-dominant hand also developed a mild degree of carpal tunnel syndrome within the year after the right hand had problems supported the assumption that the problems in the dominant hand and wrist might not be totally occupation-related[91]. Dr Yeung also agreed that the dental work of the plaintiff might have contributed to the development of TFC injury. X-ray of her right wrist taken in QEH on 31 July 2002 showed that her right ulnar was 1 mm longer than the radius: i.e. she was ulnar positive for 1 mm. Positive ulnar variance of +1 to +5 mm has been reported to be associated with TFC injury. Dr Yeung was of the opinion that the positive ulnar variance was the major factor causing the TFC injury[92].

35. Professor PC Leung and Dr Yeung agreed that there was no known pre-existing problem of carpal tunnel syndrome nor pre-existing condition for TFC injury. However, Dr Yeung was of the opinion that the positive ulnar are variance was a predisposing cause of the TFC injury[93]. Professor PC Leung agreed, in this later report dated 29 February 2016, that although the positive ulnar variance could be considered a predisposing factor, the structural variation could have at most, only made the plaintiff more vulnerable to unfavourable work-related manual stresses. Assumptions that a minor structural variance at the wrist would disable a young working person could not stand reasonable and logical analysis[94].

36. Professor PC Leung and Dr Yeung have clarified and narrowed their difference of opinion on causation in their 2nd joint report dated 1 November 2016[95]. By this time, both of them had the opportunity to review the x-rays of both wrists taken on 11 January 2016. The x-ray of the left wrist showed that ulnar positive variance was 2.3 mm the left side, which was more than the positive variance of 1 mm on the right site[96]. Dr Yeung agreed with Professor PC Leung that her left side with the positive variance of 2.3 mm should be more vulnerable to TFC injury. There were several known predisposing causes of attrition type of TFC injury and positive ulnar variance was just one of them. Frequent use of power group with rotation of the forearm was another factor[97]. Previous research of the forces transmitted through the radius and ulna showed that when they were of equal length (neutral variance), about 20% of the force passes through the ulna. As the length of the ulna increases to +1 mm, the force increases to 30%. When the ulna was +2.5 mm, 41.9% of the force was transmitted through the ulna[98].

37. Professor PC Leung and Dr Yeung were in agreement that the plaintiff’s TFC damage could be the result of both structural predisposition and repeated work-related strenuous mechanical stresses. They would not be able to affirm that her wrist problem was solely predisposed by the structural abnormality. They both felt that repeated mechanical stresses on the wrist and TFC could cause chronic damage, particularly so, because of the structural variance of the plaintiff’s right wrist[99].

38. Dr Yeung was of the opinion that both are ulnar plus variance and repetitive strenuous movements required for her work will predisposing factors of her TFC injury. In his earlier report dated 5 September 2003, Dr Yeung stated that he thought that her work should be responsible for 20% of any impairment arising from the TFC injury[100]. In their 2nd joint report dated 1 November 2016, Dr Yeung clarified that there was no scientifically validated method to apportion her impairment from these 2 factors quantitatively and that, in his previous report dated 5 September 2003, he had “put up the assumption that her work should be responsible for 20% of her impairment only”[101]. Save for noting that the ulnar positive variance of her right wrist was mild, Professor PC Leung refrained from committing a quantitative analysis with regard to the compensation issues[102].

[size=1em]My findings on causation

39. I have already found that the plaintiff performed 3 SX on the morning of 30 October 1999; that, in the course of those extractions, her right wrist gradually became more painful; and that, towards the end of the third case, she suffered excruciating pain in her right wrist[103]. I find as a fact that the plaintiff suffered an attrition fracture of the TFC of her right wrist towards the end of the third SX that she was performing that morning, and that she suffered excruciating pain in her right wrist as a result of the damage done to the TFC of her right wrist. I am supported in making this finding by the joint opinion of Professor PC Leung and Dr Yeung, both of whom were of the opinion that repeated mechanical stresses on the wrist and TFC could cause chronic damage, particularly so, because of the structural variance of the plaintiff’s right wrist.

40. Dr Yeung was of the opinion that her work should be responsible for 20% of any impairment arising from the TFC injury, thereby implying that the structural variance of the plaintiff’s right wrist was 80% responsible for the TFC injury. He conceded, very frankly, that there was no scientifically validated method to make such an apportionment between the 2 causes of the TFC injury. In this connection, I prefer the opinion of Professor PC Leung that the main cause of the TFC injury was the repetitive strenuous activities related to dental extractions and the related wrist movements, and that the minor positive ulnar variance of the right wrist was a minor cause of the TFC injury in that it made the plaintiff more vulnerable to unfavourable work-related manual stresses. I am persuaded by Professor PC Leung to accept that assumptions that a minor structural variance at the wrist would disable a young working person could not stand reasonable and logical analysis[104]. I find that, but for the work-related stresses which she experienced on the morning of 30 October 1999, the plaintiff would not have suffered the TFC injury on that day, a finding which is supported by the opinion of Professor PC Leung, which I have preferred. The strict test of causation in negligence is satisfied in the present case.

41. However, even if I were to accept Dr Yeung’s opinion that her work was 20% to blame for the TFC injury, a 20% contribution towards the damage being caused was significant enough for me to find that her work was a material cause of the TFC injury. A 20% contribution towards the damage being caused cannot be classified as being de minimus[105]. It is trite law that liability attaches in negligence even though the conduct complained of was not the sole or major cause of the damage that was suffered.

42. In BAE Systems (Operations) v Konczak [2017] EWCA Civ 1188; [2018] I.C.R. 1, Underhill LJ commented on the distinction between apportionment of causation and quantification of damage and stated:

“59 The application of the principle expounded in [Rahman v Arearose Ltd [2001] QB 351] in the context of psychiatric injury caused by stress at work was discussed in Hatton v Sutherland [2002] ICR 613. Paragraphs 36–42 of the judgment of the court given by Hale LJ, under the heading “Apportionment and quantification”, summarise and analyse the cases to which I have referred above (also referring to and distinguishing the well-known decisions of the House of Lords in Bonnington Castings Ltd v Wardlaw[1956] AC 613 and McGhee v National Coal Board [1973] 1 WLR 1). At para 41 the court says:
“Hence if it is established that the constellation of symptoms suffered by the claimant stems from a number of different extrinsic causes then in our view a sensible attempt should be made to apportion liability accordingly. There is no reason to distinguish these conditions from the chronological development of industrial diseases or disabilities. The analogy with the polluted stream is closer than the analogy with the single fire.”
60 At para 42 the court goes on to make a distinct point:
“Where the tortfeasor’s breach of duty has exacerbated a pre-existing disorder or accelerated the effect of pre-existing vulnerability, the award of general damages for pain, suffering and loss of amenity will reflect only the exacerbation or acceleration. Further, the quantification of damages for financial losses must take some account of contingencies. In this context, one of those contingencies may well be the chance that the claimant would have succumbed to a stress-related disorder in any event. As it happens, all of these principles are exemplified by the decision of Otton J at first instance in Page v Smith [1993] PIQR Q55 (and not appealed by the claimant: see Page v Smith (No 2) [1996] 1 WLR 855). He reduced the multiplier for future loss of earnings … from 10 to 6 to reflect the many factors making it probable that the claimant would not have had a full and unbroken period of employment in any event and the real possibility that his employers would have terminated his employment because of his absences from work.”
61 The points made at paras 41 and 42 of the judgment are recapitulated in the numbered “practical propositions” which the court propounds by way of summary at para 43 of its judgment: at the end of the paragraph it describes them as “principles”. Proposition 15 is:
“Where the harm suffered has more than one cause, the employer should only pay for that proportion of the harm suffered which is attributable to his wrongdoing, unless the harm is truly indivisible. It is for the defendant to raise the question of apportionment …”
Proposition 16 is:
“The assessment of damages will take account of any pre-existing disorder or vulnerability and of the chance that the claimant would have succumbed to a stress-related disorder in any event.”
62 The distinction between propositions 15 and 16 needs to be appreciated. Proposition 15 is applicable to cases where the injury in question is regarded as having multiple causes, one or more of which are, or are attributable to, the wrongful acts of the employer but one or more of which are not. Proposition 16 applies where the claimant has a pre-existing vulnerability which is not treated as a cause in itself but which might have led to a similar injury (for which the employer would not have been responsible) even if the wrong had not been committed. At the level of deep theory the distinction between pre-existing vulnerability and concurrent cause may be debatable, and even if it is legitimate it may be difficult to apply in particular cases. There may also be cases where both propositions are in play. It may in many or most cases not be necessary for a court or tribunal to worry too much about where exactly to draw the line. Both propositions are tools which enable a tribunal to avoid over-compensation in these difficult cases. Nevertheless they are clearly treated as conceptually distinct.”

43. Even if I were to accept Dr Yeung’s opinion that her work should be responsible for 20% of any impairment arising from the TFC injury, and that the structural variance of the plaintiff’s right wrist was 80% responsible for the TFC injury, I would go on to find that the TFC injury was truly indivisible, and that it is not possible to apportion causation in this case.

44. Finally, even if the ulnar variation was 80% responsible for the TFC damage, the plaintiff’s pre-existing vulnerability did not make her loss too remote as the thin eggshell skull rule applies in this case. A defendant has to take his victim as he finds him or, as Mackinnon LJ stated in Owens v. Liverpool Corp[106]:

“… one who is guilty of negligence to another must put up with idiosyncrasies of his victim that increase the likelihood or extent of damage to him: it is no answer to a claim for a fractured skull that its owner had an unusually fragile one”.

[size=1em]Was the Department of Health in breach of its duty of care owed to its employee, the plaintiff, by requiring her to carry out 3 SX on 30 October 1999?

45. The Department of Health owed a non delegable duty of care to its employee, the plaintiff, to take reasonable steps to safeguard from injury in the course of employment. The plaintiff started to suffer from symptoms in her right wrist in late May and early June 1999. Right wrist pain started to occur when she performed dental procedures in July 1999. She wore a splint on her right hand from late July or early August 1999. Dr Sunny Tsui had noticed her wearing a hand splint at that time. She consulted an orthopaedic doctor in mid-August 1999. She received occupational therapy and physiotherapy. Dr Sunny Tsui knew that she had started physiotherapy although he was not sure when she did so.

46. From 31 August 1999 to 30 September 1999[107], the work that was assigned to perform was considerable, and included 43 SX, despite the fact that she had started to suffer from right wrist pain from late July or early August 1999, had towear a splint, and was prescribed pain relief medication. Notwithstanding that her condition was well known to Dr Sunny Tsui, 3 SX cases had been, and remained, assigned to her to carry out during the Saturday morning session on 30 October 1999 after her return to work from sick leave. Although Dr Sunny Tsui may not have known that 3 SX cases had been assigned to her on that morning, given the condition of her right wrist, she should not have been assigned to perform 3 SX on one morning. The Department of Health, the employer of the plaintiff, is imputed with the knowledge of the condition of the plaintiff’s right wrist that its employee, Dr Sunny Tsui, had, and the Department of Health is also imputed with the knowledge of its employee who had fixed 3 SX on the plaintiff’s appointment book for the plaintiff to perform on 30 October 1999.

47. Dr Lee Kwing Hong gave evidence that if a dental officer suffered a wrist injury or had wrist pain then, generally speaking, in the initial period after the completion of sick leave, he would assign less complicated and less strenuous cases to the officer. Dr Cham Kwong Man agreed that it is highly recommended that a dental officer returning to work after injury should be transferred, during her recovery period, to less demanding positions that require fewer forceful exertions of the wrist and added that if changing the work schedule to accommodate the dental officer during her recovery period would cause hardship in the workplace, then they would post out the recovering dental officer. She also agreed that the best time to offer a posting out would be at the time when the dental officer had finished her sick leave.

48. I refer to the literature and the evidence I referred to in §§114-116 below. I find that the defendant knew or ought to have known that repetitive strenuous dental activities related to wrist movements could cause upper limb musculo-skeletal disorders in dental personnel, including carpal tunnel syndrome. I find that it was reasonably foreseeable that assigning the plaintiff to perform 3 SX on the morning of 30 October 1999 may cause damage to her right wrist which had been injured previously. If damage to the wrist is reasonably foreseeable, reasonable foresight of the extent of damage is not required for liability to attach in negligence, neither is reasonable foresight of TFC damage to the wrist required, nor is reasonable foresight of the precise manner of its infliction required, for liability to attach in negligence [108].

49. I am satisfied that the Department of Health is liable in negligence to the plaintiff for attrition fracture of the TFC of her right wrist that she suffered on 30 October 1999. The Department of Health was in breach of its duty of care owed to its employee, the plaintiff, by requiring her to carry out 3 SX on 30 October 1999. The breach of the said duty of care caused the TFC damage to her right wrist.

[size=1em]Contributory negligence

50. The plaintiff was cross-examined extensively on what steps she took to reduce the workload that had been fixed for her for Saturday, 30 October 1999[109]. I am satisfied that she would have seen, even before Friday, 29 October 1999, that she was scheduled to perform 3 SX on the Saturday morning. I am also satisfied that she did not complain to Dr Sunny Tsui that she could not handle 3 SX in 1 session. However, I accept her evidence that the staff of NDH did try to cancel some of her appointments so that she would not have to shoulder that much work[110]. An appointment for a SX on the afternoon of Wednesday, 27 October 1999, had been cancelled and there were 3 other cancellations, for other procedures, on Monday, 25 October 1999,on Thursday, 28 October 1999, and on Friday, 29 October 1999[111]. She acknowledged that she was worried about having to perform 3 SX on the Saturday morning. However, she expected some changes to be made to the Saturday appointments[112]. I find that this was more a hope on her part, rather than an expectation.

51. Insofar as this line of cross examination was directed to trying to establish contributory negligence on the part of the plaintiff, it is important to note that the onus is on the defendant to establish that any steps that the plaintiff ought to have taken to reduce her workload would have resulted in the rescheduling of some of her appointments on that Saturday morning. I am not satisfied, on the evidence, that any complaints the plaintiff ought to have made would have resulted in the rescheduling of the appointments fixed for that Saturday morning. Indeed, a stronger ground for asserting contributory negligence on the part of the plaintiff would be to rely upon the plaintiff’s failure to have regard to our own safety, by her failure to stop work and to refuse to carry out the third SX fixed for that morning after her wrist gradually became more painful in the course of the SX she performed; and to assert that, had she done so, the injury to her TFC would not have occurred[113]. Dr Cham Kwong Man’s evidence that an employee, who is a graduated dentist, has his individual responsibility to take care of himself when performing his duty, for example, by applying what he has learned in dental school when extracting teeth, is a layman’s restatement, in the context of dental work, of the general duty imposed by the law of negligence to take care of one’s own safety[114]. However, these observations are academic as these matters were not pleaded in the Defence to the plaintiff’s claims. The plaintiff’s failure to complain about 3 SX that had been fixed on that Saturday morning was raised in the course of final submissions[115], but was rightly objected to[116], as this ground had not been included under the particulars of the plaintiff’s contributory negligence pleaded in the Defence.

52. The matters that were pleaded were not pursued at trial[117]. The offer to be posted out of NDH was only made on 22 November 1999, after the damage to the TFC of her right wrist had already occurred[118].

[size=1em]The ergonomic evidence

53. Ms James[119], an ergonomics director and assistant professor at Duke University, North Carolina, USA, gave evidence for the plaintiff, and Professor Chan[120], Chair Professor of the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University, gave evidence for the defendant. As I have already found the Department of Health liable in negligence for the reasons set out above, I shall deal with this evidence and my findings on them as briefly as possible. I do so as they would become relevant if I am overturned, on appeal, on the findings I have made above.

54. Ms James is an assistant professor in the Department of Community and Family Medicine at Duke University Medical Center. She is a certified professional ergonomist who received her master’s degree in Human Factors Engineering from George Mason University in Virginia. Her bachelor’s degree is in the area of Industrial Engineering from the University of Iowa. Ms James has worked for over 20 years as the Director of Ergonomics Program at Duke University Medical Center, having responsibility for hazard evaluation and training for upward of 35,000 workers[121]. Ms James prepared her ergonomic assessment in this case based on the Moore and Garg Strain Index. In 1995, J Stephen Moore and Arun Garg published a paper called “The Strain Index: a Proposed Method to Analyse Jobs for Risk of Distil Upper Extremity Disorders.”[122] (“the Strain Index”). Prior to this case, Ms James had performed ergonomic assessments on dentists, some of whom had hand and wrist related issues[123]. In her ergonomic assessments, she had used the Strain Index about 25 times. Although the Strain Index was published over 20 years ago, Ms James said that it remained the gold standard to analyse jobs for the risk of distal upper extremity disorders[124].

55. Professor Chan, Chair Professor of the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University, graduated with a bachelor of science degree in Occupational Therapy from University of Alberta. He received a master’s degree from the University of Hull in the field of Health Administration and Research. He also has a PhD from the University of Alberta in educational psychology. He started teaching in Hong Kong Polytechnic University in 1994. He taught occupational therapy and ergonomics. He was a founding member of the Hong Kong Ergonomics Society in 2000 and rose up the ranks to become President of the Society in 2011 and 2013. He was a council member of the Occupational Safety and Health Council of Hong Kong for 6 years during which time he was Chair of the Research Committee of the Council[125]. Although he had not used the Strain Index before this case, he gave evidence that, with his experience, he would be able to work with and interpret the Strain Index[126].

56. I have no hesitation in accepting both Ms James and Professor Chan as experts whose opinion can be of assistance to me in this case.

57. The following definition appears from the Strain Index:

“The Strain Index is a semi-qualitative job analysis methodology that results in a numerical score (SI) that is believed to correlate with the risk of developing distil upper extremity disorders. The index is based on multiplicative interactions among its task variables, consistent with his urological, biomechanical, and epidemiological principles. The SI score represents the products of 6 multipliers that correspond to 6 task variables. These are (1) intensity of exertion, (2) duration of exertion, (3) exertion permitted, (4) hand/wrist posture, (5) speed of work, and (6) duration of task per day.
The 1st 5 task variables were identified from the scientific principles. The 6th was included because the authors believe it is a relevant factor.[127]”

58. Appendix A to the Stain Index contains a “User’s Guide for the Stain Index” which is set out in the appendix to this judgment. It was not disputed that, according to Step 5 of the User’s Guide for the Stain Index:

“Preliminary testing has revealed that jobs associated with distal upper extremity disorders had SI Scores greater than 5. SI Scores less than or equal to 3 are probably safe. SI Scores greater than or equal to 7 are probably hazardous.”[128]

59. There was very little agreement between the experts andsubstantial disagreement. The only areas of agreement were:

“Estimation of risks associated with the work/the Strain Index (SI)
4. Ms T James and Prof. C Chan agreed that the Threshold Limit Value (“TLV”) for Hand Activity method would demand more subjective judgment by the assessor compared to the Strain Index (SI). Both are commonly used to evaluate risk factors for work-related upper limb musculoskeletal disorders.
Occupational safety and health practices
5. Prof. C Chan and Ms T James agreed that the results generated from the SI and the TLV for Hand Activity indicated the need for the Department of Health to implement actions to lower the potential risks associated with the work processes and tasks. The responsibility would rest with the employer to take action to lower the occupational risks associated with surgical and non-surgical tooth extraction procedures.”[129]

60. The following table shows the difference between the 2 experts in their assessment, based on the Strain Index, of the risks posed by SX in present case:

Expert on
SX
Intensity of
Exertion
Duration of
Exertion
Efforts
per
Minute
Hand-
Wrist
Posture
Speed of
Work
Duration
per Day
Strain
Index
CC[130]
6
0.5
3
1
1
0.5
4.5[131]
TJ[132]
6
2
3
2
1
0.75
54[133]

61. The major difference between the 2 experts arises from their different assessment of the value to be assigned for the task variable called “Duration of Exertion”. The difference between the experts on the task variable “Hand-Wrist Posture” and ‘Duration per Day” was less marked. Both experts assigned a value of 6 to the task variable “Intensity of Exertion”, which is the most critical variable with increasing levels of intensity of exertion implying increasing levels of strain on the distal upper extremity[134]. Both experts also assigned a value of 3 to the task variable “Efforts per Minute” and a value of 1 to the task variable “Speed of Work”.

62. The experts’ differences also stem from 5 areas of disagreement, which are set out in the “Joint Note on Areas of Disagreement of the Parties’ Ergonomic Experts”[135]. These areas of disagreement are:

1) Disagreement 1:  Whether the SI method, as originally designed, is suitable for use as a tool to assess the risks associated with the plaintiff’s work as a dental officer in NDH
2) Disagreement 2:  Whether the methodology adopted by Ms. James is valid and reliable
3) Disagreement 3:  Whether the methodology adopted by Professor Chan is valid and reliable
4) Disagreement 4: What is the workload basis upon which the SI scores are calculated
5) Disagreement 5:  Whether assessment by the Threshold Limit Value for Hand Activity methodology is useful in assessing the occupational risks of the plaintiff

[size=1em]Disagreement 1: Whether the SI method, as originally designed, is suitable for use as a tool to assess the risks associated with the plaintiff’s work as a dental officer in NDH

63. It is expressly stated in the Strain Index:

“To date, the Strain Index methodology has been applied to 25 relatively simple jobs from a single plant associated with a single type of industry (pork processing).These jobs were characterized by stereotyped exertions performed, on average, 14 times per minute … .
…
At this time there is no proposed method for multiple task analysis. Currently, each task of a multitask job can be analyzed separately by considering duration of task per day. If the distal upper extremity is somewhat analogous to the low-back, it is suspected that the hazard potential of the job is primarily mediated by peak stresses, not time-weighted or some other averaged value. As a result, an elevated Strain Index score for one task of a multitask job, with consideration of duration of task per day, might predict increased risk. Development of a multitask analysis methodology will require opportunities to evaluate such jobs and compare the results to the observed morbidity. It is a challenge for the future.
…
Future studies should include multiple task analysis and evaluation of predictive validity for other outcomes (e.g., severity rate, turnover, etc.).”[136] [Emphasis added]

64. The following publications also show that the SI methodology has been used for homogeneous jobs, and not heterogeneous jobs:

(a)  “Predicting Work-Related Incidence of Lateral and Medical Epicondylitis Using the Strain Index” (Z. Joyce Fan et al, 2014):
“The original SI was developed for a mono-task job, with only one type of forceful exertion.  In practice, there are usually multiple tasks involved and researchers, therefore, have tried different ways to generate one force value for jobs with several forceful exertions. In the present study, the most common forceful exertion approach is used. Repetitive muscle activity included not only forceful hand exertions but also all other hand muscle activities, even those with very low force exertions [Bao et al.,2009]. The methods using the most common-muscle forceful exertion and repetitive muscle activity (the “common-muscle” approach) tend to produce higher SI scores [Bao et al.,2009].  …”[137]  [Emphasis added]
(b)  “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), under “Future Research” and “Estimating Stresses: Complex Jobs”:
“There are many jobs in industry in which the weight of the object or the applied hand force, the duration of the applied force, and/or the hand-wrist posture frequently change during a job cycle. Traditional approaches to account for variation in physical exposure within a job cycle are (a) simple averaging of each job’s exposure variables, (b) use of the most common (typical) value of exposure variable to represent all exposure levels, (c) use of peak values of exposure variables to represent all exposure levels, and (d) time-weighted or frequency-weighted averaging of either exposure variables or exposure dose.
It is clear from the literature that these approaches often underestimate or overestimate the physical exposure to the worker (Dempsey, 1999, Garg & Kapellusch, 2009b). Herrin, JAraiedi, and Anderson (1986) concluded that averaging or pooling of stressful and non-stressful tasks tended to obscure the differences between tasks that contributed most to overexertion injuries and those tasks that did not contribute to overexertion injuries. Techniques such as time of frequency weighting, using only peak exposure, and determining cumulative exposure have been suggested to overcome problems associated with simple averaging. Unfortunately, each of these techniques has weaknesses.
Time-weighted and frequency-weighted approaches assume that an increase in time of frequency is equivalent to the same increase in force. Garg & Kapellusch (2009b) show that this assumption may result in exposure miscalculation the peak force approach assumes that all exertions are at the peak force level and pass tends to overestimate stresses, particularly in jobs with long cycles and infrequent use of high force. Cumulative exposure accounts for all exertions performed by a worker, but it is not clear whether upper limb [musculoskeletal disorders] are caused by cumulative exposure of peak exposure (Dempsey 1999). Thus, the implied assumption is that an increase in force magnitude has the same effect on injury potential as an equivalent increase in duration of force caused by an increase in either repetition or duration of force exertion.
Although both peak and cumulative loads have been shown to be related to [musculoskeletal disorders], there are some major concerns with these approaches (Garg and Kapellushch, 2009a, 2009b). Thus, there is a need to develop job analysis methods that account for significant variations in important job physical risk factors, such as force, posture, and duration per exertion in a job cycle. Garg and Kapellushch (2009b) have proposed use of index computation methods that divide a job into subtasks. A baseline strain score is assigned from the most stressful task, and then some form of incremental increase in strain is added to the baseline from the remaining subtasks. Although the general technique has shown some promise, it is not at all clear what this incremental increase in strain should be from performing other subtasks.”[138] [Emphasis added]

On the other hand, other studies on single task manufacturing processes have provided additional evidence of the Strain Index’s external validity and predictive validity: “Predictive Validity of the Strain Index in Manufacturing Facilities” (Rucker & Moore, 2002)[139] and “Predictive Validity of the Strain Index in Turkey Processing” (Knox & Moore, 2001)[140].

65. It is the defendant’s case that[141]:

“20. …
(a) The Strain Index methodology, as originally designed by Moore & Garg, is for single-task jobs and is unsuitable for complex jobs such as surgical and non-surgical extractions carried out by a dentist;
(b) In order for assessments to be carried out for a complex job, modifications of the originally designed methodology has to be made;
(c) There are numerous attempts to modify the originally designed methodology to make it suitable for assessment of complex jobs;
(d) Some approaches result in overestimation or underestimation of the risk faced by a worker; and
(e) One suggested approach is to divide a job into sub-tasks.
21. The SI methodology has never been employed to a job as complex as that of a dentist. Ms. James’ insistence in following the original method without modification must be rejected … The Court will have to decide whether, after modifications as suggested by Prof Chan (Ms. James advocates for strict adherence to the original design, which must be flawed in view of the numerous research publications), the methodology is a useful one for assessing the risk faced by P at the material time. If the answer is in the negative, the methodology would have to be rejected altogether, and all results therefrom ignored.”

66. The plaintiff’s case is that SX can be considered as a monotask because:

(a)  the procedure has the same operator throughout;
(b)  the operator cannot stop and must complete the task;
(c)  the task is conducted at the same location;
(d)  Professor Chan agreed in his evidence with the above 3 points[142];
(e)  the product is identifiable (an extracted tooth);
(f)  there are monotask attributes of similar repetitive, frequent, forceful gripping of tools; and
(g)  the EF identifies SX as a Unit of Work[143].

The plaintiff also relied on the extract from “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), under Example 1: Flywheel Subassembly[144] to demonstrate the correct application of the Strain Index to a task which involved a number of different movements of both hands:

“Example 1: Flywheel Subassembly
Flywheel subassembly is a very-high-repetition and moderate-force job. This job consists of picking up a flywheel weighing 3.8 kg from a pallet with both hands, placing it into a fixture, placing a magnet on the flywheel, placing screws in the magnet, and tightening screws using a suspended, inline, power screwdriver. After completion, the flywheel is removed from the fixture and stacked on a separate pallet. Cycle time is 15s; two cycles were analyzed.
Strain Index analysis: Example 1. Force requirements for the job vary from 1 to 5 on the Borg CR-10 scale (Figure 4.5), corresponding to Strain Index ratings (SI ratings) of 1 to 3. The Strain Index methodology calls for an overall rating of force that best represents the requirements of the job; thus the force rating is not necessarily a pure measure of peak or average force. In this example, a majority of time is spent at a force level with an SI rating <2; however, nearly half of efforts during the cycle occur at an SI rating of 3. These higher force requirements correspond to when the worker is using a multipoint pinch to lift the flywheel. The worker cannot grasp the flywheel in a balanced fashion. This task creates a torque on the hand and leads to greater pinch forces than would normally be required to manipulate a 3.8-kg object. These higher forces occur every cycle and represent a material portion of the cycle time; therefore, the Strain Index intensity of exertion for this example is hard, an SI rating of 3.
Each time a worker grasps an object, regrasps an object, or substantially increases the force required while grasping an object, an exertion has occurred. By counting the peaks in the force plot of Figure 4.5, one will find that the worker exerts force 17 times in 30 s. Thus, the Strain Index number of exertions per minute is 17 per 30 s, or 34 efforts per minute, corresponding to an SI rating of 5.
Duration of exertion is determined by comparing the time one spends exerting effort with the total observation time. In this example, the worker is exerting effort for approximately 24 out of 30 s. This amount of time equates to 79% duration of exertion and received an SI rating of 4.
Posture rating is determined on the basis of the most representative posture used during the job. For this example, posture ranges from SI ratings of 1 (very good) to 4 (bad) during the cycle. A majority of time is spent with postures that are very good or good. The occasional bad postures occur with generally lower force requirements. Thus, the representative Strain Index posture rating for the job is fair, corresponding to an SI rating of 3.
Speed of work is used to account for very fast motions that interfere with recovery time during a cycle. In this example, it is clear that the worker is exerting effort during most of the cycle and has essentially no opportunity for meaningful rest. Furthermore, during observation, the worker appeared to be “rushing” the work. Thus, speed of work is fast, corresponding to an SI rating of 4.
This job is performed for 8 hr per day, corresponding to an SI rating of 4. A summary of all SI ratings and their corresponding multipliers is provided in Table 4.9. The SI score for this job is 81, indicating that workers performing this job are at high risk for injury.”

Table 4.9. Strain Index (SI) Ratings, Multipliers, and Overall Score for Example 1

______________________________________________________________________________________________________

Intensity
of Exertion Number of
Exertions
per Minute
Duration
of Exertion
Hand-Wrist
Posture
Speed
of Work

Hours/Day
_____________________________________________________________________________________________________
Measurement Hard 34 79% Fair Fast   8
Rating   3   5   4   3   4   4
Multiplier   6.0   3.0   2.0   1.5   1.5   1.0
_____________________________________________________________________________________________________
Note: SI score = 6.0 x 3.0 x 2.0 x 1.5 x 1.5 x 1.0 = 81.0 (hazardous).”

67. In the “Joint Note on Areas of Disagreement of the Parties’ Ergonomic Experts”[145], Ms James stated that SI methodology was not designed for multi task jobs. For this reason, the task of SX and the task of non-surgical extraction were considered separately rather than together for the analysis. Further modification, such as the approach used by Professor Chan, to the methodology would render it invalid. In the same Joint Note, Professor Chan stated that the SI method is useful for describing the potential effects of the risks associated with the job on a cohort of workers, but not the risks on a worker who performs the job. Furthermore, the Strain Index method was designed for homogenous work rather than heterogeneous work involving many work steps and procedures, such as that of a dentist. It was, therefore, unsuitable for assessing the plaintiff’s occupational risks without modifications.

68. In evidence in chief[146], Ms James stated that Professor Chan seemed to have used parts of the Strain Index methodology, but other parts were from elsewhere, without any literature in support. She agreed with the statement that the Strain Index methodology is useful for the potential risks associated with the job on a cohort of workers but not the risks on a single worker who performs the job, and she explained that she looked at it as a cohort of workers doing the same sort of task for the same amount of time, in the same manner, and that is why she looked at videotapes of other dentists. She also stated that the Strain Index methodology accommodated, to some degree, the heterogeneous nature of the task of SX because, even though the tasks were slightly varied, the dentist was still holding instruments, manipulating them within a patient’s oral cavity: it was all similar work and was not different enough that it would warrant not using the Strain Index methodology. She disagreed with Professor Chan that one should divide the task of SX into subtasks. When one does so, one begins to minimise the amount of time spent in each sub task. When you look at them separately, there is no good way to bring them back together as a whole. It was not possible, using our current methods that are validated, to analyse each and every subtask and then summate them to produce a SI score. Later on in her evidence she explained this further in these terms:

“So if you take a task and you break it into each individual sub task, then the amount of time the duration of exertion is occurring is minimised for each subtask. So when you would apply the multiplier to it, it would be a much lower number than when you are looking at the task as a whole”[147]

Ms James said that she followed the statements in the Strain Index that “[at] this time there is no proposed method for multiple task analysis. Currently, each task of a multitask job can be analysed separately by considering duration of task per day”, to separately analyse the multi task in the present case, being surgical extraction and regular extraction, as the Strain Index method did not tolerate mixing of tasks because the mathematics behind it had not taken that into consideration. Her SI score for non-surgical extraction was 13.5 and for SX was 54. To mix a task with a high SI value with a task with a low SI value would reduce the overall risk and mask the risks that arise from the task with the high SI value. Nothing in the Strain Index allows one to mix 2 different tasks together and come up with a risk per day formula. Ms James did not agree with the approach of Professor Chan to average the percentage maximum voluntary contraction (“MVC”)[148] because when one averages the highest and the lowest it puts everything at a sort of medium-range which is contrary to the statement in the Strain Index that “[if] the distal upper extremity is somewhat analogous to the low-back, it is suspected that the hazard potential of the job is primarily mediated by peaks stresses, not time-weighted or some other averaged value”.

69. Under cross examination, Ms James would not agree, and would not say, that the variation is that great, between different parts of the task of SX, when the dentist is manipulating the dental tool within the oral cavity. Sometimes the dentist used greater force than other times, but the motions and the activities were very, very similar[149]. Ms James explained that there was some confusion between jobs and tasks but that the Strain Index was primarily focusing on a task; for example, there could be different types of tasks for a machine operator[150]. Although the work of dentists is quite complex, in that the dentists were gripping tools and manipulating them in a person’s mouth, the work required quite stereotypical motions and exertions[151]. She agreed that dental work involved multiple tasks and that is why she separated SX and nonsurgical extractions as being 2 different types of tasks: to break down SX into multiple tasks would produce the smallest multiplier which was not what the Strain Index intended. She did not agree that SX ought to be treated as a multitask by itself which may be broken down into subtasks. The task is the work product, the subtask is not the work product: what one analyses is the work product or the work process: in this case, the surgical extraction. The work process is not cutting the gum or drilling the tooth, the work product or process is the whole task which is SX[152]. Professor Chan had no precedent to rely on to modify the test set out in the Strain Index. By straying from the methodology, he could not apply the results produced by the Strain Index[153]. She had not previously applied the Strain Index to dental work but had applied it to the work of a gastroenterologist performing colonoscopies[154].

70. In his evidence in chief, Professor Chan stated that according to what he saw in all the papers on the Strain Index, homogeneity of the task refers to very, very, homogenous work, and the repetitiveness is very high, such as a work cycle of 30 seconds. Everyone was doing that for the whole day: we are talking about maybe thousands of repetitions which is notapplicable to the SX performed by the plaintiff[155]. In cross examination, Professor Chan was referred to the extract from “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), under Example 1: Flywheel Subassembly[156] and asked the following questions:

“DR JONES: Professor Chan, in order for Professor Garg to apply his methodology to this task, it is actually quite a complex task, flywheel subassembly, would you agree, from its description?
A. Could you repeat that again?
Q. The flywheel subassembly is quite a complex task.
A. No, I don’t think so. It all depends on which task that you compare with.
COURT: No, the task as described in that first paragraph on page 172[157].
A. So no.
DR JONES: You say that's not a complex task?
A. No, it is not.
Q. And that’s not a monotask, is that right?
A. That's a monotask.
Q. It is a monotask?
A. Yes.
Q. It is quite complex but it is a monotask?
A. I did not say it is complex. I said it is not complex.
Q. So for that sort of task, with that sort of varying forces --
COURT: Before you continue, why do you say it is a monotask when there are so many elements to it, lifting the flywheel, placing a magnet on it, placing screws, tightening screws, and then removing it and stacking it? Aren't these different tasks, not a monotask?
A. Yes, it is different -- I can further divide them into subtasks. For sure I can. But if compared with other tasks that I have in mind, in terms of complex, this is relatively simple. So if I need to give a "yes" or "no", then I would tend to say no. Because the task could be --
COURT: You would tend to say it is not complex.
A. That’s right.
COURT: Is it semantics? That it is a monotask which you can divide into subtasks, or you can say it is multiple tasks?
A. My Lord, even the simplest task, you still can divide them into the subtask. Unless there is no change in the posture. So that's one. The second, very important criteria, is it depends on the speed, the time that allows for this task, for example for this the entire task is 15 seconds, as what it talked about here. So what it means is the upper limb is so busy doing different things, so when you look at movement, for example, it is very, very busy across the 15 seconds. So I think it depends on which perspective that you look at it, but the task, my Lord, if the task is 2 seconds -- sorry, 20 seconds – sorry, 2 minutes, then I would regard that as not monotask because the time is very long, that -- the movement very slow, then different muscles would involve in different movements. But for this particular one –
COURT: I understand. You say if it is 2 minutes then it is not monotask. Please carry on, Dr Jones.
DR JONES: Professor Chan, what about the hand movements dentistry, in surgical extraction? Wouldn't they be sort of equivalent to a monotask?
A. Say it again?
Q. The hand movements, like in this flywheel assembly, [the] multiple [hand movements], and for a longer time, of course, but wouldn't that be a monotask?
A. No, I disagree. I think it is very, very difficult to compare a work cycle which is 15 seconds, to a work cycle is much, much longer.
Q. What, 40 minutes, perhaps? Is that what you mean? 40 minutes versus 15 seconds?
A. I would not say cycle time is 40 minutes.
Q. 20 minutes? Not sure?
A. No, it doesn't really matter. Because the scale is just too big a difference. We are talking about 15 seconds, and then in others we are talking about in tens of minutes.
Q. We are talking about 15 seconds for 8 hours, with the flywheel assembly.
A. Yes, so the cycle, as what you can count, would repeat for, I don't know how many times, thousands of times a day.
Q. I would put to you, Professor Chan, that the dentist's hands cycle thousands of times a day when they are doing SX, and X, in the mouth.
A. I’m not sure.[158]”

71. In the Strain Index methodology, the terms “cycle” and “cycle time” referred to the exertional cycle and average exertional cycle time, respectively. The duration of recovery per cycle is equal to the exertional cycle time minus the duration of exertion per cycle[159]. I am not persuaded that the Strain Index can only be applied to monotask jobs with a short cycle time measured in seconds and not minutes or tens of minutes. Certainly no literature has been cited to me containing such a limitation on monotask jobs. On the contrary, the articles relied upon by the defendant included “Predictive Validity of the Strain Index in Manufacturing Facilities” (Rucker & Moore, 2002)[160] in which the authors collected exposure data for 10 jobs at a hose connector manufacturing plant and for 18 jobs at a chair manufacturing plant. The work involved included furniture assembly work, foam trimming work, wheel assembly work, and the work of a press operator[161]. All these jobs were described as single task jobs[162]. Although there was no discussion of the length of the cycle time of these various jobs, the description of these jobs suggests to me that the cycle time was not limited to a short cycle time measured in seconds, and not minutes or tens of minutes. Further support for my conclusion that the Strain Index can be applied to monotask jobs with long cycle times can be found from the following extract from Reviews of Human Factors and Ergonomics, Garg and Kapellusch, 2011:

“To determine number of exertions, duration of exertion, and hand-wrist postures, most researchers rely on videotaping the job, then analyzing the videotape in slow motion to determine frequency of exertion, duration of exertion, and hand-wrist posture. This is a very time-consuming and tedious process especially for those jobs that have long cycle times (more than a few seconds).[163]” [Emphasis added]

72. I prefer the evidence of Ms James that the Strain Index methodology accommodated, to some degree, the heterogeneous nature of the task of SX because, even though the tasks were slightly varied, the dentist was still holding instruments, manipulating them within a patient’s oral cavity: it was all similar work and was not different enough that it would warrant not using the Strain Index methodology. Her opinion is supported by the extract from “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), under Example 1: Flywheel Subassembly[164] and by the article, “Predictive Validity of the Strain Index in Manufacturing Facilities” (Rucker & Moore, 2002)[165], which I have just referred to.

73. I also accept the opinion of Ms James in preference to the opinion of Professor Chow that one should not divide the task of SX into subtasks. As Professor Chan himself accepted, there is no literature to support his approach[166]. I prefer the opinion of Ms James that one should not divide the task of SX into subtasks because, to do so would minimise the duration of exertion for each subtask, which would attract a much lower multiplier than if one were to assess the duration of exertion of the task as a whole. The opinion of Ms James in this regard is supported by the extract, that was relied upon by the defendant, from “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), under “Future Research” and “Estimating Stresses: Complex Jobs”:

“Garg and Kapellushch (2009b) have proposed use of index computation methods that divide a job into subtasks. A baseline strain score is assigned from the most stressful task, and then some form of incremental increase in strain is added to the baseline from the remaining subtasks. Although the general technique has shown some promise, it is not at all clear what this incremental increase in strain should be from performing other subtasks.”[167] [Emphasis added]

Whilst modifications to the strain index have been suggested to cater for multi tasks, unless and until such modifications are scientifically validated, including Professor Chan’s modifications, I am not prepared to accept his opinion and assessments based on his modifications. As Ms James said in her evidence, Professor Chan’s modifications are untested in practice, unsupported by the literature and unvalidated by peers[168].

[size=1em]Disagreements 2 to 5

74. The remaining areas of disagreement are:

“Disagreement 2: Whether the methodology adopted by Ms. James is valid and reliable
Disagreement 3: Whether the methodology adopted by Professor Chan is valid and reliable
Disagreement 4: What is the workload basis upon which the SI scores are calculated
Disagreement 5: Whether assessment by the Threshold Limit Value for Hand Activity (“TLV”) methodology is useful in assessing the occupational risks of the plaintiff”

75. As I do not accept the opinion of Professor Chan that the Strain Index is unsuitable for assessing the plaintiff’s occupational risks without modifications, I need not consider Disagreement 3, namely, whether the methodology adopted by Professor Chan is valid and reliable.

76. I turn to consider Disagreement 2, namely, whether the methodology adopted by Ms James is valid and reliable. In the “Joint Note on Areas of Disagreement of the Parties’ Ergonomic Experts”[169], the disagreement between the parties is expressed as follows:

“Disagreement 2:
Whether the methodology adopted by TJ[170] is valid and reliable.
TJ: The methodology used by TJ is described in TJ5. It is valid and reliable, for the following reasons:
(1) Step 1: TJ observed an actual dentist in Raleigh, North Carolina to better acquaint herself with the specific tasks and tools that would have been used by Dr. Yeung. It is very common practice by ergonomic practitioners to get acquainted with the work before assessing the actual work or going to the worksite. No videos were observed during this time from the internet, the Raleigh dentist, or otherwise. This step has no impact on the validity of the analysis as no data were collected during this observation.
(2) Step 2: Dr. Yeung was asked to answer questions about her work using a photo-based tool. Further questions were asked during a Skype interview. Again, this is common practice by ergonomic practitioners to interview and gather information before conducting an assessment. There was no need for the photo-based tool to be validated as it was only used as a guide to help determine the three task variables that are qualitative in nature and rely on the ergonomist’s subjective judgment. These variables (intensity of exertion, posture, and speed of exertion) could have been determined without the photo-based tool but its use provided better quality information to make those determinations.
(3) Step 3: The primary purpose of asking Dr. Yeung to identify videos that could be used to analyzed the tasks of interest was to ensure the same procedures, using similar techniques and equipment were analyzed. Dr. Yeung alerted TJ to any differences in technique and equipment in the videos compared to Dr Yeung’s actual work. However, since SI assesses work for groups, not individuals, the videos do not need to exactly reflect the work performed by Dr. Yeung. It also does not matter how long the video lasts or which videos are analyzed, provided the video is representative of the task (which these were.)
(4) Step 4: The level of strenuousness (or intensity of exertion) was determined through interview with Dr. Yeung with guidance from the photo-based tool. “Intensity of Exertion” is independent of “Duration of Exertion” and “Efforts per Minute.” TJ is an experienced ergonomist as required by Moore and Garg’s method, who timed and counted, efforts of dentists performing SX and X, while CC[171] did not. There is nothing misleading.
(5) Step 5: The variables of “duration of task per day” were calculated using Dr. Yeung’s job records and through interviews with her.
(6) Step 6: Moore and Garg’s methodology for determining the SI score was followed exactly. Moore and Garg do not require sub-dividing tasks into sub-tasks. In fact, if SX was divided into individual sub-tasks, the resulting duration per day for each would be < 1 hour. The net effect of this approach serves to minimize the overall risk because the resulting SI score for each sub-task is reduced by .25 (the duration per day multiplier for < 1 hour.) This incorrect approach was taken by CC which is why the risk for all subtasks in his calculations is so low. This approach was not the intent of the Moore and Garg methodology. Otherwise all tasks (for all jobs) would have minimal risk.
CC: The methodology adopted by TJ, as detailed in the “step by step explanation” provided by TJ in TJ5, is not valid or reliable, for the following reasons:
(a) Step 1: TJ observed videos of a female dentist at work in Raleigh, North Carolina to identify and familiarize herself with the actions and tools used.
TJ admits that the videos were from the internet. The choice of these videos appears to be based on TJ’s own judgment and the Plaintiff did not seem to have viewed these videos prior to assessment. Whether these video actually represent the actions and tools adopted or used by the Plaintiff at the material time is unknown.
(b) Step 2: The Plaintiff was asked to self-assess by way of a photo-based tool. TJ then conducted Skype interview with her to better understand “the physical requirements, postures, and tools used during extractions”.
TJ did not provide evidence on the validation of the photo-based tool, and the psychometric property of the tools such as validity and reliability.
(c) Through Step 1 and 2, TJ assessed the variables of “intensity of exertion”, “wrist posture” and “speed of work” for the purpose of calculation of SI Index.
Such process would have involved predominately subjectivity of both TJ and the Plaintiff. The validity of findings based on the memory recall of the Plaintiff (i.e., from her self-reporting or assessment) would have serious issues on validity.
(d) Step 3: The Plaintiff was asked to find videos online of other dentists performing extractions with the same tools and using the same technique as the Plaintiff. It is apparent that TJ did not verify the types and models of the equipment that appeared in the videos, against those used by the Plaintiff at the material time. There is no statement made by TJ about verifying the comparability of the procedure, posture and speed of work between those observed in the videos and the actual work performed by the Plaintiff.
(e) Step 4: The videos were observed and used for the calculation of the variables of “duration of exertion” and “efforts per minute” in the calculation of SI Index. TJ did not define the level of strenuousness to be regarded as “exertion”. The “duration of exertion” and “efforts per minute” derived would therefore be misleading.
(f) Step 5: The variables of “duration of task per day” was calculated using the Plaintiff’s job records and through interviews with the Plaintiff.
Please see Disagreement 4 below.
(g) Step 6: The SI score was calculated from the six variables assessed in the manner described above. TJ did not sub-divide the extraction procedure into specific steps which would have involved exertion. Please see Disagreement 3 below.”

77. Ms James detailed her assessment and computations in her 1st expert report[172] to which she attached her worksheet[173] which is reproduced below:

Strain Index Worksheet – Yeung Lai Ping

Surgical Extractions (SX)

A) Intensity of Exertion

Intensity Light
(<10%) Somewhat Hard
(10-29%) Hard
(30-49%) Very Hard
(50-79%) Near Maximal
(>80%)
_________________________________________________________________________________________
(Barely noticeable or relaxed effort (Noticeable or definite effort) (Obvious effort) (Substantial effort) (Uses shoulder or trunk for force)
Multiplier
1
3
6
9
13

B) Duration of Exertion

Total Duration of Exertions X 100 = 9.17 X 100 = 75.3%
Total Observation Time 12.17

Duration of Exertions <10% 10-29% 30-49% 50-79% >80%
____________________________________________________________________________________
Multiplier .5 1 1.5 2 3

C) Efforts Per Minute

Total Duration of Exertions = 244 = 20.05
Total Observation Time 12.17

Efforts per Minute < 4 4-8 9-14 15-19 >20
__________________________________________________________________________________________________
Multiplier .5 1 1.5 2 3

D) Hand/Wrist Posture

Extension 0-10˚ 11-25˚ 26-40˚ 41-55˚ >60˚
Flexion 0-5˚ 6-15˚ 16-30˚ 31-50˚ >50˚
Ulnar Deviation 0-10˚ 11-15˚ 16-20˚ 21-25˚ >25˚

Rating Very Good Good Fair Bad Very Bad
_________________________________________________________________________________________________
(Perfectly neutral) (Near neutral) (Non-neutral) (Marked deviation) (Near extreme)
Multiplier
1
1
1.5
2
3

E) Speed of Work

Rating Very Slow (<80%) Slow (81-90%) Fair (91-100%) Fast (101-115%) Very Fast (>115%)
__________________________________________________________________________________________
(Extremely relaxed pace) (Taking one’s own time) (Normal speed of motion) (Rushed, but able to keep up) Rushed and barely/unable to keep up)
Multiplier
1
1
1
1.5
2

F) Duration Per Day

Duration per Day < 1 hour 1 – 2 hours 2 – 4 hours 4 – 8 hours 8 hours
_________________________________________________________________________________________________
Multiplier .25 .5 .75 1 1.5

SI Score = Intensity of Exertion Duration of Exertion Efforts per Minute Posture Work Speed Duration
per Day

6
x
2
x
3
x
2
x
1
x
.75
= 54

_________

_________

_________

_________

_________

_________

______

78. It was not disputed that some of the variables were measured whilst others were estimated. Intensity of Exertion was estimated, Duration of Exertion was measured, Efforts per Minute was measured, Hand/Wrist Posture was estimated, Speed of Work was estimated, and Duration of Task per Day was measured[174].

79. The plaintiff’s case was that:

“82. This orthodox method was applied by TJ and explained in her reports to deal with D’s departures from the SI, and with TJ4 providing a dissected worked example of the SI method. P’s Opening Bundle contains Notes on the Strain Index (Tab 4) and a Note on the Ergonomic Evidence (Tab 5), which were intended to demonstrate the practical application and purpose of the SI in layman terms and describe the correct method of application. These Notes continue to be relied upon.
83. The SI is a complex assessment of 6 variables that are specifically interrelated and computed in a manner described in detail by M&G (P255-270). The experienced ergonomist is guided through the assessment process by Appendix A which contains ‘A User’s Guide for the Strain Index’ with a series of Steps, to produce a Worksheet and Calculate the SI Score (P269-270).
84. TJ strictly complied with the M&G method, detailing her assessment steps, worksheet and computations in her first expert report (TJ1 at C134) from which she did not deviate during the following 3 years. This is in sharp contrast to CC who departed from the SI and altered his assumptions, figures, reasoning and conclusions as he attempted to ‘construct’ and rationalise his illogical and inconsistent theory and methodology. A few further points on the orthodox M&G SI are summarized herein.
85. The only SI variable that D can influence is the Duration of task per Day, i.e. the number of SX tasks (measured in hours) allocated to P, by D, per day. This complements the duty of care resting on an employer of dentists to monitor and control P’s workload.
86. TJ took the task of interest to be a complete SX task acknowledging some variability and periods of rest within the task. TJ reasoned that most of the SX task involved hand manipulation using forces of variable intensity within the oral cavity, but an SX must be completed by a single operator and the product of the SX task is tooth extraction.
87. Initially the Duration of SX per Day was estimated by P to be 3.75 hours (C136). TJ was asked to compute the SI for the SX task if the duration of each SX was calibrated to 40 minutes (C241), in accord with the Efficiency Index (EI) for an uncomplicated molar bony impaction (E7). This was a minimum estimated duration for an uncomplicated SX task, notwithstanding it was P’s evidence (1T81/12) and that of Dr Lau (3T24 and 3T34-5) that at least 90% of the cases referred to NDH were complicated SX (4.5 0r 5 units requiring about 45-50 minutes for completion).
88. Using either P’s estimate or the Efficiency Index SX duration, TJ found the SI for SX to be 54 because the multiplier (0.75) for Duration of task/Day (in hours) remained within the 2-4 hour bracket and was therefore unchanged.[175]”

80. The defendant’s case was that:

“A.b.a. Step 1: Observing a female dentist at work in Raleigh, North Carolina to identify and familiarize herself with the actions and tools used
24. Ms. James admitted under cross-examination that the female dentist whom she observed was a Caucasian. P was not consulted about the choice of this female dentist, neither was she asked whether the tool and actions used or adopted by the female dentist were similar to that used or adopted by P. No idea is given as to whether the physical demands necessary to perform extractions were similar between the female dentist and P.
25. The exercise is at best meaningless and at worst misleading (i.e., providing inaccurate impression and information in the mind of Ms. James).
A.b.b. Step 2: Asking P to self-assess by way of a photo-based tool. Ms. James then conducted Skype interview with P to better understand “the physical requirements of the tools, postures, and tools used during extractions”
26. The photo-based tool, produced in full for the first time in the course of Ms. James’ cross-examination, may be found at [C/16/237A-AF].
27. The photo-based tool is subjective, general and vague. It generally required P to estimate, from her memory, the number of times that she adopted a certain posture or carry out certain acts within a minute.
28. Any recollection by P, who has left the dental profession for more than 12 years, must be doubtful.
29. Furthermore, as pointed out by Prof. Chan7, Ms. James has not provided any evidence on the validation of the photo-based tool, and the psychometric property of the tool such as validity and reliability.
A.b.c. Assessments based on Step 1 and Step 2
30. Through these two steps, Ms. James assessed the variables of “intensity of exertion”, “wrist posture” and “speed of work”, by way of estimation (as opposed to actual measurement).
31. Because of the deficiencies of the two steps, as expounded above, the assessments were rendered unreliable because of subjectivity of both Ms. James and P.
32. Furthermore, for “intensity of exertion”, Ms. James apparently also relies on videos from other dentists. Without the dentist involved describing to Ms. James how much force he/she is using, any estimation as to whether the exertion is hard or not is, to say the least, unreliable.
33. According to Moore & Garg [P1/21/269], one of the methods for assigning a rating for “intensity of exertion” (and it is submitted that this is the most objective assessment), is by way of assessing the percentage maximal strength8. This was not adopted by Ms. James. Instead, she said under cross-examination that she used the Borg Scale which, it is submitted, is subjective.
A.b.d Step 3: P asked to find videos online of other dentists performing extractions with the same tools and using the same technique as P
34. A total of 14 video links were purportedly provided by P to Ms. James [C/16/239]. Upon following the video links, however, it was discovered that there is in fact a total of only 11 different videos, since the 3rd, 4th and 6th videos are identical, and the 2nd and 9th videos are identical. The video links have been downloaded and copied on a CD now inserted as Tab 22 of Bundle C. It is also noted that the 5th and 10th videos are both teaching videos.
35. The Court was invited in the course of trial to view two of the videos, viz.:
(a) 1st video: Removal of a wisdom tooth – mesioangular impaction; and
[Composing one surgical extraction and one non-surgical extraction.]
(b) 5th video: Horizontal mandibular impaction and maxillary third molar.
[Composing two surgical extractions.]
36. The 5th video was the only “example” referred to in Ms. James’ reports. Please see §4(b) of TJ 5 [C/19/291].
37. The following observations are made in relation to the videos:
(a) The work environment of the extractions shown in the videos is unknown. For instance, there is no information as to the type or model of equipment (including the surgical drill) used by the dentists shown in the videos. Ms. James admitted under cross-examination that difference in work environment could affect the occupational risk faced by the dentists.
(b) There is no information as to the background of the dentists performing the dental extractions in the videos. There is no way in which it could be told whether these dentists were similar in background to P, or whether they were representative of members of the dental profession (especially Hong Kong dentists).
(c) According to Ms. James, the “surgical action period”9 measured from the 5th video was 17.77 minutes, out of which the exertion time was 14.12 minutes. This is very different from the 35 to 50 minutes claimed by P to be required for surgical extraction, with 20 to 30 minutes involving “drilling with bur on vibrating handpiece” (apparently considered by P to be the more strenuous part of the extraction procedure)10. This shows that the speed with which P worked was less than half the speed of work of the dentist in the 5th video. How could the 5th video be of any value in assessing the occupational risk faced by P?
(d) Some of the videos (e.g. the 5th and 10th videos) were obviously demonstrations, which may be somewhat different from an ordinary surgery. For instance, the operation was briefly paused at times for explanations to be given, and postures might be taken to make sure that the procedure was exposed to the camera.
(e) In at least one of the videos (the 5th video), the hammer and chissel method of extraction was used. This is very different from the methodology adopted by P at the material time, viz., by way of surgical drill.
38. By reason of the above, any attempt to use the said video links to assess the occupation risk of P must be flawed.
A.b.e Step 4: Calculation of the variable of “duration of exertion” and “efforts per minute”
39. The video links were used by Ms. James to make quantitative measurement of 2 variables – viz., “duration of exertion” and “efforts per minute”. These two variables are discussed in greater length below.
40. The first point of contention in this respect is: what amounts to an exertion?
41. Ms. James purportedly adopted the practice used by the authors of “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011) [P2/30/536], that “Each time a worker grasps an object, regrasps an object, or substantially increases the force required while grasping an object, an exertion has occurred.”
42. What Garg & Kapellusch said must however be read in the context of the particular task studied in the research concerned – viz., the manipulation of a 3.8 kg object. It cannot be the case (and is against common sense) that, however light an object manipulated in a task may be, and however effortless the manipulation of the object, an exertion has occurred every time the object is grasped or regrasped.
43. It is submitted that Prof Chan’s definition of exertion – i.e., that an exertion is measured for duration and efforts per minute only when it reaches rating 2 (i.e., somewhat hard), is reasonable, and is to be preferred.
44. Furthermore, Ms. James set out in her report the analysis in relation to the 5th video only. She did not do the same for the other video links that she said she had analysed. The Court has no way of verifying what her analysis of the videos might be, and whether they are consistent with the 5th video. It is also unknown how, in her calculations, Ms. James arrived at 75.3% for duration for exertion, and 20.05 for efforts per minute11.
45. Thirdly, even for the 5th video, the exertion time and efforts per minute are subjective and incapable of being objectively verified.
46. All in all, Ms. James’ assessment of duration of exertion and efforts per minute, based on the video links and her subjective “measurement”, must be flawed.
A.b.f Step 5: Calculation of the variable of “duration of task per day”
47. Please see Disagreement 4 below.
A.b.g Conclusion on Ms. James’ assessment
48. Ms. James’ assessment of the occupational risk of P at the material time is neither valid nor reliable, and the Court is invited to reject it.
7 Point (b) in p.5 of the Joint Note on Areas of Disagreement (Tab 6 of P’s Opening Bundle 1)
8 This is the method used by Prof. Chan.
9 §4(b)(i) at [C/19/292].
10 §21 of P’s witness statement at [B/1/5].
11 [C/10/157].” [176]

81. My conclusions on Disagreement 2 are as follows.

82. The criticism that Ms James’ observation of a Caucasian female dentist in Raleigh, North Carolina, was meaningless and misleading is completely unfounded. As she explained in her evidence, she did so primarily to understand the tools that were used and to become familiar with them: she had not collected any data during that session: she did not actually observe her perform a procedure or analyse her, she analysed the videos[177]. Likewise, the criticism of the photo-based tool[178] is unwarranted. No measurements were made during this exercise and there was no reason to require validation of the photo-based tool. Ms James relied most heavily on the videos which was just supplemented by the photo tool and the information from the plaintiff[179].

83. However, in assessing Hand/Wrist Posture, which was not as significant as Intensity of Exertion or Duration of Exertion, Ms James relied more on the photo-based tool and the Skype interview as it was difficult to see the hand posture on some of the videos she had observed[180]. The further criticism made on the photo-based tool and the Skype interview with the plaintiff was that the photo-based tool required the plaintiff to estimate, from her memory, the number of times that she adopted a certain posture and carried out certain acts within a minute and that any recollection by the plaintiff, who had left the dental profession more than 12 years ago, must be doubtful. I have already found the plaintiff to be a frank and candid witness[181]. Although I was not satisfied that her memory of some of the conversations she had had was reliable[182], I am satisfied that her recollection of the number of times she adopted a certain posture and carried out certain acts within the stated period was sufficiently reliable to be used by Ms James. During cross-examination, Ms James, an experienced ergonomist with 23 years of experience, said that the plaintiff had done this task enough, and long enough, that she felt comfortable with the information she gave to Ms James about hand posture. Ms James would ask a worker to describe for her what they did and the postures they used: if they had any doubt at all, then she would say that their account was not reliable; but the plaintiff was very sure of what she did, and the way she did it, and the methods that she used, and Ms James felt very comfortable that her account was reliable[183]. The plaintiff had performed SX hundreds of times prior to the occurrence complained of and I am satisfied that, even after 12 years, her recollection of the number of times that she adopted a certain posture and carried out certain acts within the stated period was reliable. Ms James explained in her report[184] that as hand or wrist postures progressively deviate beyond a neutral range to extremes, they are graded as “fair”, “bad”, and “very bad” and that the multiplier is selected accordingly. She prepared a table in her report showing the approximate percentage of a working day that was employed adopting a particular wrist posture, based on which she rated the overall risk of the hand wrist posture as bad, which attracted the corresponding multiplier of 2. Other than complaining that she was making an assessment of the heterogeneous job as a homogenous job, it was not suggested that this assessment, based on the photo-based tool and the Skype interview, was wrong or wrongly made[185]. Ms James explained that some of the postures were good and some of them were very bad and that she tried to come up with the posture that was most representative of the posture across the entire task and she came up with an overall riskof the hand wrist posture as “bad”[186]. As I have already found that the photo-based tool and the Skype interview communicated reliable information to her, I find that Ms James properly applied the methodology set out in the Strain Index to correctly assign a multiplier of 2 for Hand/Wrist Posture.

84. I turn to consider the criticisms levied at Ms James regarding her assessment of the Intensity of Exertion. In her evidence in chief, she said she assessed the Intensity of Exertion of the task of SX, from the time the patient came in until the time the patient left, to be hard and she explained that, as per the methodology in the Strain Index, the ergonomist has to look across the entire task and determine the Intensity of Exertion that best describes the entire task. In this case, she found the Intensity of Exertion to be light for some of the task, some she found to be somewhat hard, and some she found to be near maximal. According to the methodology, where there is a range of Intensity of Exertion across a task, one has to choose the one that best represents the task as a whole, which she did through observing videotapes of the task as well as interviews and discussion with the plaintiff[187].

85. The defendant complained that Ms James adopted the Borg Scale, which the defendant submitted was subjective, as compared with the other method of assigning a rating for Intensity of Exertion by assessing the percentage maximal strength, which Professor Chan did. Whilst the Borg Scale is a subjective measure of a person’s perceived exertion, I cannot understand why Ms James is being criticised for using the Borg Scale when the Strain Index expressly permits the use of the Borg Scale to assign rating criteria, as per the User’s Guide which is appended to this judgment. Ms James explained that one can either use the Borg Scale or the percentage of maximal strength, or even assign the rating criterion by using the Perceived Effort which is set out to the right of the Borg Scale in the User’s Guide. She determined the Intensity of Exertion according to the Borg Scale through observation of the task. Research has shown that a trained ergonomist’s estimation of that is better than force matching, and better then asking workers to just tell them what that force is[188]. I accept her evidence and find that she properly used the Borg Scale to correctly assign a rating criterion of the Intensity of Exertion and that she properly applied the methodology set out in the Strain Index to correctly assign a multiplier of 6 for Intensity of Exertion. I do not accept the criticism being levied that, without the dentist involved describing to Ms James how much force he or shewas using, any estimation as to whether the exertion is hard or not was unreliable.

86. Substantial criticism was made of Ms James’ reliance on videos from other dentists. It was suggested that the work environment of the SX, the type of drill used, and the background of the dentist that was shown in the videos was unknown, and that some of the videos were demonstrations to students instead of ordinary surgery. I accept the evidence of Ms James that she was actually looking at the amount of time that force was being exerted divided by the amount of time for that entire piece of video and it did not matter what type of drill was being used. The Strain Index was workplace-independent. Further, it did not matter for this analysis what the background of the dentist was. As the exercise was for a cohort of dentists, not an individual, she looked at a number of videos not just one. There may be less force from an experienced dentist, but then the timeframe is shorter; a less experienced dentist may exert more force over a longer period of time: so the overall ratio would not change. This evidence answers the complaint made by the defendant that the surgical action period measured from the 5th video was 17.77 minutes, out of which the exertion time was 14.12 minutes[189], which was very different from the 35 to 50 minutes the plaintiff required for SX with 20 to 30 minutes involving “drilling with bur on vibrating handpiece”[190].

87. The demonstrations were performed on live patients and they were actual patient extractions. For most of the videos, the dentists were talking while they were working. Ms Jamessaw very few instances where there were large pauses between what they were doing. Where there were pauses or where there were inconsistencies, she deducted that time so that it was more of a pure measure of the actual task[191].

88. Complaint was also made that there was no information on the dentists shown on the videos: whether they were similar in background to the plaintiff or whether they were representative of members of the dental profession, especially Hong Kong dentists. I discount this complaint and accept the evidence of Ms James that the way a dentist works and the way teeth are extracted does not vary that much from country to country and that the same risk could apply to any dentist of any experience of any race working in any dental environment[192].

89. The general complaint that was made about the use of videos by Ms James is unsubstantiated. On the contrary, it is well acknowledged that:

“To determine number of exertions, duration of exertion, and hand-wrist postures, most researchers rely on videotaping the job, then analysing the videotape in slow motion to determine frequency of exertion, duration of exertion, and hand-wrist posture. This is a very time-consuming and tedious process especially for those jobs that have long cycle times (more than a few seconds).[193]”

It was not possible to videotape the plaintiff performing an SX so many years after the matters complained of. Professor Chan based his assessment on a simulation rather than a video of an actual SX on a live patient. The parties could have cooperated to obtain videos of actual SX being performed on live patients by a cohort of dentists in Hong Kong, and they could have agreed a selection of such videos to be used by Ms James and Professor Chan for their respective assessments. As this was not done, the best evidence available for the assessment using the methodology of the Strain Index were the videos used by Ms James.

90. Her use of the video showing the use of hammer and chisel to carry out the extractionwas criticised for being irrelevant to the task of SX using surgical drills. However, Ms James explained that she referred to this particular video as an illustrative and working example of the methodology she applied in ascertaining Duration of Exertion and Efforts per Minute when she prepared her report TJ-5[194], which was a step-by-step explanation of the methodology she had applied in her original report TJ-1[195]. She did not use the videos showing the use of hammer and chisel when she prepared TJ-1 and when she compiled her worksheet[196] showing the duration of exertion as being 9.17 minutes, out of a total observation time of 12.17 minutes, which produced a percentage of 75.3%[197].

91. The specific complaint was made that Ms James set out in her report the analysis in relation to the 5th video only, that she did not do the same for the other videos so that the court has no way of verifying what her analysis might have been of those videos, and whether they were consistent with her analysis of the 5th video. Ms James has set out a methodology very clearly in TJ-5[198]. Professor Chan could have applied the same methodology on the other videos relied upon by Ms James to demonstrate inconsistency. He did not do so. As Ms James rightly complained, no one asked her to produce the raw data and her working notes for the other videos[199]. I am not at all impressed by this specific complaint that has been made.

92. Duration of Exertion and Efforts per Minute are measured values. Ms James was criticised for adopting the definition used by the authors of “Reviews of Human Factors and Ergonomics” (Garg & Kapellusch, 2011), that “Each time a worker grasps an object, regrasps an object, or substantially increases the force required while grasping an object, an exertion has occurred.”[200] Ms James give evidence that she saw a great deal of manipulation of the tools and movement of the tools. There was a lot of grasping and movement of the tool during the videos. Although she will not calculate every second that the tool was held, an effort was made when it was moved and that is what she was counting: every time one has to activate the muscles, an effort is made and every time there is effort, there is an exertion. Holding something for a prolonged period of time would not necessarily be cause for effort, or increase in effort. But the act of moving a tool itself, with resistance, as was the case in these videos, there would be effort required because there was resistance inside the mouth. Sometimes there was added force, sometimes it was low and sometimes it was high. Whether it was a light or heavy exertion, it was still an exertion. It is the cumulative effect of all the exertions. The Intensity of Exertion has a separate multiplier. The Duration of Exertion is a measure of what percentage of time one’s hands are actively exerting some effort, regardless of the level. Ms James disagreed with the suggestion that, from watching the video, it was actually very difficult for one to tell when an exertion had occurred, not to mention counting them. She said that she was able to see very clearly when an exertion was made take the time of that exertion, and then, when she was measuring the efforts per minute, to be able to count them. She had no problem doing that.[201] I accept and prefer the evidence of Ms James on these matters. I do not accept the definition of Professor Chan that an exertion is measured for Duration of Exertion and Efforts per Minute only when it reaches rating 2, i.e. somewhat hard[202], which is unsupported by any literature that has been produced.

93. The biggest difference in the multipliers chosen by Ms James and Professor Chan was in respect of the multiplier for Duration of Exertion. Professor Chan’s multiplier was 0.5 and Ms James’ multiplier was 2. I questioned Ms James about this:

“COURT: So, you see, the most critical difference between the two of you is the values for duration of exertion.
A. That’s right.
COURT: So you have got those values, you came up to a value of 75.3 per cent based on the input that you put in there, 9.17 and 12.17. Can you remember that?
A. It is that ratio, again, I would start the stopwatch when I saw the exertion on the screen, and stop it when I stopped seeing it, and then when the exertions started again I would start it again, stop it. I did that throughout that cycle. Then the denominator is that full-time, the full observation time, and so --
COURT: So the full observation time cannot be controversial because --
A. That’s right.
COURT: -- it is there, the video is that long.
A. It is what it is, that’s right.
COURT: And this value is actually quite consistent with the second one that you arrived at using, the --
A. That’s right. I did multiple assessments after that, as requested by counsel. And they all came up in the range, I believe it was 65 to 81 per cent in that range.
COURT: Let’s take the lowest, 65. What multiplier do you get?
A. So the multiplier would be --
COURT: Duration -- sorry, it is -- where is this?
A. It would be 2 instead of 3[203].
COURT: It would be 2 instead of 3.
A. Right.
COURT: You are still well above 7?
A. Yes.
COURT: 6 times 2 times 2[204] times 2 times 1 times 0.5. 48.”[205]

94. I accept the evidence of Ms James and I find that she properly applied the methodology set out in the Strain Index to correctly assign a multiplier of 2 for Duration of Exertion and a multiplier of 3 for Efforts per Minute.

95. There was little dispute about the task variable, Speed of Work. The multiplier of 1 applies whether one is working at an extremely relaxed pace, or taking one’s own time, or whether one is working at a normal speed of motion[206]. Ms James gave evidence that this is one of the estimated variables which she determined through watching the videos and also confirming with the plaintiff that they were representative of the speed at which she worked[207]. I accept the evidence of Ms James and I find that she properly applied the methodology set out in the Strain Index to correctly assign a multiplier of 1 for Speed of Work.

96. There was a substantial dispute over the task variable, Duration of Task per Day, the subject of Disagreement 4: “What is the workload basis upon which the SI scores are calculated”, which I turn to consider.

“Disagreement 4:
What is the workload basis upon which SI Scores are calculated.
TJ: Workload information was taken from interviews with Dr. Yeung, her actual hours worked, the volume of procedures performed, and the Efficiency Index of 40 minutes for surgical extractions.
CC: Workload figures are obtained from Appendix A of the witness statement Dr. YAU Chuen Kam dated 30 March 2012. “Duration of exertion” and “duration per day” are then assessed by taking an average of two scenarios: the lighter workload scenario and the heavier workload scenario. Please see CC4.”[208]

97. The defendant’s case is:

“56. The workload figures are relevant to the assessment of “duration of task per day” in the calculation of SI score. The workload figures contain 2 elements:

(a)  The number of extractions carried out per day; and
(b)  The time required for each extraction.
A.d.a Number of extractions per day
57. Prof Chan’s extraction figures are obtained from Appendix A of the witness statement of Dr. YAU Chuen Kam [B/11/144].  Dr. Yau explained while in the witness box how the extraction figures and number of sessions since July 1999 were obtained from the monthly returns [H/2/115-138], and how the relevant figures pre-July 1999 were obtained from a combination of the monthly returns and appointment book [J/Tab 1]. Although Appendix A was compiled not by Dr. Yau personally but by staff of the Department of Health, it is submitted that the figures are credible and ought to be adopted.
58. The figures put forward by P, on the other hand, are convoluted.  P has put forward two sets of workload figures:

(a)  Appendix I of her supplemental witness statement [B/2/60-75]; and
(b)  Appendix of her second supplemental witness statement [B/14/211-219].
59. In relation to Appendix I of P’s supplemental witness statement, D submitted to the Court on the 4th day of trial a table analysing and commenting on the figures put forward by P in Appendix I (please see Appendix attached herewith). P’s workload analysis [B/2/63] gives a distorted (and untrue) impression that P (i.e., dentist designated N15) had a very heavy workload during the period from Oct 1998 to Sept 1999 when compared with other dental officers such as P04 (Dr. HO Tin Lun) and T13 (Dr. TSANG Wai Ming).  In fact, only 3 monthly returns were retrieved for P04 during this period, and 6 monthly returns for T13.  The workload figures for Dr. Ho and Dr. Tsang therefore covered a period of only 3 months and 6 months respectively (as compared to a 12-month figure for P).  Furthermore, P’s workload figures do not take into account the number of sessions worked by the respective dentists during the period, and therefore no meaningful comparison of workload could be carried out.  The Court is invited to disregard P’s workload figures contained in Appendix 1 of her supplemental witness statement.
60. As for Appendix of P’s second supplemental witness statement, it is apparent that, in the end, P agrees that it is her workload per session that is material in the action herein, for such figures do away with leave period, other duties (e.g., attending lectures or meetings) etc.
61. It is however not easy to follow how the figures shown in [B/14/211] were arrived at, and no attempt has been made by P while giving viva voce evidence to explain them.

62. P’s average number of surgical extractions per session, as shown in [B/14/218] were:

(a)  From Oct 98 to Jun 99: 1.75;
(b)  From Oct 98 to Oct 99: 1.69;
(c)  From Sept 98 to Oct 99: 1.68.

63.  The corresponding figures, using Dr. Yau’s figures at [B/11/144] are:
(a)  From Oct 98 to Jun 99: 1.59;
(b)  From Oct 98 to Oct 99: 1.45;
(c)  From Sept 98 to Oct 99: 1.46.
64.  Unlike D, P has not provided figures for non-surgical extractions.
65.  The difference in workload figures between the parties may not be significant, as Prof Chan has done calculations using both sets of figures.  Please compare the calculations at [C/18/278] (using Dr. Yau’s figures) and [C/18/281] (using P’s figures).  Although the SI score for surgical extractions become different (2.25 using Dr. Yau’s workload figures and 4.5 using P’s workload figures), Prof Chan commented in §8 of CC4 [C/18/281-282] that:
“Based on the statistics presented in the second supplemental witness statement of Dr. Yeung Lai Ping dated 13.04.2016, the SI parameters were increased for the surgical procedure due to the fact that the duration was increased from 60 minutes … to 63 minutes … . As the new derived duration per day is longer than 60 minutes, the SI rating for the surgical procedure was subsequently increased to 2 and the SI multiplier was increased to 0.5. This yielded a SI score of 4.5 for the surgical procedure (from 2.25 in the previous report). … It is however noteworthy that the cut-off between SI ratings 1 and 2 is less than or equal to 60 minutes. It is in my opinion that the SI rating of 2 based on a duration of 63.6 minutes for the surgical procedure may not have imposed occupational risks significantly different from those of a SI rating of 1. The duration per day for Dr. Yeung (which is 82.4 minutes …) is still far from the 2-hour limit set for a higher multiplier. …”.
66.  The Court is also invited to reject P’s figures contained in her second supplemental witness statement, and accept Dr. Yau’s figures, for the reasons set out in the Witness Statement of LUI Wai Kay Wilkie [B/16/229-258].

A.d.b Time required for each extraction
67. It is P’s evidence that a surgical extraction would take 40-45 minutes, most of which involved “hands-on” actions. This is to be contrasted with the evidence of Dr. Sunny Tsui, who said that surgical extractions took about 40 minutes in total, with less than 25 minutes involving repetitive wrist movements13. Dr. Jacky Lau gave the length of time involving repetitive wrist movement at 25-30 minutes. The efficiency index gave the length of time for the entire surgical extraction procedure to be 40 minutes.
68. It is submitted that the evidence of Drs. Tsui and Lau are to be preferred over that of P. In particular, Dr. Lau is of comparable age and experience as P, and she is P’s own witness.

A.d.c Assessment of “duration of task per day”
69. The assessment of Ms. James in relation to duration of task per day, as expounded in TJ5 [C/19/292-293], is flawed, for the following reasons:

(a) Ms. James first of all conducted assessment on the basis of “[P’s computation] that she spent 3.75 hours per working day performing surgical extractions”. There is no explanation of how the 3.75 hours was arrived at, and how that figure may be derived from P’s latest figures at [B/14/211-214]. The assessment is futile.
(b) As for the workload analysis based on efficiency index, the figures on “number of sessions”, as shown in [C/19/296], do not seem to tally with that set out in P’s 2nd supplemental witness statement [B/14/211].

(c) It is apparent from the table at [C/19/296] that 40 minutes of “hands-on” time is assumed by Ms. James in the calculation of “duration of task per day”, no doubt based on the evidence of P. The evidence of Drs. Tsui and Lau in this respect should however be preferred over that of P (§67 & 68 above).
(d) In her assessment of “duration of exertion” and “efforts per minute” [C/19/291-292], however, a typical extraction was said to have a “surgical action period” of 17.77 minutes, with 14.12 minutes spent in exertion.

(e)  Ms. James’s approach is therefore not only inconsistent, but also, by extrapolating a 14.12/17.77 minutes’ procedure into a 40 minutes one, gravely inflated the figures.
(f)  Furthermore, in calculating duration of exertion, Ms James totally disregarded the recovery time in the work environment.  In Moore & Garg terminology, the duration of recovery per cycle is equal to the exertional cycle time minus the duration of exertion per cycle14.  By dividing the total duration of exertion time (i.e., 9.17 minutes) by total observation time (i.e., 12.17 minutes) to obtain duration of exertion as a percentage, Ms. James totally disregarded the recovery time in between work cycles.  Ms. James had in effect assumed that P would perform one surgical extraction every 12.17 minutes, while in reality P only performed 1.5 surgical extractions per session or 3 such extractions per day according to Dr. Yau’s workload figures.
70.  Prof Chan was asked by the Court to do calculations on the assumption that a surgical extraction took 30 minutes rather than 20 minutes (please see [C/18/285A & 285B]).  The SI score for surgical extracts becomes 4.5, while the SI score for the whole day’s work (taking both surgical and non-surgical extractions into account) remains at 4.5
71.  The Court is invited to adopt Prof Chan’s assessment of “duration of exertion”, as summarised in §31 of CC6.”
13 [C/6/102-103]
14 [P1/21/261]”[209]

98. The plaintiff’s case is:

a.  An enormous amount of painstaking effort has been expended on these data by P.  It was D that began the process of compiling and relying on comparative data in 2003 when drafting its Defence and any perceived shortcomings in the disclosure and availability of relevant data is D’s own doing. P asked for more comparative data, but D declined to provide this, so the Court can and should assume that the data D selected and provided to the Court is the most relevant and most favourable to D that was then available.  D should not now be permitted to attempt to denigrate the evidence derived from D’s own data and records or down play its significance. These complaints should be treated as having little or no weight.
b.  Whether the Court applies P’s or D’s data, according to TJ’s application of M&G’s method, if P worked more than 1 hour / day doing SX her risk of injury would be significant (i.e. SI = 36).  Using P’s SX and sessional data and a 40 minute cycle time, TJ determined the SI for SX to be 54 because P’s duration of the SX task was 2 hours per day.
c.  As expected, the SI, being a semiquantitative index using categorical variables, allows for a wide margin in the actual number of SX done, and sessions worked by P. It is to be remembered that these averaged data reflect 12 months of work for P at a constant rate of at least 1.6 SX per session, not a sudden spike in workload causing injury. Even Mr Lam conceded that he thought the difference was not significant (1T123/17 and 1T139/18).
d.  The comparators chosen by P (PO2 and TO2) (B64, B65, B218) were provided by D, and had contiguous data from October 1998 to June 1999. This data comparison period reflected the work done by P prior to and at the commencement of her wrist symptoms. D did not keep sessional data for their DOs during this period.
e.  Hence P benchmarked her comparators by her actual figures for clinical sessions, which are a reasonable reference figure or benchmark, for as D points out in DSkC#89, all dentists in Hong Kong ought to have the same working hours.
f.  It has never been alleged that the comparators did their work in less sessions and if they did more sessions, their SX/session rate would be even further below P’s. D’s reasoning is fallacious. If D did not understand how P arrived at her sessional data, there was every chance given by the Court to cross examine her on them. P was in fact hardworking and no allegations have been made that she did less sessions than any other dentist.
g.  P did not allege that her numbers of X were causative of her wrist injury. P’s numbers of X were comparable to other DO’s (B63). Also P made the point that invariably when an impacted SX is performed, the opposite molar also has to be extracted, and so there should be an X counted for almost every SX. This X was seen on the video during Trial and mentioned by P and Dr Lau (3T21/21-25 -3T22/1-4). The evidence of Dr Wilkie Lai is irrelevant as the comparative data do not concern September 1998.
h.  Time required for SX. (DSkC#67) P elected to chose the Efficiency Index (EI) time of 40 minutes (C296A) as the SX task cycle time. This is reasonable and in accord with P’s evidence and that of Dr Lau, and Dr Tsui was of the view that the clinical time for an SX was comparable to the EI (3T106/25).  That should be the end of the matter, but CC was instructed to use 20 minutes (DSkC#70); and then requested by the Court to revise this period to 30 minutes.  However because CC had applied whole-task multipliers to part-sub-task components, his SI was not sufficiently sensitive (see P’s Reply#19 above with reference to predictive validity by D at DSkC#19(c)) to substantially react to a 30% increase in cycle time, and hence his results were almost unchanged and no use as a tool for assessment of changes in risk.
i.  Duration of task per day. Again DSk#69 shows his lack of understanding of the SI. He muddles the Duration of Exertion multiplier with the Duration of Task per Day multiplier. The Duration of Exertion multiplier is derived from a ratio -  the time, provided it is representative of the task, doesn’t have to be the entire task duration or even a significant part of that duration as the timing and counting of efforts is tedious and impracticable over long periods, as explained by TJ at Trial (P535).”[210]

99. This very substantial dispute does not, however, translate into a substantial difference in the multiplier chosen for Duration of Task per Day[211]: Ms James’ multiplier was 0.75 (based on 2 to 4 hours of SX per day) and Professor Chan’s was 0.5 ((based on 1 to 2 hours of SX per day). This was brought out in the course of the questions that I had put to Ms James:

“Questions by THE COURT
COURT: Ms James, can I ask you to look at the article of the SI index. The original one. The Strain Index. It is at P/255.
A. Yes.
COURT: On the very last page there is a reference to “Step 5: Interpret the result”. And the sentence appears there:
“SI scores great than or equal to 7 are probably hazardous.”
A. That’s correct.
COURT: If we open that up, and then open also the counsel’s opening, tab 5, there is a very helpful table showing your calculation and comparing it with Professor Chan’s.
A. Yes.
COURT: So your score is 54.
A. Yes.
COURT: Would you not say that is alarming.
A. That’s quite alarming.
COURT: Did that cause you to thank, perhaps your data, your input was perhaps not right? To produce such a high score?
A. It is one of the highest scores that I have ever calculated.
COURT: Yes. So I was looking at the table on page 6. You see, as far as speed of work is concerned, you and Professor Chan are on the same page. It is a multiplier of 1.
A. Yes.
COURT: So far as intensity of exertion is concerned, you are also on the same page.
A. Yes.
COURT: Efforts per minute and hand/wrist posture, there is some variation, but it is 3:1 versus 2:2[212], so it is there or thereabouts.
A. Yes.
COURT: Now, there has been huge amount of dispute as to the number of hours that were spent on SX.
A. Yes.
COURT: From the data you collected, I think, including the 40 minutes of the Efficiency Index --
A. Yes.
COURT: -- you came up with a multiplier of 0.75.
A. That’s right.
COURT: Professor Chan is 0.5?
A. Yes.
COURT: Let’s assume some of the data you relied upon is inaccurate and really, the better value is 0.5.
A. Okay.
COURT: Your index will still be quite high.
A. Yes.
COURT: I did some quick calculation, about 34[213].
A. Yes.
COURT: It is not as alarming as 54 --
A. That’s correct.
COURT: -- but it’s still high. So really, I mean, the difference between Professor Chan’s assessment and yours is duration of exertion.”[214]

100. Consistent with my findings in §§19-20 above, I am prepared to accept that the data used by Professor Chan to assess the Duration of Task per Day as being more reliable than the data used by Ms James. I, therefore, conclude that the proper multiplier to adopt for Duration of Task per day is 0.5. This will reduce the Strain Index score, as per my findings and conclusions that I have reached above, to 36:

Intensity of Exertion
Duration of Exertion
Efforts
per
Minute
Hand-
Wrist
Posture
Speed of
Work
Duration
per Day
Strain
Index
6
2
3
2
1
0.5
36

101. I turn to deal with Disagreement 5:

“Whether assessment by the Threshold Limit Value for Hand Activity (“HAL-TLV”) methodology is useful in assessing the occupational risks of the Plaintiff.
TJ:
(1) The HAL-TLV is a method designed to evaluate monotask hand-intensive jobs lasting 4 or more hours per day.  Dr. Yeung did not perform surgical or non-surgical extractions for 4 or more hours per day so this is not the proper job evaluation tool to use.  Additionally, as stated in TJ’s previous reports, the HAL-TLV is a weak tool for assessing risk as it is more subjective than the Strain Index and typically used in industry for screening purposes only.
(2) The HAL-TLV relies on estimations of the peak force exerted during performance of the job, normalized on a scale of 0 to 10.  It is possible to estimate this for a specific type of tooth extraction by measuring the hand strength of another dentist and the force required by that dentist to perform the specific task.  Peak hand force is task-specific, so it must be measured or estimated in the same postures, using the same tools and the same speed required for that task.  More importantly, for these estimates to be valid, the measurements for the task must be taken immediately after performing the specific activity.  CC did not use this approach.  Therefore, his %MVC values, normalized peak forces, and HAL TLV calculations are unreliable and invalid.
(3) If the Strain Index is used correctly (which it was not by CC) no additional methods are needed for “triangulation.”
CC: The methodology triangulates the results obtained from the Strain Index. The results generated from the two methodologies are found to concur with each other.  Such convergence further corroborates the appropriate of the procedures involved in CC’s reports,  and illustrates the validity of the results generated from those procedures.”[215]

102. It is the plaintiff’s case that:

“144. …CC proposed the [HAL-TLV] be applied to estimate the hazard potential of SX (C172-175), albeit [HAL-TLV] should only be applied to a monotask job of at least 4 hours duration/day (7T32/19). CC averred that the 3.75 hours of SX/day alleged by P and relied upon by TJ (C136) was close enough for him to consider SX a monotask job (7T32/22-24) and allow him to “triangulate” the data (7T30/13)(whatever that means)”[216];
and that:
“35. …What CC has done is distort the data by inappropriately averaging the %MVC such that the [HAL-TLV] is reduced to match his invalid strain indices. TJ’s views are clearly set out in the Disagreements Document and are logical and referenced (Q595). CC’s view is not validated or supported by any literature: there is only his inadequate reference to an abstract from a physiotherapy congress in Singapore, that is neither on point, nor has gone to print as a full article. This meagre support is indicative of the little weight that should be given to CC’s evidence in this case.”[217]

103. It is the defendant’s case that:

“72. This methodology, despite its limitations, is useful in triangulating the results obtained from the SI Index. Such triangulation is desirable in view of the limitations of the SI score methodology itself, as expounded in §§18-21 above.
73. Prof Chan found that the results generated from the two methodologies concur with each other. Such convergence further corroborates the propriety of the procedures that Prof Chan adopted in relation to the SI method, and illustrates the validity of the results generated from such procedures.

74. For an example of the concurrent use of the SI index method and TLV HAL methods, please see a paper cited and relied upon by P: “Review of Human Factors and Ergonomics” (Garg & Kapellusch; 2011) [P2/30/511-560], at [P2/30/524-530, 532-535, 537, 540-542, & 545].”[218]

104. Disagreement 5 is easy to resolve. In the absence of scientific literature to support Professor Chan’s theory of triangulating results from the Strain Index and HAL-TLV, I have little difficulty in preferring the evidence of Ms James. She explained that the HAL-TLV assessment is supposed to be used on jobs that are monotask and take place for more than 4 hours a day, such as the work on an assembly line where workers are repeatedly doing the same thing over and over again for more than 4 hours a day. The HAL-TLV assessment requires the measurements for the task to be taken immediately after performing the specific activity, which Professor Chan did not do. Research has shown that agreement between the Strain Index and HAL-TLV is only about 54 or 57%. It was so weak that, in terms of triangulation, Ms James could not see the benefit of such an exercise. She applied the Strain Index because it was the gold standard. She did not think that another method was necessary.[219]

105. In conclusion, I find that the correct Strain Index Score that Ms James ought to have arrived at in this case is 36. Whilst not as alarming as her score of 54, nor the score of 81 in respect of thetask of flywheel subassembly[220], it is substantially above the Strain Index Score of 7. The authors of the Strain Index have stated that Strain Index Score “greater than or equal to 7 are probably hazardous.”[221] A Strain Index Score of 36 must raise serious concerns on the part of a prudent employer for the safety of his employees carrying out the tasks which was the subject matter of the assessment using the Strain Index.

106. However, I accept as entirely correct the submissions of the defendant that:

“78. … The SI score methodology was developed in 1995, and the material period during which P alleges that injury was caused was Oct 1998 to Oct 1999. It is apparent that the SI score method was by then only at its early stage of development and recognition. As stated by Moore & Garg themselves in the head note of their paper [P1/21/255]:
“… Preliminary testing suggests that the methodology accurately identifies jobs associated with distal upper extremity disorders versus jobs that are not; however, large-scale studies are needed to validate and update the proposed methodology.”
79. There is no evidence that such large-scale studies had been carried out by Oct 1998 to Oct 1999, or that the methodology had by then been validated.
80. The Director therefore cannot be blamed for not carrying out the SI score assessment on P’s working environment at the material time. Foreseeability at the material time therefore cannot be established using Ms. James assessment, even if it were to be preferred over that of Prof Chan.
81. It is also to be noted that both Ms. James and Prof Chan set out to assess the risk of injury faced by P in the work environment of NDH OMS&DU. Neither of them attempted to assess the risk faced by dentists in general.”[222]

I would add that, as I had stated in §89 above, the parties could have cooperated to obtain videos of actual SX being performed on live patients by dentists in Hong Kong, and they could have agreed a selection of such videos to be used by Ms James in Professor Chan for their respective assessments. As this was not done, the best evidence available for the assessment using the methodology of the Strain Index were the videos used by Ms James. Although this was the best available in the present case, and sufficiently reliable for me to rely upon to make my findings in this case, an assessment based on videos of actual SX being performed on live patients by a cohort of dentists in Hong Kong is likely to be more reliable.

[size=1em]Causation, foreseeability, breach of duty and remoteness

107. Be that as it may, the Strain Index Score of 36 is evidence to support my further findings on causation that I make as follows.

108. I have already found that the plaintiff performed 3 SX on the morning of 30 October 1999; that, in the course of those extractions, her right wrist gradually became more painful; and that she suffered excruciating pain in her right wrist which was caused by an attrition fracture of the TFC of her right wrist that occurred towards the end of the third SX that she was performing that morning[223].

109. I repeat what I stated in §37 above that Professor PC Leung and Dr Yeung were in agreement that the plaintiff’s TFC damage could be the result of both structural predisposition and repeated work-related strenuous mechanical stresses. They would not be able to affirm that her wrist problem was solely predisposed by the structural abnormality. They both felt that repeated mechanical stresses on the wrist and TFC could cause chronic damage, particularly so, because of the structural variance of the plaintiff’s right wrist[224].

110. Based on the medical evidence and based on the ergonomic evidence, from which I have concluded that the Strain Index Score in this case is 36, I find, further, that the plaintiff suffered the attrition fracture of the TFC of her right wrist because her right wrist had been weakened and was made vulnerable from the excessive SX that she was assigned to perform from the end of September 1998 to the beginning of October 1999, when she had to take sick leave because of the pain in her right wrist. After her return to work from sick leave, her right wrist continued to be weakened and vulnerable such that when she performed the third SX on the morning of 30 October 1999, she suffered an attrition fracture of the TFC of her right wrist.

111. I refer to my findings in §20 that the plaintiff’s heaviest workload, in terms of SX per session, was during the months of late September to November 1998 being 2.16, 2.15 and 2.0 SX per session for the 3 months. The workload lessened in the subsequent months from December 1998 to July 1999, but the number of SX per session still ranged from a low of 1.54 in May 1999 to a high of 1.81 in February 1999. It appears from the tables produced by Dr Yau Chuen Kam that, from October 1998 to September 1999, the plaintiff had performed 710 SX whilst, over the same period, Dr Sunny Tsui had only performed 479 SX[225].

112. As I noted in §19 above, in her 2nd supplemental witness statement, the plaintiff produced a table of SX per work session during the period she worked in NDH from the end of September 1998 to October 1999[226]. The average number of SX per session was 1.68[227]. However, I found that the average number of SX per session from the end of September 1998 to October 1999 was 1.65[228]. I also noted in §19 above that Dr Yau Chuen Kam[229] gave a breakdown of the work carried out by the plaintiff and Dr Sunny Tsui[230], and a breakdown of the number of non-surgical extractions and SX performed by the plaintiff and 4 comparable dental officers[231]. I quote from the defendant’s Closing Submissions[232] as follows:

“88. On the other hand, extraction figures for comparison are provided by Dr. Yau in [B/11/145]. For the period from Jan 1999 to Sept 1999, the following figures may be obtained:

Name of dentist
Average no. of surgical extractions per session
Drs. KO Hay Ching/ TONG Kwai Shing
0.64
Dr. LUI Wai Kay
0.66
Dr. CHEUNG Chi Tung
0.86”

113. The plaintiff’s average number of SX per session from the end of September 1998 to October 1999 was 1.65. The plaintiff was assigned to perform more than twice as much SX per session as Drs Ko/Tong and Dr Lui, and almost twice as much SX per session as Dr Cheung. I reject the defendant’s submission that the plaintiff’s workload was not excessive because the other doctors had correspondingly more non-surgical extractions to perform whilst the plaintiff had correspondingly less nonsurgical extractions to perform. The Strain Index Score for SX was 36, whilst the Strain Index Score for non-surgical extractions, as assessed by Ms James, was only 13.5[233]. Performing non-surgical extractions does not ameliorate the risk of injury from performing excessive SX.

114. Dr Cham Kwong Man accepted in the course of cross examination that she was aware of the major study, based on 20 years or more of literature on musculo-skeletal disorders and workplace factors, that was called NIOSH[234] for short, and that she had a soft copy of that study in her office. She was also aware of the material contained in chapter 5 and 5a of that study[235] on work-related hand/wrist muscular skeletal disorders (including carpal tunnel syndrome)[236].

115. I agree entirely with the plaintiff’s closing submissions that:

“44. Wrist Injuries are known to be a Work Related Upper Limb Disorder caused by heavy repetitive duties, in this case, wrist movements. CTS, which P suffered, is such an injury which is well known in the literature and the law (Munkman - chapt 19 generally). In 1999 it also became a statutorily reportable injury under Cap 509. D, being a health department, knew or [ought to have known] of the fact that chronic repetitive strenuous dental activities related to wrist movements could cause upper limb musculo-skeletal disorders in dental personnel i.e. wrist injuries (C302) [NIOSH 1997 - C146 and referred to in Burt 2013 at C180, HSE 1990].
45. D knew or ought to have known these facts but deny knowledge. Dr Cham’s evidence shows D knew of and had information on the relevant risks to the wrists of dentists as D had documents and access to advice and information. The Department of Health (DOH) has access to advice from the OSH branch of the Labour Dept and frequent inter action with the Labour Department and would be given copies of relevant materials (4T55-56). These materials would include documents relating to repetitive hand stress and injuries to the wrist and upper arm disorders, which would be deployed as educational materials to raise awareness and prevention. The DoH was pro-active and did not wait to be given information but searched even outside HK (4T56-57). D had a copy of NIOSH (P271) and Dr Cham was aware of the Chapter 5 and 5A material (P283) on hand wrist musculo skeletal disorders (4T89-90).
46. Wrist injuries such as CTS are foreseeable in these work related circumstances, and TFC injury is the same general type of wrist injury, so that D is liable for all types of wrist injuries (including extensor carpi ulnaris (ECU) tendon dislocation). It is no defence to say that the TFC damage is more severe than CTS, so as to be too remote a type of damage for D to foresee and take reasonable precautions against.”[237]

116. In addition to the literature identified in §44, which is quoted above in the preceding paragraph, in her report TJ-1[238], Ms James also identified the paper published in 1987 by Silverstein et al. that found that carpal tunnel syndrome has a high correlation with highly repetitive jobs that require high amounts of exerted force. They found that reducing the force or the repetition appeared to reduce the occurrence of carpal tunnel syndrome. Repetitive motions were particularly problematic when performed using awkward hand/wrist postures. I accept the evidence of Ms James that, at the time of this occurrence, “we knew that there were certain risk factors that would contribute to musculoskeletal disorders such as carpal tunnel syndrome. … the evidence was readily available at that time”[239].

117. I find that the defendant knew or ought to have known that repetitive strenuous dental activities related to wrist movements could cause upper limb musculo-skeletal disorders in dental personnel including carpal tunnel syndrome. I find that it was reasonably foreseeable that the assignment of an excessive amount of SX to a dentist to perform would create an unreasonable risk of injury and damage to the wrist of the dentist assigned to carry out that work.

118. I conclude from the evidence I have reviewed in the preceding paragraphs that the plaintiff was assigned an excessive of amount of SX to perform, being twice and more than twice the amount of SX that 4 other dentists had to perform during the relevant period from the end of September 1998 to the beginning of October 1999. I find that the defendant was in breach of its duty of care to the plaintiff by assigning to her an excessive amount of SX to perform during the period in question.

119. I have found in §48 above that, if damage to the wrist is reasonably foreseeable, reasonable foresight of the extent of damage is not required for liability to attach in negligence; neither is reasonable foresight of TFC damage to the wrist required, nor is reasonable foresight of the precise manner of its infliction required for liability to attach in negligence. Accordingly, I also find that it is not a defence to assert that TFC damage was not reasonably foreseeable and too remote a type of damage for the defendant to take reasonable precautions against.

120. I repeat my findings on causation in §110 above and my findings on causation in §§40-44 above, which apply equally to this ground of liability, namely, the assignment of an excessive amount SX to perform from the end of September 1998 to the beginning of October 1999.

121. For these reasons, I also find the defendant liable in negligence on the alternative ground advanced by the plaintiff, namely, that she was assigned an excessive amount of SX to perform during the period in question.

[size=1em]Quantum

122. The following table sets out in summary form the various heads of loss and damage claimed by the plaintiff and the parties’ differences in respect of these claims:

[td]
Plaintiff Defendant Defendant
(75% discount)
General Damages
PSLA 400,000 300,000 75,000
Loss of congenial employment 150,000 120,000 30,000
Sub-total: 550,000 420,000 105,000
Pre-trial Loss and Expenses
Medical & Therapy expenses 69,978 13,378 3,344.5
Travelling expenses 11,470 7,630 1,907.5
Loss of earnings (after deduction of salaries tax) 8,664,999 6,125,909.5 1,531,477.4
Costs of re-education 177,974 0 0
Costs of care 5,810 5,810 1,452.5
Sub-total: 8,930,231 6,152,727.5 1,538,181.9
Sub-total (after deduction of Employees’ Compensation received): 8,381,8791 5,507,607 893,061
Post-trial Loss and Expenses
Loss of earnings & pension 18,627,970 9,078,540.6 2,269,635.15
Medical expenses/appliances 187,390 6,310 1,577.5
Loss of earning capacity 142,800 142,800 142,800
Sub-total 18,958,160 9,227,650 2,414,012
Interest
General damages 165,000 25,200 6,300
Pre-trial pecuniary losses 6,415,364 1,619,236.61 262,560.19
Sub-total 6,580,364 1,644,436 268,860
Total Damages 34,470,403 16,799,694 3,680,934

(odd cents removed in sub totals for clarity)

1The Plaintiff’s sub-total after deducting Employees’ Compensation, less 15% tax (645,120 x 0.85= 548,352)

[size=1em]Pain Suffering and Loss of Amenities (“PSLA”)

123. I refer to §§2.8 to 2.14 of the joint report of Professor PC Leung and Dr Yeung, which I have set out in §31 above. I also refer to §§32 and 33 above.

124. After the injury to her right wrist on 30 October 1999, light duty was recommended for her. In January 2000, she was transferred to look after school children in the MacLehose Dental Centre. Her main duty was to supervise the work of dental therapists and to assist them in difficult extractions.

125. In November 1999, she sought treatment in QEH. Owing to her persistent pain, MRI of the right wrist was performed in August 2000. She was diagnosed to be suffering from right CTS and right wrist TFCtear. She was treated with splintage, local steroid injection, and physiotherapy. Because of persistent numbness, weakness and pain around the right wrist, a surgical operation was carried out in August 2002 to release the carpal tunnel entrapment, repair the TFC, and relocate the dislocated extensor carpi ulnaris tendon. After the operation, she used a splint for her right wrist and tried to use her left hand to extract teeth. However, this resulted in pain at the ulnar aspect of the left wrist and occasional numbness of the left hand.

126. She was first examined by Professor Leung in December 2002, who reported that her right wrist problems were about 50% resolved, but that, onstrenuous supination/pronation, pain was still felt over the ulnar side of the wrist.

127. The plaintiff was examined by Dr Yeung in August 2003. At that time, she still had pain at the ulnar aspect of her right wrist, weakness of the right hand, and also numbness of the right thumb and fingers at the radial side. Dr Yeung was of the opinion that she had not yet reached maximum medical improvement at that stage.

128. In August 2004, a medical board recommended her to be invalidated because of her right wrist problem and she has ceased work as a dentist since then.

129. In September 2009, the plaintiff was again examined by Professor Leung. Further improvement was noted, and numbness over the right hand was only occasionally felt. The wrist pain would come on strenuous wrist motion, particularly on twisting. Since she stopped her dental practice in August 2004, her own assessment was that she was somewhat 70% recovered.

130. Both orthopaedists agreed that the plaintiff suffered from:

(a)  Bilateral CTS that was more severe on the right side and only transient and mild on the left side;
(b)  Tear of TFC at the right wrist; and
(c)  Dislocation of the extensor carpi ulnaris tendor of the right wrist.

131. After examining the plaintiff in September 2009, Professor Leung was of the opinion[240] that she was no longer suffering from any CTS of the right or left wrists. He was also of the view that that carpel tunnel release was unlikely to give rise to recurrence.

132. Both orthopaedic experts agreed that the prognosis of the TFC injury was worrying. Little further improvement could be expected, though the plaintiff’s condition would not deteriorate either. She had reached maximum medical improvement and no further treatment is indicated.

133. The sick leave granted to the plaintiff before her retirement was considered by both orthopaedic experts to be appropriate. They also agreed that the plaintiff could not resume work as a dentist.

134. I have reviewed the authorities cited to me by the parties on damages for PSLA, including Yip Mau Leung v. University of Hong Kong[241], Bhim Bahadur Rai v. Fung Shing Hong[242], and Ho Kwai Kong v. Cheung Kok[243]. I agree that the closest authority with respect to the plaintiff’s right wrist injury is Cheng Yuk Chun v Winson Cleaning Service Company Limited & Ors[244]. The learned judge appears to have misnamed the triangular fibrocartilage complex in the wrist as the triradiate cartilage in the hip but it is reasonable clear that he was referring to the wrist and not to the hip. In Cheng Yuk Chun in Lee Yau Wai v Yeung Kam Wing[245] Master Marlene Ng, as she was then, gave the following summary of his considerations for his award of PSLA:

“69. …the plaintiff fell and injured her right wrist with miscellaneous laceration and bruise. The facture was treated with close reduction and plaster immobolisation, and she was discharged on the following day. After the plaster cast was removed she received physiotherapy, but the condition was complicated by development of reflex sympathetic dystrophy (RSD) or complex region pain syndrome (CRPS) which resulted in pain and stiffness of the fingers and wrist. Subsequently, tear of triradiate fibrocartilage cartilage and mild carpal tunnel syndrome were discovered. When the RSD symptoms resolved gradually, the plaintiff was readmitted for wrist arthroscopy and debridement of the triradiate fibrocartilage cartilage tear, and was discharged days later. Movement of the right wrist was almost full with residual limitation. The plaintiff was at the end stage of CRPS with slight muscle wasting of right forearm but no entrapment neuropathy of the forearm nerves. With continued use of her right hand, prognosis was optimistic. The plaintiff was also found to suffer from adjustment disorder with depressed mood, and required further psychiatric treatment for 1-2 years. Whole person impairment for physical and psychiatric disability was 5% and 5-10% respectively. She could return to her pre-accident work as a cleaning worker with some initial difficulty in handling heavy weight or possible difficulty in relation to her mental symptoms. The PSLA award was HK$300,000.00.

135. In David John Slater v. Commissioner of Police[246], I held that awards for damages for PSLA in personal injury cases falling within the Serious Injury category would start at $530,000 as at July 2017. In July 2007, when Cheng Yuk Chun v Winson Cleaning Service Company Limited & Ors. was decided, awards for damages for PSLA in personal injury cases falling within the serious injury category started at $390,000[247]. The increase in the level of awards in the 10 years from 2008 up to the current level of awards has been to the order of about 36%. Applying the same percentage of increase to the award of $300,000 would produce an award of about $400,000 today.

136. However, it should be noted that the award in Cheng Yuk Chun v Winson Cleaning Service Company Limited & Ors was not only for the wrist injury but also for the plaintiff’s adjustment disorder with depressed mood. On my reading of the said judgment, I am of the view that the award of $300,000 could be apportioned, as to $225,000 thereof, in respect of the wrist injury; and as to $75,000 thereof, in respect of the psychiatric condition. I would award the plaintiff in the present case, damages for PSLA in the amount of $300,000 for the damage that she suffered to her right wrist.

[size=1em]Alleged psychiatric injury

137. The plaintiff also claims damages for PSLA for “depression and stress disorder requiring continuing psychiatric care”[248]. The defendant has denied the claims for psychiatric injury, only allowing $300,000 as damages for PSLA and denying the claims for pre-trial and post-trial cost of psychiatric treatment[249]. It was submitted in the defendant’s closing submissions that the claim for damages for psychiatric and psychological injuries ought not to be entertained as no expert evidence had been adduced in support thereof[250].

138. I had refused the plaintiff’s late application for leave to adduce expert psychiatric evidence. At the last Check List Review Hearingon 2 September 2016, I reiterated that I was not permitting the plaintiff to adduce expert psychiatric evidence[251]. These proceedings were started in 2002 and the need for such evidence was apparent as early as January 2003, when the plaintiff started to consult a psychiatrist[252]. The reasons I relied upon, on 15 September 2014, for my refusal to allow the plaintiff’s late application to adduce expert evidence from Professor Cheung Lim Kwong on issues of liability, applied equally to my decision to refuse to allow the plaintiff’s late application to adduce expert psychiatric evidence:

“2. These proceedings were commenced as long ago as 2002 and relate to matters that happened in 1998. The proceedings have had a chequered history and whilst, sadly, many cases prior to the Civil Justice Reform (“CJR”) limped along in this tardy way, there has been a sea-change since the CJR was enacted, and even before that, with the enactment of Practice Directions governing personal injury cases.
…
27. Nevertheless, it must be accepted that it cannot be said that the expert evidence to be adduced from Professor Cheung could not be relied on by the court in the determination of the ultimate questions posed in this case. If the application to adduce Professor Cheung’s evidence had been made much earlier in the day, or had been made, even late in the day but before the implementation of CJR, there was clearly some likelihood of that application being allowed. But those days are gone.
…
30. I have to have regard to those matters but I also have to take on board the provisions of the CJR and the many, many cases which have been handed down in the context of late applications to adduce expert evidence, including, of course, my decision in Fung Chun Man v Hospital Authority. Having done so, I come very firmly to the view that this is not a proper case in which I should grant the plaintiff the indulgence to adduce expert evidence so late in the day.
31. The reasons for the delay advanced in his affidavit by Mr Clancey, the plaintiff’s solicitor, did not move me to exercise my discretion in the plaintiff’s favour by granting leave to adduce expert evidence from Dr Cheung.
32. To allow her do so, so late in the day, would, in my view, run a horse and carriages through all those decisions in which I have tried to set a level playing field for all parties and in which I have tried to set a standard of conduct of PI litigation which promotes justice in the sense of expedition, and proportionality, and the saving of costs.”[253]

I had refused to allow the plaintiff’s late application to adduce expert psychological evidence in Fung Chun Man v. Hospital Authority & Or. for similar reasons:

“45. Balancing the impact of the psychological evidence on the quantum of the plaintiff’s claims; the cost implications of allowing Professor Peter Lee’s report to be adduced and granting leave to the defendants to obtain a report from their nominated psychologist, with the consequent need for a further joint report from the psychologists; the likelihood of the trial dates being derailed by this process or, at the very least, the trial being lengthened by the additional expert evidence which is likely to be contentious, particularly as regards the cause of the plaintiff’s current psychological condition, if any, I had little hesitation, seeing that the application was made so late in the day and at the eve of trial, to dismiss it. In this case, the expert evidence sought to be adduced is from a recognised discipline. The evidence is reasonably required to enable me to resolve the issues in dispute although, for the reasons explained above, I would not be seriously affected in my ability to resolve this case without that evidence. I am also prepared to accept that the costs of adducing such evidence are proportionate, perhaps just barely proportionate, to the sums at stake. However, the potential disruption to the trial, and the absence of a good explanation for the late application, have led me conclude that I ought to dismiss this application.”[254] [Emphasis added]

139. In the absence of an admissible expert report from a psychiatrist, the plaintiff relies on the plaintiff’s treating doctors’ reports[255] and her own evidence[256] in support of claims for damages for “depression and stress disorder requiring continuing psychiatric care”. The reliance on treating doctors in personal injury claims was commented upon by Deputy High Court Judge Gill in Siu Leung Shang Peter v. Chung Wai Ming[257]:

“27. The first concerned the status of Dr Kuan. He is not a registered orthopaedic with recognized expertise in the field. On his own account, he has not before given expert testimony in court. More seriously, since August 2004 Mr Siu has been his patient, so that opinion from him whether expert or not might not have the necessary objectivity that would be forthcoming from an independent practitioner. This is particularly important in personal injury cases, where as far as possible the plaintiff’s subjective account should be tested to avoid or at least reduce the risk of his exaggerating his symptoms.”

A more fundamental objection to the use of treating doctors’ reports is that opinion evidence is only admissible with leave of court. I addressed the court’s role in controlling the receipt of expert evidence, in Fung Chun Man v. Hospital Authority & Or.[258], in these terms:

“6. The court’s control over medical evidence in personal injury cases was evolving long before the court’s case management powers were created by the CJR. The evolutionary process, initiated by the need to ensure cost efficient and speedy resolution of personal injury litigation, resulted in the adoption of a joint approach, both at the pre-action and at the post-writ stages, of obtaining and deploying expert medical evidence for use at trial. The tri-partite benefit of such an approach, to the courts and to the parties concerned, cannot be denied. …
…
9. The enactment of the CJR did not result in a change to O.38, r.36 of the Rules of the High Court (“RHC”). However, after the enactment of the CJR, it is clear that the court’s discretion, whether or not to grant leave to a party to adduce expert evidence, is to be exercised within the ambit of the court’s management powers. Those powers must be exercised in the light of the underlying objectives of the CJR, including the need to ensure the cost effectiveness of the proceedings; to ensure that the case is dealt with expeditiously; to ensure reasonable proportionality having regard to the amount of money involved, the importance of the case, the complexity of the issues, and the financial position of each party; to ensure procedural economy in the conduct of the proceedings; and to ensure fairness between the parties.
10. The courts recognise that the primary aim of its case management powers is to secure the just resolution of the dispute in accordance with the substantive rights of the parties. However, the substantive rights of the parties to a personal injury action do not include a legal right to call experts of their choice.
11. The expert evidence can only be adduced with leave of the court and, in deciding whether or not to grant leave, the court must ensure that such evidence is admitted only if it is likely to be of real assistance to the determination of the issues, and that it is adduced in the most effective and economic way consistent with the objectives of the CJR.
…
15. In summary, the expert evidence must be in a recognised discipline, reasonably required to enable the court to resolve the issues in dispute, and proportionate.
16. However, even if a prima facie case is made out for the admission of expert evidence, in every case, the court must also have regard to other relevant circumstances...[and]... the underlying objectives of the CJR: to ensure cost effectiveness and economy, expedition, proportionality, and fairness between the parties. Ultimately, the court strives to do justice between the parties and, in cases where the court permits the parties to call expert evidence, the court strives to ensure a level playing field with fair access to proper experts for all parties.
17. These objectives and the joint approach are reflected in the protocol for commissioning expert reports set out in section I of the Personal Injuries List Practice Direction PD18.1. Of particular relevance are the general provisions §§69-71, reproduced as follows:
“69. As a general rule, leave of the court or consent of the parties is required before any expert evidence can be adduced at trial.
“70. A party who obtains expert evidence before obtaining leave, other than from a single joint expert or pursuant to joint examination and joint expert report with the expert(s) of the other party or parties, does so at his own risk as to costs and/or eventual refusal of leave to adduce such expert evidence.
“71. As soon as it is realized there exists a need or an anticipated need for adducing expert evidence at trial or if parties failed to reach agreement on arranging joint examination and/or compiling joint expert report by the parties’ respective experts before or after the commencement of proceedings or if no agreement can be reached as to directions on obtaining expert evidence and/or for permission to adduce expert evidence, a party shall apply (by inter partes summons or by restoring the case for Check List Review Hearing) or the parties shall jointly apply (by Consent Summons to expedite or restore the hearing of the Check List Review) to the PI Master as soon as possible upon the commencement of or in the course of proceedings, as the case may be, for directions on obtaining expert evidence and/or for permission to adduce expert evidence.” [Emphasis added]
18. It must be emphasised that the courts do not purport to control or inhibit a party’s right to consult experts and to obtain reports from them. The party with means may do so. The party, not under disability, who has obtained an interim payment, may deploy part of that payment towards the costs of such experts. In a recent case involving a plaintiff who was either in a permanent vegetative state or minimally conscious state, I indicated that I might be willing to grant leave for part of the interim payment received to be used in obtaining a functional MRI report to ascertain the true level of consciousness of the plaintiff. In a legal aided case, such as the present one, the plaintiff or his legal advisers may be able to persuade the Director of Legal Aid to grant permission to obtain an expert’s report. However, the point to emphasise, as reflected in §70 of PD18.1, is that, whilst a party is free to obtain his own expert report, he does so at his own risk as to costs and possible refusal of leave to adduce such expert evidence. In addition, parties need to know that non-compliance with PD18.1 and the pre-action protocol set out therein without good reason may result in adverse costs consequences and sanctions, including wasted costs orders (see §9 of PD18.1).
19. Another point to emphasise is that the party who obtains an expert’s report, without agreement of the other party and without leave of court, runs the risk of disqualifying that expert from appointment by the court as the single joint expert. The risk may not be high at the beginning of proceedings when the court, although refusing leave for the party to adduce his solo expert report, may be amenable, nevertheless, to grant leave for a joint examination to be carried out by the expert concerned in conjunction with the expert nominated by the other party, and for a joint report to be prepared by them. However, if application is made, late in the day and when trial is imminent, for expert evidence to be adduced, the court may refuse the application or may only allow it on the basis of a single joint expert being appointed. [Emphasis added]
…
23. There appears to be a misconception that the courts will not readily grant leave for evidence from a psychiatrist or a psychologist to be adduced. The law of negligence does not provide a remedy for distress which does not amount to a recognised psychiatric illness9, unless the distress, anxiety or fear is accompanied by a physical injury.10 The courts award damages where a party has suffered a recognisable psychiatric illness over and above emotional distress and disquiet. The court will almost invariably require expert evidence to determine whether or not this is the case11. Even where it is not disputed that the plaintiff suffers from psychiatric illness, there may be a dispute as to causation: was the psychiatric illness caused or contributed to by the tort complained of. A trial judge who has to determine this issue of causation may need assistance from an expert in this field.
9 Wainwright v. The Home Office [2004] 2 A.C. 406; Hinz v. Berry [1970] 2 QB 40; Hicks v. Chief Constable of South Yorkshire Police [1992] 2 All ER 65; Reilly and Reilly v. Merseyside Regional HA [1995] 6 Med LR 246
10 Berhens v. Bertram Mills Circus Ltd. [1957] 2 QB 1; H. West & Son Ltd. V. Shepard [1964] AC 326, Kralj v. McGrath [1986] 1 All ER 54
11 Mullins v. Gray [2004] EWCA Civ 1483, at para. 12
24. Indeed, in most cases, the need for psychiatric treatment or psychological counselling is apparent long before the commencement of proceedings. Inappropriate conduct or speech is noted by family members or recorded on the hospital records. Prolonged sadness, excessive anxiety, unusual irritability and temper tantrums are all indicia of possible psychiatric illness. These are often recognised by treating doctors and nurses and the patient referred to a psychiatric unit, whether in-patient or out-patient, for assessment and treatment. Even if the hospital records or treating doctors and nurses make no mention of a plaintiff’s psychiatric illness or possible psychiatric illness, orthopaedic or neurological experts examining a plaintiff in order to prepare expert medical reports on his physical condition will often recognise the presence of a psychological or psychiatric component and recommend that reports be obtained from relevant experts in that field. Each case must depend on its own facts and a mere recommendation without supporting reasons by an expert from another field may be insufficient, but where the need for psychiatric or psychological evidence is clear and obvious, there can hardly be any realistic challenge to a request for relevant expert examination and reporting.
25. In other cases, where there is no apparent indicia of a psychological component in addition to the physical injuries suffered by the plaintiff, the request for leave to adduce evidence from a psychiatrist or a psychologist will need to be properly justified. Such justification may be provided by submitting a written note from the intended expert setting out brief reasons explaining why the expert opinion is necessary in the particular case. However, for the reasons set out in §§18 and 19 above, a full medical examination and report should not be commissioned without agreement from the other party or leave of court.
26. If the request is made late in the day, or close to the commencement of trial, it is likely to be refused even if justified. As Brooke LJ explained in Baron v. Lovell [2000] PIQR P20, each party is afforded an opportunity by the rules to make a well informed valuation of the claim and a well informed Part 36 offer (or, in Hong Kong, a sanctioned offer). The regime simply will not work if the former latitude in serving late evidence is allowed to persist. It is quite wrong for a trial to be delayed, and for the possibility of making an effective Part 36 offer (or, in Hong Kong, a sanctioned offer) to be rendered nugatory, because of the late service of an expert’s report.” [Emphasis added]

140. In Hung Sau Fung v Lai Ping Wai[259] I explained that:

“46. A report of a treating doctor is always admissible to prove the fact that the injured person was receiving treatment, the nature of that treatment, and the opinion and diagnosis of the treating doctor which was communicated to the injured person. These are all matters of fact. Whilst the diagnosis reached and the treatment plan recommended by the treating doctor is the product of his expertise, his diagnosis and treatment plan and their communication to the injured person is a matter of fact. However, the opinions expressed by the treating doctor in his report are not admissible as expert evidence unless leave to admit it for that purpose has been obtained from the court. ……”

141. I re-iterated the Court’s role and the exercise of its case management powers in this regard in my recent decision in Tang Tak Ping v. Kai Shing Construction Co. & Ors.[260]:

“11. The court’s discretion, whether or not to grant leave to a party to adduce expert psychiatric evidence, is to be exercised within the ambit of the court’s management powers. The court must ensure that such evidence is admitted only if it is likely to be of real assistance to the determination of the issues, that its cost is proportionate to the importance of the issue in question and the amount involved, and that it is adduced in the most effective and economic way consistent with the objectives of the Civil Justice Reform. In Leung Kang Wai v. Dussmann Service Hong King Ltd. (HCMP 2098/2011, 29 December 2011), the Court of Appeal refused to grant leave to appeal against the master’s exercise of discretion in what was essentially a case management decision in a case where the causal link between the alleged tort and the psychiatric illness complained of was tenuous, the cost of obtaining such evidence was disproportionate, and the grant of leave to adduce such evidence would be contrary to the need to ensure cost efficient and speedy resolution of the personal injury litigation in that District Court case.
12. In other cases, such as the recent case of Maxwell v. Keliston Marine (Far East) Ltd. & Anor (HCPI 945 of 2003, 20 January 2012) and this one, where the treating doctor simply makes a bald assertion that the depression or other psychiatric condition was caused by the alleged tort, the court may require the assistance of a forensic assessment by an expert psychiatrist before it can be satisfied that a causal link between the tort and the psychiatric illness has been established. Even so, the court should not grant leave, if the cost of obtaining such evidence was disproportionate and the grant of leave to adduce such evidence would be contrary to the need to ensure cost efficient and speedy resolution of the action.”

142. In her decision in Lau Mei Wa v. Li King Yin & Or[261], MasterMarlene Ng, as she then was, made it clear that treatment records were insufficient and that the court required assistance from expert psychiatric evidence:

“143. … Whilst [Mr Sakhrani] did not disagree there was a psychiatric component to the plaintiff’s medical condition after the Accident and he frankly accepted she received psychiatric and clinical psychological treatment after the Accident for mild depression, he contended that the Medical Records and Reports and the plaintiff’s own evidence as to her depressed mood would sufficiently enable the trial judge to make findings on the course of the depression (eg the type and severity of the psychiatric symptoms displayed by the plaintiff before and after the Accident) and on the plaintiff’s present psychiatric condition, and to draw conclusions as to the cause of her depressed mood, the psychiatric diagnosis and the severity of the symptoms. On such basis, Mr Sakhrani urged this court to decline granting leave for the plaintiff to adduce psychiatric expert evidence, and further argued that this court should direct the plaintiff to obtain up-to-date treatment reports from PMH and WKPC.
144. Plainly, there is a psychiatric component to the plaintiff’s claim for loss and damages in the present proceedings. Mr Sahkrani’s submissions in the above paragraph tried to present such aspect of the plaintiff’s claim as a question of fact for the trial judge by weighing and assessing the treatment, surveillance and witness evidence without any need for psychiatric expert opinion. The question is therefore reduced to whether the assessment of loss and damages in respect of the psychiatric component of the plaintiff’s claim is purely a question of fact or whether the trial judge will be assisted by psychiatric expert opinion when weighing the evidence and coming to his/her conclusions on the ultimate issues.
145. The starting point is this. It is normal human experience to feel unhappiness and ordinary emotions of grief in the face of adversity, and parties can credit the trial judge with some common sense appreciation of any anxiety and/or other normal emotional reaction consequent upon physical trauma. It is also common knowledge that some persons do not develop psychiatric condition/reaction in response to even the most serious traumatic event or the most extreme stressor, but some unfortunately do. The plaintiff has to establish not only a diagnosable psychiatric condition that is legally attributable to the tort complained of but also clinically recognised treatment consequent upon such condition in order to maintain a claim for damages for psychiatric distress and for the cost of psychiatric or clinical psychological treatment.
146. Here, although Mr Sakhrani fairly accepted that the plaintiff had depressive symptoms after the Accident for which she received psychiatric and clinical psychological treatment, and he further suggested that Dr Kwan’s diagnosis of mild Major Depressive Disorder did not differ from the diagnosis of mild depression by WKPC’s Dr MW Ng for the purpose of assessing damages, his submissions fall shy of acknowledging that the plaintiff has suffered and/or is still suffering from any diagnosable psychiatric illness that is attributable to the Accident. Given that the plaintiff carries the burden of proving her claim, it is,in my view, plain that psychiatric expert evidence is required in the present case. There is also the further question whether (as so readily suggested by Mr Sakhrani) mild depression is the same as Major Depressive Disorder is terms of psychiatric diagnosis, medication, therapy and/or prognosis. I am not persuaded that the answer to this question is merely a matter of fact and not of medical opinion.”

143. More recently, Deputy High Court Judge, Marlene Ng, as she then was, reiterated the same principles in Pak Siu Hin Simon v. J V Fitness Ltd[262]:

“69.  Secondly, Mr Wong SC cast doubt on Ms Chhoa’s heavy reliance on P’s alleged psychiatric injuries/disabilities.  The starting point was the absence of psychiatric expert evidence in the present action.  Despite Ms Chhoa’s suggestion that P’s psychiatric complaint was even greater than his physical injury, P never asked for leave or consent to adduce psychiatric expert evidence (even though Dr Tio recommended psychiatric expert assessment), and in P’s latest PI Questionnaire dated 1 December 2014 he still maintained that his sole medical expert was Dr Tio.  Mr Wong SC submitted it was not open to P to say he should have recovered damages for his alleged psychiatric condition “as there is simply no admissible evidence that [P] suffered any psychiatric illness, let alone any evidence to show that the accident was the cause of any psychiatric illness allegedly suffered by [P]”.  Although P did produce factual psychiatric/psychological treatment evidence that referred to a diagnosis of panic disorder, Mr Wong SC argued such factual evidence did not equate to expert opinion as to whether the Accident was the operating cause of P’s psychiatric complaints or whether such complaints would have prevented P from returning to his pre-Accident work.24  Mr Wong SC further argued since P had no intention to adduce psychiatric expert evidence, there was no basis to translate the factual psychiatric treatment evidence into an award of damages for psychiatric sequelae arising from the Accident.
70. In my view, to sustain a claim for damages for psychiatric injury (including compensation for psychiatric distress and costs for psychiatric/psychological treatment), the burden is on the plaintiff to establish not only a diagnosable psychiatric condition25 that is legally attributable to the tort complained of but also a need for clinically recognised treatment consequent upon such condition.26 The fact that psychiatric treatment records/reports are available does not ipso facto mean psychiatric expert evidence becomes unnecessary.27  Here, even though P presented with psychiatric symptoms, and received and continued to receive psychiatric/psychological treatment (including psychotherapy and pharmacological intervention) after the Accident, and Dr Tai and Dr Ng diagnosed that P suffered from panic disorder, it is quite plain D denied any psychiatric injury/disability were attributable to what D considered to be minor physical trauma as a result of the Accident (especially on D’s version of how the Accident happened), and a trial judge may need psychiatric expert evidence to determine the dispute over causation.28  Where the treating doctor simply makes a bald assertion that the psychiatric condition was caused by the alleged tort or where (as here) the treating psychiatrist only gave the diagnosis and treatment history without critically evaluating the causative nexus between the psychiatric condition and the accident,29  it is likely that the court will require forensic assessment by a psychiatric expert as to the attributable cause(s) in determining whether a causal link between the tort and the psychiatric illness has been established.30
71. This need for psychiatric expert evidence to address on the issue of causation stems from the difference between therapeutic psychiatric expert evidence (eg letters/report by Dr Tai and Dr Ng) and forensic psychiatric expert evidence as explained by Bharwaney J in Hung Sau Fung v Lai Ping Wai:31
“46. …”[263]
Further, absent opinion from a psychiatric expert on the prognosis of any psychiatric consequence following the Accident, there would be difficulty for P to advance claims for costs of future psychiatric and/or clinical psychological treatment and/or damages for loss of earnings and/or loss of earning capacity that might be caused by the alleged psychiatric sequelae.  The essential features of future psychiatric prognosis and treatment (which on P’s case were significant components of his claim for damages for PSLA) could not be resolved by just considering the historical or even updated psychiatric treatment reports/records.
72. This is an important consideration for the present purpose (and indeed for the case as a whole) since Ms Chhoa suggested P’s psychiatric injury was even greater than the physical damage.  D put such assertion into question and cast doubt on the genuineness of P’s psychiatric complaints.  This again highlights the importance of forensic evaluations by psychiatric experts in contra-distinction to clinical assessments by psychotherapy professionals.32 I have summarised the distinction in Bai Siba Kumar as follows:33
“64. Such difference has been further explained in paragraphs 148-152 of my decision in Lau Mei Wa. Whilst it is correct to say that psychotherapists normally adopt a non-judgmental attitude within a doctor-patient relationship in respect of the patient’s account of his/her medical history, complaints and symptoms, the same cannot be said for the psycho-legal expert who is obliged to carry out an impartial evaluation in a forensic context for the purpose of litigation. Such expert is ultimately answerable to the court and not to the patient, and is therefore bound to make an objective and dispassionate assessment of the psycho-legal issues relevant to the litigation by testing rival diagnostic hypotheses to ascertain the psychiatric fallout as a result of the index incident and by subjecting the information from and/or about the claimant to critical scrutiny, eg by seeking verification or corroboration from (a) historical/updated treatment notes/records and reports, (b) forensically-focused mental state examinations conducted by the expert, (c) collateral interviews with family members and/or (d) witness statements. The object is to see whether the claimant’s assertions can be supported or should be refuted, and to consider whether the claimant is dissembling or not. Hence, as explained in Ngai Ping Kwan, it is not unusual for therapeutic and forensic decision-making to differ, and it is not a rarity to come across psychiatric expert reports that conclude that the claimant is a malingerer with no diagnosable psychiatric illness. For example, critical evaluation by the defendant’s psychiatric expert in Ho Man Fong v Sime Darby Motor Services Limited led her to the opinion that the plaintiff in that case had exaggerated her symptoms such that her complaints could not be relied upon for a useful diagnosis. In that case, the trial judge preferred the opinion of the defendant’s expert that there was no psychiatric disorder, especially post-traumatic stress disorder.
65. The aforesaid distinction between treatment and forensic psychiatric expert evidence should allay concerns that knowing claimants might “invent” subjective symptoms to fit in with the clinical presentation of recognisable psychiatric illnesses. Whilst I accept that cross-examination of a claimant on his professed complaints/symptoms might to some extent expose any such “inventions” or alternatively affirm the veracity of such complaints, it is still often necessary to have the benefit of critical evaluation from a medical perspective to assist the trial judge in forming a view as to whether the criteria for a recognisable psychiatric condition have been satisfied.
66. In the circumstances, I do not agree that there is not a lot more that a psychiatric expert can add to the psychiatric treatment records/reports. In a case where there is real possibility of psychiatric consequence, absent such evidence the claimant may be handicapped in advancing claims for cost of future psychiatry/psychology treatment that may be caused by such psychiatric sequelae. This is an important consideration in the present case because there is no suggestion that psychiatric treatment/medication have ceased. In my view, the essential features of future psychiatric prognosis/treatment in the present case cannot be resolved by just considering the WPC 1st and 2nd Reports or even updated psychiatry/psychology records/notes/reports from WPC and QMH on current treatment/medication.
67. Ultimately, the relevant consideration is whether on the particular factual and medical matrix of the present action psychiatric expert evidence is required to assist the trial judge in his adjudication. In my view, there can be no doubt that psychiatric expert evidence is required. Given the challenge by the Ds as to (a) the existence of any psychiatric condition on the part of the plaintiff, and (b) if there is such psychiatric condition, its causation, chronicity and future prognosis, psychiatric expert evidence is relevant. If there is a recognisable psychiatric illness, there are further questions as to the scope and length of future treatment, the proper sick leave for psychiatric injury, and the impact of such condition on work capacity.
24 eg Dr Tai’s referral letter dated 18 August 2013, and Dr Ng’s referral letter dated 26 March 2014 and medical report dated 17 June 2014
25 see Fung Chun Man v Hospital Authority & anor HCPI1113/2006, Bharwaney J (unreported, 24 June 2011) paras 23-24 cited in Lau Mei Wa v Li King Yin & anor HCPI527/2011, Master Marlene Ng (unreported, 13 July 2012) para 111 and in Bai Siba Kumar v Nishimatsu Construction Company Limited & anor HCPI883/2012, DHCJ Marlene Ng (unreported, 8 October 2013) paras 56-58
26 see Lau Mei Wa at paras 145-146 and Bai Siba Kumar para 55
27 see Lau Mei Wa at paras 140-142
28 see Fung Chun Man at para 23, Bai Siba Kumar at paras 59-61 and Lai Yuk Shim v Hung Ling Kwok [2013] 1 HKLRD 580, 582-583
29 see Dr Tai’s referral letter dated 17 August 2013 which merely gave the diagnosis of panic disorder and the medication prescribed, and Dr Ng’s referral letter dated 26 March 2014 and his medical report dated 17 June 2014 which gave P’s premorbid condition, diagnosis and treatment history
30 see Tang Tak Ping v Kai Shing Construction Co [2012] 1 HKLRD 1093, 1103 cited in Lau Mei Wa at para 109
31 [2012] 1 HKLRD 1, 28 cited in Lau Mei Wa at para 147 and Bai Siba Kumar at para 63
32 see Lau Mei Wa at para 149 citing Wu Leung Kui Jacky v Leung Ming Yun & ors DCPI1154/2008, HHJ Mimmie Chan (as she then was) (unreported, 7 March 2011) para 62, Pun Kwong Cheung v Tang Shiu Wo trading as Luen Yick Decoration & Design Co & anor HCPI587/2008, Master Marlene Ng (unreported, 23 February 2010) paras 54-57, and Ngai Ping Kwan v Choi Yat Hung HCPI537/2010, Master Marlene Ng (unreported, 15 September 2011) paras 59-63
33 see also Lau Mei Wa at paras 150-163 and Ngai Ping Kwan at paras 59-63”

144. I have no hesitation in concluding that the plaintiff became extremely unhappy about the loss of her career as a dentist, and suffered much anxiety and distress arising from the need to change her career and the uncertainties she faced going forward. However, in the absence of admissible psychiatric opinion evidence, I am unable to find that she suffered from a recognizable psychiatric illness. The recommendations in the occupational therapists’ reports of Ms Alice Tsang and Dr Cecilia Li that the plaintiff should seek help from a psychologist or psychiatrist and their reference to the treating doctors’ diagnosis[264] do not convert the treating doctors’ reports into admissible psychological or psychiatric expert opinion evidence[265]. Specifically, the administration by Dr Cecilia Li of the Beck Depression Scale, which is a self rated questionnaire, and the resulting assessment that, although she “scored 29/103 from the Beck Depression Scale ... showing that her present state was stable”, the plaintiff “was found to have some psychological problem”[266], does not constitute admissible psychological or psychiatric expert opinion evidence. However, even without such evidence, I am able to take into account her emotional distress, unhappiness and anxiety that she suffered to increase the award of PSLA that I make in this case to $325,000.

[size=1em]Damages for loss of congenial employment

145. The claim for loss of congenial employment is well established as “… a separate head of damage and an award may be made when the Plaintiff has had to give up a job which he enjoyed and which gave him satisfaction and/or status.”[267] This is an award of general damages and is distinct from an award of special damages for past loss of earnings and an award for damages for future loss of earnings and/or damages for loss of earning capacity. The following cases illustrate the awards that have been made in Hong Kong under this head of claim:

a.  Wong Shek Mui v Mammoth Holdings Ltd HCPI 1291/2003, 16 February 2007 ($65,000 to the Plaintiff “who started off to work as a cleaner and became a skilled baker”);
b.  Lam Chu v Tse Lum Wong & Another HCPI 626/2003, 21 September 2004 (about six months’ wages i.e. $30,000 to a toll collector who regarded the job as of particular importance to her even though the job itself was not special);
c.  Lee Kit Ha v The Kowloon Motor Bus Company (1933) Limited HCPI 539 of 2000, 7 October 2002 ($80,000 to a female bus driver: the judge was satisfied that this work meant a great deal to her and that she looked forward to pursuing it until normal retirement);
d.  Wong Sau Lai v Cathay Pacific Airways Limited HCPI 111 of 2002, 24 October 2003 ($120,000 awarded to a “glamour girl” cabin attendant of Cathay Pacific Airways who could no longer pursue her “dream job”); and
e.  Lai Jianxing v Sakoma (HK) Ltd [2012] 5 HKLRD 589 CAVC 220 2011, 19 October 2012 (RMB100,000 awarded to the plaintiff who had been a seaman for 22 years and the deputy captain of a barge, a position that commanded respect and give him much job satisfaction; as a result of his injuries, he took up the lower position of chief mate on the tugboat which undermined his self-esteem).

146. The plaintiff’s career has been ruined and she is saddened by the fact that she will never be able to return to the practice of dentistry[268]. I find that the plaintiff has suffered a real loss arising from the abrupt end to her career as a dental professional which she had pursued for 8 years. She had completed her Master’s degree and aimed to become a prosthodontist, a goal that has been denied to her. I award $150,000 as damages for loss of congenial employment.

[size=1em]Discount for pre-existing vulnerability

147. The defendant seeks a discount of 75% on account of the plaintiff’s double vulnerability: 1mm ulnar variance in the right wrist and the greater variance and greater propensity to develop carpal tunnel syndrome in the left wrist[269]. I can deal with this issue very briefly.

148. I remind myself of the principle that the assessment of damages will take account of any pre-existing disorder or vulnerability and of the chance that the plaintiff would have succumbed to a stress-related disorder in any event[270]. I also remind myself of the 3 scenarios set out in Chan Kam Hoi v Dragages Et Travaux Publics[271]:

“When considering the effect of a pre-existing condition on an award of damages there are three possible scenarios. The first is where the Plaintiff was almost certain to have gone through life unaffected by the condition. The second is where there is a strong possibility that some other event, or natural progression of the condition, would have brought about the Plaintiff’s present state. The third is where this would certainly have occurred at some stage in any event. In the first, the Defendant would be liable for all damage caused. In the second it would be necessary to assess the degree of the possibility in deciding what reduction is appropriate, as in assessing the effect of other vicissitudes of life. In the third, clearly an allowance has to be made, the extent of which depends on the evidence as to when the precipitating event would have occurred.” [Emphasis added]

In Yu Wai Kan v. Law Cho Tai[272], Master Marlene Ng, as she then was, explained:

“71. …
(f) Where a pre-existing condition is likely to lead to disability and loss in the absence of the injury for which the plaintiff is entitled to recover, the usual method of assessing the recoverable loss is to take account of the risks by an appropriate assessment of general damages. Past loss of earnings may also be reduced if the risks during the years concerned are sufficiently high. For future loss of earnings, a reduced multiplier is usually the most accurate way of giving effect to the findings on the medical evidence, especially when a plaintiff’s working life is likely to be limited by a pre-existing condition (see Chan Kam Hoi at p.529 and Cheung Fat Tim v Wong Siu Ming trading as Kee Construction Company & anor HCA 5079/1991, Findlay J (unreported, 17 January 1995)).”

149. Is there a is a strong possibility in the present case that that some other event, or natural progression of the condition, would have brought about the plaintiff’s present state? In the context of the present case, some other event would be the continued practice of dentistry pursuant to which the plaintiff would need to undertake repetitive strenuous dental activities using her hands and wrists which could cause upper limb musculo-skeletal disorders, including carpal tunnel syndrome.

150. It was submitted on behalf of the plaintiff that she was not going to be pursuing these strenuous dental activities for the rest of her working life: she was going to become a prosthodontist, which meant doing sophisticated repairs, not doing the strenuous day-in and day-out two or three SX, or whatever was assigned to her[273].

151. It was the plaintiff’s evidence that after she received her Master’s degree in Prosthetic Dentistry in 1996, she had been planning to pursue a specialist pathway. As part of the requirement for the exit examination in that speciality, she had to work in a recognised institution such as the Hospital Authority and the Government Dental Service or under a qualified trainer for at least 3 years or until she had sufficient clinical experience. Although she had published 2 academic papers in the Journal of Oral Rehabilitation, she could not realise her aspiration to gain her specialist qualification in Prosthetic Dentistry because of the injury to her right hand in 1999.[274] By October 1999, she had almost completed 3 years of clinical practice after her graduation with a Master’s degree in Prosthetic Dentistry.

152. Dr Yau Chuen Kam produced a booklet called “The Guidelines for Accreditation and Training in Prosthodontics”[275]. The defendant has conceded that the plaintiff was at level 5 of the sequence of training set out in the guidelines, having completed her Master’s degree[276]. The guidelines set out final levels of training as follows:

“6. Year 5 and 6 should be structured higher training period in an approved program at training institute or approved practice in conjunction with a training institute.
7. Before accreditation as a trained specialist, the candidate, having fulfilled all other requirements of speciality training as determined by the Speciality Board in Prosthodontics, must also successfully complete an Exit Examination in Prosthodontics conducted by the College of Dental Surgeons of Hong Kong.
8. Final exit examination (Appendix III[277])”

153. I accept the plaintiff’s evidence that she wished to become a prosthodontist and that she was well on her way towards completing her training programme. I find, on a balance of probabilities, that, if she had not suffered the TFC injury to her right wrist in October 1999, she would have qualified as a prosthodontist and worked as such no later than 3 to 4 years from October 1999. I refer to §§2 to 4 and 11 above. I had found that, prior to working at NDH, the plaintiff did not experience any numbness or other symptoms in her right hand and wrist, either from dental work or from any other cause in the course of almost 7 years of practice as a dentist from February 1990 to September 1998[278]. I also find that, if she had not suffered the TFC injury to her right wrist in October 1999, there was only a remote possibility that her continued practice of dentistry in the 3 or 4 years after October 1999 would have brought about the plaintiff’s present state. The work of a prosthodontist does not require her to undertake repetitive strenuous dental activities using her hands and wrists which could cause upper limb musculo-skeletal disorders, including carpal tunnel syndrome, and would not have posed any risk to her pre-existing vulnerability. Accordingly, I do not discount the damages I award on account of a pre-existing vulnerability.

[size=1em]Pre-trial loss and expenses

154. The differences between the parties under this head of claim are set out below:

[td]
Pre-trial Loss and Expenses Plaintiff Defendant
Medical & Therapy expenses
69,978
13,378
Travelling expenses
11,470
7,630
Loss of earnings and
Loss of Housing Allowance
(after deduction of salaries tax)
8,664,999
6,125,909.5
Costs of re-education
177,974
0
Costs of care
5,810
5,810
Sub-total:
8,930,231
6,152,727.5
Sub-total (after deduction of Employees’ Compensation received):
8,381,879 (including a deduction for tax)
5,507,607

155. I award the sums of $13,378, $7,630 and $5,810 in respect of medical and therapy expenses, travelling expenses, and costs of care. The latter amount is agreed. I do not award the expenses incurred in obtaining psychiatric and psychological treatment and the travelling expenses incurred in respect of such treatments, as these claims are not supported by admissible expert evidence.

156. By far, the greatest claim under this head is in respect of past loss of earnings.

157. The plaintiff give evidence about the steps she took to find alternative employment[279]. The plaintiff retired from the civil service in August 2004. In between September 2005 and late 2008, she pursued a Masters’ course in translating and interpreting (MATI) at the Hong Kong Polytechnic University. She found herself unable to do translation work full-time, as a result of pain and discomfort in her right hand and wrist caused by computer work and hand writing.

158. She then started a part-time Master of Arts in Biblical Studies (MABS) course in September 2009. She carried on with the MABS course until mid-July 2011, without graduating, when she switched to study for a full-time Master of Divinity (MDiv) course commencing September 2011.

159. In January 2014, without graduating from the MDiv course, she switched back to the MABS course, which she completed in November 2015. She then continued with the MDiv course in January 2016, which she would have completed in November 2017.

160. I do not pay any heed to the plaintiff’s complaint that she was psychologically impaired[280] as no admissible expert evidence was adduced to support such claim. I also do not accept her claim that she was unable to perform translation work because of pain and discomfort in her right hand and wrist. In September 2009, when she had started her part time MABS course, she had been re-examined by Professor PC Leung who noted further improvement. Numbness over the right hand was only occasionally felt, and the wrist pain would only come on with strenuous wrist motion, particularly on twisting. Computer work, and handwriting, does not require strenuous wrist motion and twisting. Professor PC Leung was also of the opinion that she was no longer suffering from any CTS of the right or left wrists.[281]

161. The plaintiff pleads her claim in the Updated Amended Revised Statement of Damages as follows:

“3. Loss of Earnings
From September 1998 to January 2000, the Plaintiff worked as a Dental Officer and in addition to her basic salary, she also enjoyed pension, medical and housing allowance.
The Plaintiff was invalided from work as a dental officer with the DOH on 23 August 2004 at a monthly salary of $66,488. The present salary of a dental officer in the DOH is $99,205. The average monthly income for a dental officer between August 2004 and December 2016 is $82,847 ((66,488 + 99,205) / 2).
The Plaintiff claims the sum of $12,261,356 for loss of earnings (24 August 2004 to 24 December 2016) (82,847 x 148 months)).
The Plaintiff had to take no-pay sick leave from August to October 2002 and claims $190,864 for loss of income during this period.
Thus the Plaintiff’s loss was $12,452,220 ($12,261,356 + $190,864).
The Plaintiff will give credit for the following income:
From June 30 to September 2008, the Plaintiff worked as an Election and Expenses Agent during this employment she earned a total of $30,000.
In November 2008, the Plaintiff worked as a freelance translator and she earned a total of $1,421.
From December 2008 to February 2009, the Plaintiff worked as a medical correspondent with CMP Medica and earned in total $49,306.
From February 2009 to October 2009, the Plaintiff worked as a freelance translator earning $26,959 in total.
From October 2009 to August 2011, the Plaintiff worked as a freelance translator and a private tutor, earning in total $39,652 and $56,520 respectively.
From July to October 2014, the Plaintiff worked as a freelance translator and earned a total of $23,494. From July to August 2016, the Plaintiff worked as a summer intern and earned $4,500.
The Plaintiff’s studies and expenses have been subsidised by a church scholarship of $3,500/month from September 2011 to June 2012 and then $3,800/month from July 2012 to January 2014. From February to July 2016, the Plaintiff also received $4,000/month. She has received a total of HK$131,200.00 as her study subsidies.
The Plaintiff deducts $363,052 in total for remuneration received pre-trial. The Plaintiff also gives credit for the amount of $645,120 that she received for her Employees Compensation Award.
The Plaintiff will also deduct the sum of $2,998,496 that she received as her pension up to December 2016.
The Plaintiff will also give credit for the sum of $172,396 that she received for her full pay sick leave up to September 2000.
The Plaintiff’s pre-trial loss of earnings would be $8,273,156 ($12,452,220 – $363,052 – $645,120 – $2,998,496 – 172,396)
The Plaintiff will then deduct 15% for salaries tax. The resultant sum claimed after tax for pre-trial loss of earnings is $7,032,183.”[282]

162. The defendant’s case on pre-trial loss of earnings is as follows:

“Detailed calculations contained in pp.10-11 AUARSD[283] [A1/11/214-215], summarized as follows:
(i) Loss of basic salary during the no-pay sick leave period: $107,442.57 (§26 AARSD[284] [A1/7/128-129]);
(ii) Pre-trial loss of basic monthly earnings from Sept 2004 to Dec 2006, after deduction for notional salary tax (see Table 3 [A1/11/237] for notional tax calculations, and Table 2 [A1/11/236] for the relevant basic allowance for tax purposes): [($82,846.5 x 148 months) – $1,692,016.31] = $10,569,265.69;
(iii) Notional salary for the period from Sept 2004 to Dec 2016, after deduction for notional salary tax (see Table 4 [A1/11/238] for notional tax calculations): [($21,500 x 148) – $537,285] = $2,644,715; [Please see §§129-135 of D’s Final Submissions in relation to P’s failure to mitigate her loss.]
(iv) Total monthly pension received for the period from 23.8.04 to 31.12.16 (Table 1 [A1/11/235], after deduction for estimated tax (Table 5 [A1/11/239]): $2,993,400.16 –$126,440.83 = $2,866,959.33; and
(v) Pre-trial loss of earnings: ($107,442.57 + $10,569,265.69 – $2,644,715 – $2,866,959.33) = $5,165,034.”[285]

163. The first difference between the parties is in respect of the plaintiff’s claim for $190,864, being no-pay sick leave from August to October 2002. I accept the defendant’s evidence and calculations and assess this claim in the sum of $107,443 (rounded off) as follows:

“She was in fact on on-pay sick leave only from 8 September to 28 October 2002. Loss of income during the period is therefore calculated as follows:
• Notional basic salary in September and October 2002, had the Plaintiff not been on no-pay sick leave: $65,915 + $63,0051 = $128,920.00;
• Actual basic salary received in September 2002: $15,380.17;
• Actual basic salary received in October 2002: $6,097.26;
• Loss of basic salary during the no-pay sick leave period:
$128,920.00 – $15,380.17 – $6,097.26 = $107,442.57.
1There was a salary downward adjustment with effect from 1 October 2002.”[286]

164. The second difference between the parties is in respect of the plaintiff’s claim of $12,261,356 for loss of earnings from 24 August 2004 to 24 December 2016 (82,847 x 148 months)) less 15% salary tax. Again, I accept the defendant’s evidence and calculations and assess this claim (up to end December 2016) in the sum of $10,569,266 (rounded off) as follows:

“Pre-trial loss of basic monthly earnings from Sept 2004 to Dec 2016, after deduction for notional salary tax (see Table 3 [A1/11/237] for notional tax calculations, and Table 2 [A1/11/236] for the relevant basic allowance for tax purposes): [($82,846.5 x 148 months) – $1,692,016.31] = $10,569,265.69”

I divide the sum of $10,569,266 by 148 months to produce a monthly loss of basic earnings, net of tax, in the sum of $71,414 (rounded off) to assess the additional loss from January 2017 to March 2019 in the sum of $1,928,178, net of tax, which produces the sum of $12,497,444 ($10,569,266 + $1,928,178), being pre-trial loss of basic monthly earnings from September 2004 to March 2019. My assessment of the additional loss from January 2017 to March 2019 in the sum of $1,928,178, net of tax, is not final and can be varied in accordance with the liberty to apply I have granted in §194 below.

165. The main difference between the parties is the notional salary of $21,500 that the defendant avers the plaintiff should have been earning since September 2004. I agree with the plaintiff’s submission that she should be allowed sometime retrain herself in a different discipline and to find suitable employment in such discipline. As she had been invalidated in August 2004, she had passed the deadline in which to apply to enrol in a suitable course in her selected discipline. I also find that it was reasonable for her to take a full-time two-year course to retrain in her selected discipline. I also find that she ought reasonably to have found gainful employment in her selected discipline by September 2007 and that she ought to have earned a median salary of $21,500 from September 2007 up to March 2019 based on published statistics set out as follows:

“28. According to Population Census 2011 (Main Report: Volume 1), published by the Census and Statistics Department of the Hong Kong Government, the median monthly wage of a female degree holder in 2006 is $16,8802. According to the Report on Annual Earnings and Hours Survey published by the same Department in March 2014, the median monthly wage of a full-time employee with tertiary education was $23,000 in May-June 20133.
29. It is therefore reasonable to expect the Plaintiff to earn about $17,000 per month in August 2004, and about $24,000 per month at present. Her average monthly earning since retirement from the civil service ought therefore be about $20,500[287].
2 No figure is obtainable for the year 2004. However, due to the low inflation rate between 2004 and 2006, the corresponding figure for 2004 should be similar.
3 http://www.statistics.gov.hk/pub/B10500142013AN13B0100.pdf ”[288]

166. On the above basis, I make the following assessment and award for pre-trial loss of earnings up to March 2019, using the defendant’s evidence and calculations as follows:

Notional salary for the period from September 2004 to December 2016, after deduction for notional salary tax (see Table 4 [A1/11/238] for notional tax calculations): [($21,500 x 148) – $537,285] = $2,644,715.

I divide the sum of $2,644,715 by 148 months to produce a monthly notional salary, net of tax, in the sum of $17,870 (rounded off) to assess the notional salary from September 2007 to March 2019 in the sum of $2,483,930 ($17,870, x 139 months), net of tax.

This assessment is not final and can be varied in accordance with the liberty to apply I have granted in §194 below.

167. The plaintiff has offered to deduct the sum of $2,998,496 that she received as her pension up to December 2016. The defendant’s evidence and calculations establish that the pension to be deducted should be in the lesser amount of $2,866,959 (rounded off) calculated as follows:

Total monthly pension received for the period from 23.8.04 to 31.12.16 (Table 1 [A1/11/235], after deduction for estimated tax (Table 5 [A1/11/239]):
$2,993,400.16 –$126,440.83 = $2,866,959.33

However, I do not accept the plaintiff’s concession which is wrong in law[289]. Where loss of pre-retirement income is in issue, pension payments received from the employer before what would otherwise have been the date of retirement are not to be taken into account in assessing the plaintiff’s loss: the pension payments that the plaintiff has received were funded by contributions from her salary towards the pension fund when she was employed and the payment of pension to her represents the fruit of her contributions – these pension payments are in the same position as insurance money[290] and are not to be set off against the claim for loss of earnings[291]. I decline to deduct the pension payments that the plaintiff has received to reduce a claim for pre-trial loss of earnings.

168. My assessment of pre-trial loss of earnings from September 2004 to March 2019 is as follows:

Pre-trial loss of earnings:

($107,443 + $12,497,444 – $2,483,930) = $10,120,957

This assessment in the sum of $10,120,957 is not final and can be varied in accordance with the liberty to apply I have granted in §194 below.

169. The final claim under this head is in respect of costs of re-education in the amount of $177,974. The defendant does not dispute that, in principle, the plaintiff is entitled to claim reasonable expenses incurred for the purpose of training/education, so as to enable her to find an alternative job. However, the defendant avers that it ought not to be responsible for all the expenses she has incurred in the various courses that she had taken and then abandoned and then retaken[292]. I agree and I only allow and award the sum of $90,000 as the pre-trial cost of re-education, being about half of the amount claimed by the plaintiff.

[size=1em]Future loss and expenses

170. The differences between the parties under this head of claim are set out below:

[td]
Post-trial Loss and Expenses Plaintiff Defendant
Loss of earnings & pension 18,627,970 9,078,540.6
Medical expenses/appliance 187,390 6,310
Loss of earning capacity 142,800 142,800
Sub-total 18,958,160 9,227,650

171. I award the sum of $6,310 but do not award the rest of the expenses claimed, being expenses to be incurred in obtaining psychiatric and psychological treatment and the travelling expenses to be incurred in respect of such treatments, as these claims are not supported by admissible expert evidence.

172. The claim for loss of earning capacity is agreed in the sum of $142,800.

173. The plaintiff pleads her claim for future loss of earnings in the Updated Amended Revised Statement of Damages as follows:

“Future loss of earnings
A government Dental Officer is usually promoted to Senior Dental Officer after an average of 20.1 years satisfactory service. Applying these data, it is assumed that the Plaintiff would have been promoted to a Senior Dental in March 2017.
After promotion to a Senior Dental Officer in 1 March 2017, the Plaintiff would have received monthly salary of $121,985. Her loss of income from 1 March 2017 to 19 December 2026 would be HK$13,818,461.00
($121,985 X 12 months X 9.44 (multiplier))
The earliest date the Plaintiff can complete her MABS studies would be November 2017. The Plaintiff hopes to find employment as a pastor’s assistant with an expected monthly income of about HK$15,000.00. The anticipated earnings of the Plaintiff from 1 November 2017 to 19 December 2026 would be $1,699,200 ($15,000 x 12 months x 9.44 (multiplier)).
The Plaintiff’s future loss of earnings would be $12,119,261 ($13,818,461 – $1,699,200).
After deducting 15% for salaries tax, the Plaintiff claims the sum of $10,301,371
In the alternative, should the Plaintiff not have been promoted to Senior Dental Officer at the age of 50 in 2016, the Plaintiff would, more probably than not, have entered the private sector, earning on average around $100,000 per month. Her loss of income from 1 January 2017 to 19 December 2026 would be $11,328,000 ($100,000 X 12 months X 9.44). Similarly, after deducting 15% for salaries tax, the Plaintiff claims the sum of $9,628,000”[293]

174. The defendant’s case on future loss of earnings is as follows:

“(c) Pp. 18-19 of AUARSD [A1/11/222-223] for detailed calculations, which may be summarized as follows:
(i) Had P not retired from the civil service, her present monthly salary would have been $99,205 (MPS 44); yearly income, after deduction for tax liability (Table 7 [A1/11/241]) is therefore: ($99,205 x 12) – $167,938.20 = $1,022,521.80;
(ii) According to Census & Statistics figures, P is reasonable expected to be able to earn $26,000 per month at present (p. 10 of AUARSD [A1/11/214]); her yearly notional income, after deduction for tax liability (Table 8 [A1/11/242]), is: ($26,000 x 12) – $53,040 = $258,960;
(iii) According to a memo from the Director of Accounting Services dated 13.7.16 [F/54/208], P is receiving monthly pension of $24,972.15; her yearly pension income, after deduction for estimated tax liability (Table 8 [A1/11/243]), is: ($24,972.15 x 12) – $16,503.19 = $238,162.61[294];
(iv) P was 50 years old at the date of trial. According to Table 8 of the Personal Injury Tables Hong Kong 2016, for a female who retires at the pension age of 60, and adopting a discount rate of 1% (wrongly stated to be 1.5% in AUARDS [A1/11/223]), the appropriate multiplier ought to be 9.44;
(v) Loss under this head is therefore: [($1,022,521.80 – $258,960 – [$283,162.61[295]]) x 9.44] = $4,534,968.35.”[296]

175. The major dispute between the parties under this head of claim is the likelihood of the plaintiff being promoted to the rank of Senior Dental Officer (“SDO”) if she had not suffered the TFC injury on 30 October 1999. Although the plaintiff does not have to prove on the balance of probabilities that she would be promoted, the plaintiff must prove as a matter of causation that she has a real or substantial chance of being promoted, as opposed to a speculative one[297]. The court will look at statistical information on the proportion of workers in the particular occupation or work place who go on to obtain promotion, and when such promotion usually takes place, i.e. the average ages for promotion in the particular occupation or workplace. The plaintiff’s personnel records would need to be reviewed and the particular characteristics of the plaintiff would be taken into account in determining his or her chances of promotion and when this might have arisen.

176. In considering this issue, I have reviewed the evidence[298] and I have noted the following matters:

(a)  the plaintiff’s overall performance since she joined the Dental service was good. In terms of fitness for promotion, she was regularly assessed to be “likely to be fitted for promotion later on” between 1997 and 2001, and “to have potential to rise about one rank but probably no further”;[299]
(b)  the establishment pyramid for the dental officers’ grade was steep; while there are 248 dental officers, there are only 64 senior dental officers;
(c)  it was not uncommon for Dental Officers of the General Stream not to be promoted in their whole civil service career and there were in fact 71 Dental Officers who joined the service prior to 1 February 1997 and who never got promoted to senior rank; and
(d)  out of the 21 dental officers who were appointed at about the same time as the plaintiff in February 1997, only 1 officer had been promoted to the rank of SDO as at the year 2015.

177. I find that the plaintiff’s prospects of promotion to SDO were slim. She has failed to prove that she enjoyed a real or substantial chance of being promoted after 20 years’ service. Given the evidence that I have considered in sub-paragraphs (b) to (d) above, the fact that Dr Sunny Tsui was promoted after 12 years of service[300], that Dr Wilkie Lui was promoted after 16 years of service[301], that Dr Cham Kwong Man was promoted after this 16 years of service[302] and that Dr Yau Chuen Kam was promoted after 8 years of service[303] does not persuade me that the plaintiff enjoyed a real or substantial chance of promotion to SDO after 20 years of service.

178. The plaintiff has put forward an alternative claim on the basis that she would leave the public service and enter into private practice, if she was not promoted when she reached the age of 50. If she had not suffered the TFC injury, I am not satisfied that she would have left public service and entered into private practice even if she had not been promoted. As is apparent from the table compiled by Ms Chui Oi Yee[304], out of 21 dental officers appointed at about the same time as the plaintiff, 19 have remained in the public service. It is not known whether the remaining two have entered private service.

179. Except in respect of the deduction for pensions to be received, I accept the defendant’s submissions on how the claim for future loss of earnings ought to be assessed. Accordingly, I make the following assessment.

180. If the plaintiff had not suffered the TFC injury and had retired from the dental service, her monthly salary would have been $99,205 (MPS 44) in March 2017; and her annual income, after deduction for tax liability[305] ought to have been:

($99,205 x 12) – $167,938.20 = $1,022,522 (rounded off).

181. I find, based on Census & Statistics figures, that the plaintiff’s notional salary would have increased to $26,000 per month at present (p. 10 of AUARSD [A1/11/214]); and her annual notional income, after deduction for tax liability[306], would be:

($26,000 x 12) – $53,040 = $258,960.

182. According to the memorandum from the Director of Accounting Services dated 13 July 2016[307], the plaintiff was receiving monthly pension of $24,972.15; and I find that her annual pension income, after deduction for estimated tax liability[308], would be: ($24,972.15 x 12) – $16,503.19 = $283,163 (rounded off). The plaintiff has not made any concession about the deduction of such pension payments from her claim for future loss of earnings. For the reasons set out in §167 above, and I decline to make this deduction.

183. The plaintiff was born on 19 December 1966[309] and is now 52 years old. According to Table 8 of the Personal Injury Tables Hong Kong 2016, the appropriate multiplier, adopting a discount rate of 1%[310] for a future loss not exceeding 10 years, for a female aged 52, who would have retired at the age of 60, is 7.63.

184. Accordingly, I assess and award damages for future loss of earnings as follows: ($1,022,522 – $258,960) x 7.63 = $5,825,978.This assessment in the sum of $5,825,978 is not final and can be varied in accordance with the liberty to apply I have granted in §194 below.

185. The plaintiff pleads her claim for future loss of pension in the Updated Amended Revised Statement of Damages as follows:

“Loss of pension
Date of Trial: 12 December 2016
Highest annual pensionable emolument (Senior Dental Officer): $121,985 X 12 = $1,463,820
Length of Pensionable Service at retirement age of 60: 358.6 months
Pension factor (Category A Officer): 1/675
The formula for annual pension – “Highest annual pensionable Emoluments”x“Length of Pensionable Service (in months)” x “Pension Factor.”
The Plaintiff’s annual pension which she could have expected at age 60 without injury (121,985 x 12) x 358.6 months x 1/675 = $777,668.
The discounted pension multiplier for a female aged 50 years at trial (Table 20) is 16.45, discounted 2.5%.
The Plaintiff’s loss of pension is therefore $12,792,639 (777,668 x 16.45), less the pension of $2,996,640 (24,972 x 12 x 10) to be received between 2016 and notional retirement in 2026.
Therefore the pension loss of the Plaintiff is $9,795,999 (12,792,639 – $2,996,640).
The Plaintiff will then deduct 15% for salaries tax. Thus, for loss of pension the Plaintiff will claim after tax the sum of $8,326,599”[311]

186. The defendant’s case on future loss of pension is as follows:

“(a) §§47-51 of AARSD [A1/7/133-134] for D’s pleaded case in this respect; and
(b) P.20 of AUARSD [A1/11/224] for detailed calculations, which may be summarized as follows:
(i) Assumed salary at the time of notional retirement at the age of 60: $99,205 (the maximum present monthly salary of a Dental Officer);
[Annual pension at time of notional retirement: $99,205 x 12 x (358.6 x 1/675) = $632,442.90;][312]
(ii) Notional annual pension at the time of retirement, less tax liability (Table 10 [A1/11/244]):
$632,442.90 – $73,075.29 = $559,367.61;
(iii) The annual pension that P is receiving (Footnote 9(c)(iii) above[313]), less tax liability (Table 9 [A/11/243]), is: ($24,972.15 x 12) – $16,503.19 = $283,162.61;
(iv) According to Table 20 of the Personal Injury Tables Hong Kong 2016, for a female who is aged 50 at the date of trial, and adopting a discount rate of 2.5%, the multiplier for loss of pension commencing age 60 ought to be 16.45;
(v) Loss under this head is therefore: ($559,367.61 – $283,162.61) x 16.45 = $4,543,572.25.”[314]

187. There is no dispute regarding the plaintiff’s length of pensionable service at retirement age of 60, the pension factor of 1/675, and the formula for calculating annual pension. The pension calculator and the pension benefits formulae can be found on the Civil Service Bureau website[315].

188. An injured plaintiff who has to retire earlier than planned and is prevented from continuing to earn and to make contributions to an occupational pension, or an injured plaintiff who can continue to work but is earning less and thus unable to make a higher earning related pension contribution, may make a claim for loss of pension benefits. An award of damages for loss of pension benefits is not an award for future loss: the award is compensation for lost earnings that have been deferred to retirement age[316].

189. The court uses a multiplier/multiplicand approach to assess loss of pension benefit from the date of retirement to the date of natural death when the pension payments would have stopped. The capital sum thus obtained must be discounted for accelerated receipt, for example, a plaintiff who is aged 50 at the date of trial and who would have retired at 60, but for the accident, would need to discount the capital sum, assessed by using a multiplier/multiplicand approach, to take into account accelerated receipt of 10 years. These complex calculations, i.e. the first calculation using the multiplier/multiplicand approach to assess loss of pension benefit from the date of retirement to the date of natural death, and the second calculation of discounting, for accelerated receipt, the capital sum, obtained by using the multiplier/multiplicand approach, have been built into the Chan Tables in Tables 20 to 26[317]. Unlike the other multiplier tables, the multipliers in these tables get larger as the plaintiff’s age at trial gets closer to his retirement age. This is because the discount for accelerated receipt becomes less.

190. As I stated in §167 above, where loss of pre-retirement income is in issue, pension payments received from the employer before what would otherwise have been the date of retirement are not to be taken into account in assessing the plaintiff’s loss. However, this rule does not apply to claims for loss of post retirement pension benefits: insofar as the plaintiff is actually receiving a pension and continuing to receive a pension after his retirement date, had he not suffered the accident, to that extent, he has not lost pension benefits. In such a case, the plaintiff has not lost all the future pension, only part of it: it is a deduction of part pension against full pension, not a deduction of pension against lost earnings[318].

191. Applying these principles, I make the following assessment:

(a)  Assumed salary at the time of notional retirement at the age of 60: $99,205 (the maximum monthly salary of a Dental Officer in or about December 2016);
(b)  Annual pension at time of notional retirement:
$99,205 x 12 x (358.6 x 1/675) = $632,443 (rounded off);
(c)  Notional annual pension at the time of retirement, less tax liability[319] :  $632,443 – $73,075 (rounded off)  = $559,368;
(d)  The annual pension that the plaintiff is receiving, less tax liability[320] is:
($24,972.15 x 12) – $16,503.19 = $283,163 (rounded off);
(e)  According to Table 20 of the Personal Injury Tables Hong Kong 2016, the appropriate multiplier for loss of pension commencing age 60 for a female aged 52, adopting a discount rate of 2.5%, is 17.26.

192. In Chan Pak Ting v. Chan Chi Kuen (No.1)[321], I explained that the multiplier tables do not take account of other risks and vicissitudes of life, other than mortality, such as the possibility that the plaintiff would have ceased to earn for periods of time due to ill-health, or loss of employment, or may cease work for periods of time to care for children or other dependents[322]. The actuarial tables published by the UK Government’s Actuary Department, known as the Ogden Tables, discuss these contingencies and, in Tables A to D, provide calculations to be made of the appropriate discount for contingencies[323]. Although the validity of Tables A to D is not universally accepted, they can provide a useful starting point for the court to consider in assessing an appropriate discount in respect of contingencies other than mortality. However, I need not embark upon this exercise as the defendant has not asserted that an additional discount ought to be made on account of contingencies other than mortality[324].

193. Accordingly, I assess and award future loss of pension benefits in the sum of ($559,368 – $283,163) x 17.26 = $4,767,298. This assessment in the sum of $4,767,298 is not final and can be varied in accordance with the liberty to apply I have granted in §194 below.

[size=1em]Liberty to apply

194. I grant liberty to the parties to apply to vary my awards for pre-trial and future loss of earnings and loss of pension benefits, net of tax, on account of the rise in salary of a dental officer, and the tax on such increased salary and pension benefits, and of the plaintiff’s notional salary from January 2017 to March 2019, and the tax on such increased salary and pension benefits.

[size=1em]Deduction of employees’ compensation

195. There is no tax payable on the award of employees’ compensation and the plaintiff’s deduction of 15% on account of tax is erroneous[325]. The full award of employees’ compensation in the sum of $645,120 must be deducted.

[size=1em]Interest

196. The usual order for interest that is made on judgments for damages for personal injuries is as follows:

(a) interest is awarded at the rate of 2% per annum on general damages for PSLA, including damages for loss of congenial employment, from the date of service of the writ up to the date of judgment; and
(b) interest is awarded at half the judgment rate on pre-trial special damages, including pre-trial loss of earnings, from the date of the accident up to the date of payment of employees’ compensation and, thereafter, on the remaining balance of the special damages and pre-trial loss of earnings, after deducting the amount of employees’ compensation therefrom, up to the date of judgment. The judgment rate stands at 8.125% per annum with effect from 1 April 2019, and half of that rate is 4.0625% per annum

As the loss has not yet been incurred, interest is not awarded on damages for future loss or expenses. Interest is also not awarded on damages for loss of earning capacity which is an award of damages in respect of future loss. These awards are advance payments for future loss.

197. The unusual feature about this case is that it was started in 2002, the writ having been issued on 25 September 2002. The trial only commenced on 12 December 2016, more than 14 years later. The defendant asserts that I should disallow interest for those periods of time when the plaintiff was guilty of delay.

198. The principles governing the award of interest are clear. It is provided in section 48 (1) and (2) of the High Court Ordinance, Cap. 4, that, in relation to a judgment given for damages for personal injuries or death, there shall be included in any sum for which judgment is given simple interest, at such rate and for such period, as the court thinks fit, on any part of the damages awarded, unless the court is satisfied that there are special reasons to the contrary. The onus is on the defendant to establish special reasons to deny the award of interest. Watkins LJ explained the rationale for denying interest in Birkett v Hayes[326]:

“It is … wrong that interest should run during a time which can properly be called unjustifiable delay after the date of the writ. During that time the plaintiff will have been kept out of the sum awarded to him by his own fault. The fact that the defendants have had the use of the sum during that time is no good reason for excusing that fault and allowing interest to run during that time.”

As long ago as 1970, Lord Denning said in Jefford v. Gee[327]:

“In exceptional cases, such as when one party or the other has been guilty of gross delay, the court may depart from the guidelines by diminishing… The rate of interest, altering the periods for which it is allowed.”

Morland J in Read v Harries denied interest for 3 years out of the 7 year pre-trial period and said[328]:

“…the general principle is that a successful claimant is entitled to reasonable interest on the damages that I recovered by her. But in exceptional circumstances, that interest is not recoverable in full of it is established that there has been grass and unjustifiable delay either on the part of the claimant or on the part of those advising her, in prosecuting the claim and bringing the action to trial.”

199. In Spittle v. Binney[329] the Court of Appeal held that the trial judge was right to reduce his award of interest by 2 years, on account of unreasonable delay, in that case which took 7 ½ years to come to trial. Other English cases[330] in which interest has been denied for certain periods of time or where the interest rate has been reduced include Socimer International Bank Ltd v. Standard Bank London Ltd[331], Nash v. Southmead HA[332], Fairhurst v. St Helens HA[333], Eagle v. Chambers[334] and Adcock v. Co-Operative Insurance[335].

200. Hong Kong cases[336] in which interest has been denied for certain periods of time or where the interest rate has been reduced include Wong Suk ha v. Li Tsun Wing[337], Ng Yat Ying (an infant) v. Law Ming Kwan[338]and Lo Yuk Sui v. Fubon Bank (Hong Kong ) Ltd. & Anor[339].

201. I agree with the editors of Kemp & Kemp that “the court will take a broad brush approach in reducing interest where there is delay by a claimant”[340] Indeed, Ng J. adopted a broad brush approach in Lo Yuk Sui v. Fubon Bank (Hong Kong ) Ltd. & Anor[341].

202. I have considered the parties’ respective submissions, written and oral, on the exercise of my discretion to allow disallow interest[342]. In the defendant’s Summary of Quantum Assessment dated 10 March 2017, the defendant did not advance any new submissions and only reiterated its submissions in §§24-26 and 51-58 of the defendant’s reply submissions. The plaintiff’s response dated 17 March 2017 to the defendant’s Summary of Quantum Assessment contained 51 paragraphs of written submissions on the issue of interest[343] and went outside the ambit of the leave I had granted to the plaintiff[344]. I disregard these additional written submissions.

203. It appears from the Court file that the action was dormant from 10 November 2003 to 7 September 2011:

[td]
Folio
Filing Date
Document name
1 25/09/2002 Writ of Summons
2 07/05/2003 Medical Report
3 07/05/2003 Statement of Damages
4 07/05/2003 Statement of Claim
5 12/05/2003 Acknowledgement of Service [Y D1]
6 03/07/2003 Defence [D1]
7 01/09/2003 Reply
8 20/09/2003 List of Documents of Defendant(s)
9 09/10/2003 Order (dated) 22.9.2003
10 31/05/2007 Notice of Change of Solicitors
11 09/01/2008 Notice of Intention to Proceed
12 19/02/2008 List of Documents of Plaintiff(s)
13 02/10/2008 Memorandum of Notification of an Application of Legal Aid
14 15/12/2008 Memorandum of Notification that a Party has been refused Aid
15 05/01/2009 Memorandum of Notification of an Application of Legal Aid
16 18/03/2009 Memorandum of Notification that a Party has been refused Aid
17 07/05/2009 Affidavit/Affirmation of Cheng Mung Shuen Annie with exhibit (a-f)
18 07/05/2009 Summons (Hearing dated: 27/05/2009 09:30 Chambers List
(To cease acting)
19 11/05/2009 Affidavit/Affirmation of Tsang Wing Pui with exhibit a
20 04/06/2009 Order dated 27.05.2009
21 11/06/2009 Certificate of Service
22 08/02/2010 LA Memorandum Of Notification That A Party Has Applied for Legal Aid
23 23/04/2010 LA Notice Of Issue Of Legal Aid Certificate
24 05/05/2010 Notice to Act
25 29/06/2010 Notice of Intention to Proceed
26 12/08/2010 LA Notice Of Assignment Of Solicitors/Counsel
27 07/09/2011 Notice of Intention to Proceed

The order made on 22 September 2003 was an order made at a Check List Review directing that witness statements be exchanged and giving further directions for the conduct of the action. A Check List Review was also fixed to be heard on 10 November 2003. Pursuant to the order of 22 September 2003, the plaintiff served, albeit late, her written statement dated 13 December 2003[345]. The steps taken in May and June 2009 were in relation to the plaintiff’s solicitors application to cease to act which was granted.

204. It appears from the Court’s correspondence file that the Check ListReview heard on 10 November 2003 was adjourned to 20 February 2004. The latter date was vacated later and the Check List Review was refixed to be heard on 23 April 2004. However, on 30 March 2004, the Check List Review, fixed to be heard on 23 April 2004, was again vacated and the parties were asked to send representatives to fix the adjourned Check List Review. This was never done. The next Check List Review was fixed many years later on 17 February 2012.

205. The steps taken by the parties between 9 October 2003 to 7 September 2011 are detailed in the defendant’s “Chronology of Major Events of Delay”[346] which I have reviewed and rely upon. It has not been suggested that the chronology is inaccurate. I have also had regard to the plaintiff’s chronology that was handed up to me in the course of final submissions on 2 March 2017[347].

206. After having regard to the court file, the court’s correspondence file and the parties’ chronologies, I conclude that there has been substantial inactivity in the prosecution of this action from 2005 at least until September 2011 when the plaintiff took steps to obtain expert evidence[348]. In the course of final submissions on 2 March 2017 I remarked:

“COURT: Isn’t this a special reason, Mr Barretto? Since the implementation of the CJR, that goes back now some seven years, we are very proud in Hong Kong to note that 75 per cent of all personal injury cases that are started in the High Court are resolved and concluded within 18 months from the date of service of the writ -- from the date of issue of the writ. This case was started in 2002 and it’s now 2017. That is a stark, stark exception and a very special reason as far as I’m concerned.”[349]

207. Was such a delay justified? The plaintiff puts forward the following reasons to try to explain the very substantial delay:

(a)  failure on the part of the defendant to disclose documents;
(b)  the plaintiff’s psychiatric disability; and
(c)  lack of funds which prevented progress.

208. The plaintiff cannot rely upon the defendant’s delay or refusal to disclose documents as an excuse for her very substantial delay in prosecuting this action. She was under a duty to pursue her action speedily and diligently. Even if the defendant had unreasonably refused to provide the requested documents, it was the plaintiff’s duty to seek the court’s assistance by way of suitable applications for discovery. The plaintiff could not simply wait and do nothing.

209. In the absence of admissible expert evidence in support, I am unable to rely on any psychiatric or psychological impediment the plaintiff may wish to rely upon to excuse her failure to prosecute the action diligently. The plaintiff was certainly able to give detailed and cogent instructions which enabled her 1st witness statement dated 13 December 2003 to be made and served.

210. The plaintiff’s lack of funds, difficulties in instructing solicitors to represent her, and the fact that she was not eligible to qualify for legal aid until January 2009 do not constitute sufficient reason to justify the very substantial delay in prosecuting the action from 2005 to August 2011.

211. I am satisfied that special reasons have been established for me to depart from requirement in section 48 (1) and (2) of the High Court Ordinance to award interest for the full pre-trial period in this case. In the exercise of my discretion, I award interest as follows:

(a) interest is awarded at the rate of 2% per annum on general damages for PSLA, including damages for loss of congenial employment, from the date of service of the writ up to 31 December 2004 and from 1 September 2011 to the date of judgment;
(b) interest is awarded at 4.0625% on pre-trial special damages, including pre-trial loss of earnings, from the date of the accident up to the date of payment of employees’ compensation on 30 July 2004 and, thereafter, on the remaining balance of the special damages and pre-trial loss of earnings, after deducting the amount of employees’ compensation therefrom, from 31 July 2004 to 31 December 2004 and, thereafter, on the said remaining balance from 1 September 2011 up to the date of judgment.

[size=1em]My award

212. A summary of my award is set out below:

General Damages $
PSLA 325,000
Loss of congenial employment 150,000
Sub-total: 475,000
Pre-trial Loss and Expenses
Medical & Therapy expenses 13,378
Travelling expenses 7,630
Loss of earnings (after deduction of salaries tax) 10,120,957
Costs of re-education 90,000
Costs of care 5,810
Sub-total: 10,237,775
Sub-total (after deduction of Employees’ Compensation received in the sum of $645,000 on30 July 2004[350]): 9,592,775
Post-trial Loss and Expenses
Loss of earnings 5,825,978
Loss of pension 4,767,298
Medical expenses/appliances 6,310
Loss of earning capacity 142,800
Sub-total 10,742,386
And Interest as awarded above on:
General damages To be calculated
Pre-trial pecuniary losses To be calculated
Sub-total To be calculated
Total Damages To be calculated

213. I award damages to the plaintiff in the total sum of $20,810,161 ($475,000 + $9,592,775 + $10,742,386) and interest to be calculated. This award is not final and can be varied in accordance with the liberty to apply I have granted in §194 above.

214. I make a costs order nisi that the defendant pays the plaintiff’s to be taxed, if not agreed, and that the plaintiff’s own costs be taxed pursuant to the Legal Aid Regulations.

215. I cannot conclude this judgment without expressing my gratitude to counsel for the assistance I received.

	(Mohan Bharwaney)
	Judge of the Court of First Instance
	High Court

Mr Ruy Barretto SC and Mr Douglas Jones, instructed by Ho, Tse, Wai & Partners, assigned by Director of Legal Aid, for the plaintiff

Mr Simon K C Lam, instructed by Department of Justice, for the defendant

APPENDIX

APPENDIX A – A USER’S GUIDE FOR THE STRAIN INDEX

This guide describes how to perform the five steps associated with using the Strain Index. Page 1 describes the rating criteria and the measurements and calculations for the six task variables. The numerical ranges for assigning rating criteria for the subjective variables are only guidelines. Page 2 includes a table for entering your data and guides you through calculating an SI score.

Step 1: Data Collection

1. Intensity of Exertion is an estimate of the strength required to perform the task one time. Guidelines for assigning a rating criterion are presented in the following table. Write the most appropriate rating criterion into the data table.

Rating Criterion	%MSA	Borg ScaleB	Perceived Effort
_________________________________________________________________________________________
Light	<10%	<2	barely noticeable or relaxed effort
Somewhat Hard	10%–29%	3	noticeable or definite effort
Hard	30%–49%	4–5	obvious effort; unchanged facial expression
Very Hard	50%–79%	6–7	Substantial effort; changes facial expression
Near Maximal	>80˚	>7	uses shoulder or trunk to generate force
__________________________________________________________________________________________

A Percentage of maximal strength

B Compared to the Borg CR-10 scale

2. During of Exertion is calculated by measuring the duration of all exertions during an observation period, then dividing the measured duration of exertion by the total observation time and multiplying by 100.

% Duration of Exertion = 100 x	duration of all exertions (sec)	= 100 x _______ = ________
	total observation time (sec)

3. Efforts per Minute are measured by counting the number of exertions that occur during an observation period, then dividing the number of exertions by the duration of the observation period, measured in minutes.

Efforts per Minute	=	number of exertions	=	__________	=	___________
		total observation time (min)

4. Hand/Wrist Posture is an estimate of the position of the hand or wrist relative to neutral position. Guidelines for assigning a rating criterion are presented in the following table. Enter the result in the data table.

Rating Criterion	Wrist Extension^	Wrist Flexion^	Ulnar Deviation^	Perceived Posture
_______________________________________________________________________________________
Very Good	0˚–10˚	0˚–5˚	0˚–10˚	perfectly neutral
Very Good	0˚–10˚	0˚–5˚	0˚–10˚	perfectly neutral
Good	11˚–25˚	6˚–15˚	11˚–15˚	near neutral
Fair	26˚–40˚	16˚–30˚	16˚–20˚	nonneutral
Bad	41˚–55˚	31˚–50˚	21˚–25˚	marked deviation
Very Bad	>60˚	>50˚	>25˚	near extreme
________________________________________________________________________________________

^ Derived from data presented in Stetson et al.

5. Speed of Work is an estimate of how fast the worker is working. Guidelines for assigning a rating criterion are presented in the following table. Enter the result in the data table.

Rating Criterion	Compared to MTM-1^	Perceived Posture
___________________________________________________________________________________
Very Slow	<80%	extremely relaxed pace
Slow	81–90%	“taking one’s own time”
Fair	91–100%	“normal” speed of motion
Fast	101–115%	rushed, but able to keep up
Very Fast	>115%	rushed and barely or unable to keep up
____________________________________________________________________________________

^ The observed pace is divided by MTM-1’s predicted pace and expressed as a percentage of predicted. See Barnes.

6. Duration of Task per Day is either measured or obtained from plant personnel. Enter the result in the data table.

Step 2: Assign Ratings Values

Use the table below [the] find the rating values for each task variable. Select the appropriate entry for each variable, then find the corresponding rating value on the same row at the far left.

Rating Values	Intensity of Exertion	Duration of Exertion	Efforts/Minute	Hand/Wrist Posture	Speed of Work	Duration per Day
_______________________________________________________________________________________
1	light	<10	<4	very good	very slow	<1
2	somewhat hard	10–29	4–8	good	slow	1–2
3	hard	30–49	9–14	fair	fair	2–4
4	very hard	50–79	15–19	bad	fast	4–8
5	near maximal	>80	>20	very bad	very fast	>8
_______________________________________________________________________________________

Step 3: Determine the Multipliers

Rating Values	Intensity of Exertion	Duration of Exertion	Efforts/Minute	Hand/Wrist Posture	Speed of Work	Duration per Day
____________________________________________________________________________________
1	1	0.5	0.5	1.0	1.0	0.25
2	3	1.0	1.0	1.0	1.0	0.50
3	6	1.5	1.5	1.5	1.0	0.75
4	9	2.0	2.0	2.0	1.5	1.00
5	13	3.0^	3.0^	3.0	2.0	1.50
_____________________________________________________________________________________

^ If duration of exertion is 100%, then efforts/minute multiplier should be set to 3.0.

Enter Your Data Here:

	Intensity of Exertion	Duration of Exertion	Efforts/Minute	Hand/Wrist Posture	Speed of Work	Duration per Day
_____________________________________________________________________________________
Step 1: Rating Criterion or Measured Result
_____________________________________________________________________________________
Step 2: Rating Value
_____________________________________________________________________________________
Step 3: Multiplier
______________________________________________________________________________________

Step 4: Calculate the SI Score

Insert the multiplier values for each of the six task variables into the spaces below, then multiply them all together.

Intensity of Exertion

x

Duration of Exertion

x

Efforts per Minute

x

Hand/Wrist Posture

x

Speed of Work

x

Duration of Task

=

SI Score

x

=

______________

____________

_____________

____________

_____________

____________

Step 5: Interpret the Result

Preliminary testing has revealed that jobs associated with distal upper extremity disorders had SI Scores greater than 5. SI Scores less than or equal to 3 are probably safe. SI Scores greater than or equal to 7 are probably hazardous. The Strain Index does not consider stresses related to localized mechanical compression. This risk factor should be considered separately.

[1] [T/Day1/91-Day2/86] “T” is a reference to the Transcript Bundle. [B/1-37, 38-80, 203-220] “B” is a reference to the Witness Statements Bundle.

[2] [T/Day3/1-35] [B/81-85, 221-228]

[3] [T/Day3/51-107] [B/98-108]

[4] [T/Day4/6-26] [B/91-97]

[5] [T/Day4/28-38] [B/229-258]

[6] [T/Day4/38-50] [B/132-135]

[7] [T/Day4/50-97] B/171-181]

[8] [T/Day5/1-15] [B/136-170]

[9] [T/Day4/97-105] [B/182-202]

[10] [T/Day4/105-110] [B/119-123]

[11] [T/Day5/33-Day6/95] [C/134-159G (“TJ-1”), 192, 192A-192L (“TJ-2”), 208-223 (“TJ-3”), 224-253 (“TJ-4”), 286-299 (“TJ-5”)] “C” is a reference to the Experts’ Reports Bundle.

[12] [T/Day6/95-Day7/121] [C/160-191 (“CC-1”), 192, 193-207 (“CC-2”), 254-273 (“CC-3”), 274-285 (“CC-4”)] “CC-5” and CC-6” were prepared to assist the parties and the court to understand the changes that were made by Professor Chan to his earlier reports [T/Day7/39(16)-(17)]: Defendant’s Bundle/Tab2/combined version of CC-1, CC-2 and CC-4 with tracked changes (“CC-5”) and Defendant’s Bundle /Tab 4/combined clean version of CC-1, CC-2 and CC-4 (“CC-6”), as explained in the letter from the defendant’s solicitors dated 16 December 2016.

[13] [C/1-6, 7-13, 14-20, 300-303]

[14] [C/21-35, 36-39]

[15] [C/40-53, 304-317]

[16] Bundles D, E, F, G, H, J, K, L, N, P1, P2, Q, R and Defendant’s Bundle

[17] [T/Day3/81(17)-(24), 82(21)-83(5)]

[18] See §13 of defendant’s (“D’s”) Opening Submissions

[19] [B/39-43]

[20] See §§12 - 15 below.

[21] [T/Day2/82(1)-83(12)]

[22] [E/1-16]

[23] [B/234 §17] [T/Day3/101(10)-(13), 103(10)-(13), 105(21)-107(4)]

[24] [E/9]

[25] [T/Day1/113(8)][Day2/81(1)-(12)]

[26] [T/Day1/99(5)-100(1)]

[27] [T/Day1/100(19)-102(23)]

[28] [T/Day2/18(1)-(6), 19(11)-(23)]

[29] [T/Day1/104(24)-105(18), 107(14), 110(8)]

[30] [T/Day1/100(13), 111(1)-(5)]

[31] [T/Day1/115(8)-(25)]

[32] See §26 below.

[33] [B/105 §21]

[34] One unit is 10 minutes: [T/Day3/17(23)-(24)]

[35] [E/6]

[36] [B/5 §§17-18]

[37] [B/208 §§23-24] [T/Day2/7(11)-8(25), 11(21)-(25), 14(20)-(22)] [B/82 §6, 222 §4] [T/Day3/29(17)- 32(10)] [B/133 §5] [T/Day4/42(7)-43(1), 48(12)-49(18)]

[38] [F/256]

[39] [F/257]

[40] [F/252]

[41] [B/100-101 §§6-8]

[42] [T/Day1/113(22)-(23)] [T/Day3/93(7)-(13)] [B/144: from September 1998 to January 2000, Dr Sunny Tsui had 2,049 consultations while the plaintiff had 331 consultations]

[43] [T/Day1/143(10)-(20)]

[44] [B/203, 211]

[45] [B/218 at §3(c)]

[46] [T/Day1/118-138]

[47] [B/229-258] [T/Day4/28 – 38]

[48] [B/136, 144-146]

[49] [T/Day5/1-15] [B/136-170]

[50] Appendix A at B/144 [B/140 §12]

[51] Appendix B at B/145-146 [B/140-141 §13]

[52] [T/Day5/3(7)-5(7)]

[53] [T/Day5/8(20)-9(7)]

[54] [T/Day5/9(12)-(23)]

[55] [B/146A]

[56] [B/137 §4]

[57] [B/144] [T/Day3/96(1)-(23)] One can see from the data set out in B/144 that §16 of Dr Sunny Tsui’s witness statement, in B/103, that he performed 80% of all referrals while the plaintiff performed 20% of all referrals, is incorrect.

[58] [B/81-84] [T/Day3/3(5)-(8), 4(22)-5(4), 25(21)-26(25), 27(9)-28(5)]

[59] [T/Day3/104(2)-105(14)]

[60] [B/7 §28] [T/Day1/143(20)] [Day2/23(2)-(8), 25(8)-(25)]

[61] An abnormal sensation such as tingling or numbness.

[62] [B/106 §26] [T/Day3/79(10)-(14)]

[63] [D/28]

[64] [T/Day3/86(16)-87(15)]

[65] [T/Day3/88(15)]

[66] [B/9 §§37-38), /10 Table 3 /11 §41 /12-13 Table 4 /14 Table 5]

[67] [B/9 §38]

[68] [B/106 §26]

[69] [T/Day3/91(1)-(15)]

[70] [T/Day3/92(3)-(5)] [K/1A]

[71] [B/20 §54] [B/206 §15] [T/Day2/24(1)-(20)]

[72] [T/Day2/26(5)-(7)]

[73] [B/91-97] [T/Day4/6(25)-7(10), 8(16)-(20), 10(9)-11(2), 15(7)-(16), 18(10)-(14), 19(5)-(25)]

[74] [B/203 §16]

[75] 1 SX on 27 October 1999 was later cancelled.

[76] [J/59]

[77] [T/Day2/34(3)-(10)]

[78] [T/Day2/37(24)]

[79] [T/Day2/49(1)-51(11)]

[80] [B/206-207 §§16 -18]

[81] [T/Day2/83(21)-84(3)]

[82] [B/171-181]

[83] [T/Day4/90(14)-92(12), 94(18)-95(14)]

[84] [C/1-6, 7-13, 14-20, 300-303]

[85] [C/21-35, 36-39]

[86] [C/40-53, 304-317]

[87] [C/42-44]

[88] [C/29 at §6.5]

[89] [C/44 at §3.2]

[90] [C/44 at §3.3.1]

[91] [C/44-45 at §3.3.2] [C/5 last paragraph]

[92] [C/45 at §3.3.3]

[93] [C/45 at §3.4]

[94] [C/302 last paragraph]

[95] [C/304-308]

[96] [C/304 at §2.1]

[97] [C/305 at §2.1]

[98] [C/305 at §2.2]

[99] [C/306-7 at §§3.4-3.6]

[100] [C/31 at §7.4]

[101] [C/306 at §2.4]

[102] [C/307 at §4.1]

[103] See §28 above.

[104] See §37 above.

[105] Bonnington Castings Ltd v. Wardlaw [1956] A.C. 613; Bailey v. Ministry of Defence [2009] 1 W.L.R. 1052; Williams v. Bermuda Hospitals Board [2016] A.C. 888;Clerk & Lindsell on Torts, 22nd Ed., at 2-32 to 2-34.

[106] [1939] 1 KB 394 at 400-401

[107] See the Table under §27 above. NDH was closed because of a typhoon on 16 September 1999 and 25 September 1999 was a public holiday.

[108] Hughes v. Lord Advocate [1963] AC 837

[109] [T/Day2/33(19)-48(2)] [J/59]

[110] [T/Day2/35(19)-(23)]

[111] [T/Day2/36(2)-(16)] [J/59]

[112] [T/Day2/43(9)-(10), 44(12)-(13), 46(20)-(22)]

[113] [T/Day2/49(3)-51(11)]

[114] [T/Day4/61(4)-62(4)]

[115] D’s Closing Submissions 27 §104

[116] Plaintiff’s (“P’s”) Speaking Note dated 1 March 2017 §10, Transcript of Closing Submissions at T/Day8/25A

[117] [A1/168-169 §17A]

[118] [B/19 §53]

[119] [T/Day5/33-Day6/95] [C/134-159G (“TJ-1”), 192, 192A-192L (“TJ-2”), 208-223 (“TJ-3”), 224-253 (“TJ-4”), 286-299 (“TJ-5”)]

[120] [T/Day6/95-Day7/121] [C/160-191 (“CC-1”), 192, 193-207 (“CC-2”), 254-273 (“CC-3”), 274-285 (“CC-4”)] [Defendant’s Bundle/Tab2/combined version of CC-1, CC-2 and CC-4 with tracked changes (“CC-5”) Defendant’s Bundle/Tab 4/combined clean version of CC-1, CC-2 and CC-4 (“CC-6”), as explained in the letter from the defendant’s solicitors dated 16 December 2016]

[121] Her curriculum vitae can be seen in C/159A-159C.

[122] [P1/255]

[123] Ms James reviewed the research papers on the development of musculoskeletal disorders among dental professionals in §§13-18 of TJ1 at C/138-140.

[124] [T/Day5/35(25)-37(25)]

[125] [T/Day6/96(8)-(25)] His curriculum vitae can be seen in C/191-A to 191-K.

[126] [T/Day6/111(13)-(19)]

[127] [P1/259]

[128] [P1/270] [D’s Final Submissions on 8 February 2017 at p.4 §12]

[129] [C/192] [T/Day7/64(17)-65(12)]

[130] Professor Chan

[131] In respect of the assessment by Professor Chan, only the score for SX for the entire workday is quoted. His separate scores for SX and non-surgical extractions can be found under §32 of CC-6 [Defendant’s Bundle//Tab 4/combined clean version of CC-1, CC-2 and CC-4, as explained in the letter from the defendant’s solicitors dated 16 December 2016]

[132] Ms James

[133] In respect of the assessment of Ms. James, only the score for SX is quoted. Her score for non-surgical extraction can be found under §21 of TJ1 [C/142].

[134] [P1/260] [T/Day5/52(11)-(25), T/Day6/115(22)-(23)]

[135] Tab 6 of P’s Opening Bundle.

[136] [P1/265-266]

[137] [P2/567]

[138] [P2/549-552]

[139] [Q/Tab 56]

[140] [Q/Tab 57]

[141] D’s Closing Submissions at §§20-21

[142] [T/Day7/99(20)-101(6)]

[143] P’s Closing Submissions at §142

[144] [P2/536-538]

[145] Tab 6 of P’s Opening Bundle at pp.2-3.

[146] [T/Day5/80(25)-89(25)]

[147] [T/Day5/90(15)-91(3)]

[148] [CC-5 at p.5 Defendant’s Bundle/Tab2/combined version of CC-1, CC-2 and CC-4 with tracked changes]

[149] [T/Day5/96(15)-98(10)]

[150] [T/Day5/102(24)-103(4)]

[151] [T/Day5/107(5)-(7), 110(5)-(7))]

[152] [T/Day5/111(11)-(19), 112(20)-113(13), 114(12)-115(3)]

[153] [T/Day5/121(3)-(11)]

[154] [T/Day5/122(9)-(14)]

[155] [T/Day7/28(2)-(11)]

[156] [P2/536-538]

[157] [P2/536]

[158] [T/Day7/93(10)-96(16)]

[159] The Strain Index at p.261

[160] [Q/Tab 56]

[161] At Q/Tab 56 pp.632, 635-636.

[162] At Q/Tab 56 pp.631, 638.

[163] At P2/553.

[164] [P2/536-538]

[165] [Q/Tab 56]

[166] [T/Day7/67(12)-(14)]

[167] [P2/552]

[168] [T/Day5/94(12)-(18)]

[169] Tab 6 of P’s Opening Bundle at pp.3-6.

[170] Ms James

[171] Professor Chan

[172] [C/140-143]

[173] [C/157]

[174] [T/Day6/21(11)-23(4)]

[175] P’s Closing Submissions §§82-88

[176] D’s Closing Submissions §§24-48

[177] [T/Day5/50(4)-(14), 126(20)-129(16)]

[178] [C/16/237A-AF]

[179] [T/Day5/132(5)-(9)]

[180] [T/Day5/65(4)-(24)]

[181] §21 above

[182] See §25 above.

[183] [T/Day5133(4), 140(13)-(20)]

[184] TJ-5 at C/289-290

[185] [T/Day5/144(10)-(15)]

[186] [T/Day5/144(16)-(20)]

[187] [T/Day5/48(20)-49(21)

[188] [The Strain Index at P/260] [T/Day5/135(8)-138(9), T/Day6/75(14)-76(2), 10(11)-(24)]

[189] [C/292§4(b)]

[190] [B/5§21]

[191] [T/Day6/5(1)-6(4), 6(22)-7(17), 8(8)- 9(9), 10(8)-(24), 12(6)-(10)]

[192] [T/Day6/12(6)-(11)]

[193] Extract from Reviews of Human Factors and Ergonomics, Garg and Kapellusch, 2011, at P2/553

[194] [C/287]

[195] [C/134]

[196] [C/157]

[197] [T/Day6/35(10)-40(7)]

[198] [C/287] [T/Day6/15(19)-16(2)]

[199] [T/Day6/37(8)-(10)]

[200] [P2/536]

[201] [T/Day6/26(5)-35(9)]

[202] CC-6 p.13

[203] As is clear from Ms James’ worksheet at C/157, the multiplier for Duration of Exertion is 2 when the percentage ranges from 50-79%. Ms James correctly assessed a multiplier of 2 in her worksheet. The multiplier of 3 appearing on the table in P’s Opening Tab 5, p.6 is a typographical error. The table interposed the multiplier for Duration of Exertion, which was 2, with the multiplier for Efforts per Minute, which was 3.

[204] This is a typographical error. See the preceding footnote. Ms James’ calculation in C/157 is correct: 6 times 2 times 3 times 2 times 1 times 0.75 = 54.

[205] [T/Day6/87(2)-88(8)]

[206] [C/157]

[207] [T/Day5/67(2)-(7)]

[208] Joint Note on Areas of Disagreement of the Parties’ Ergonomic Experts: Tab 6 of P’s Opening Bundle at p8.

[209] D’s Closing Submissions §§56-71

[210] P’s Reply Submissions at p.10-12 §34

[211] [C/157]

[212] There was an error on the table in P’s Opening Tab 5, p.6 which interposed the multiplier for Duration of Exertion, which was 2, with the multiplier for Efforts per Minute, which was 3.

[213] 36 is the correct Strain Index Score.

[214] [T/Day6/83(12)-85(19)]

[215] Joint Note on Areas of Disagreement of the Parties’ Ergonomic Experts: Tab 6 of P’s Opening Bundle at pp.8-9.

[216] P’s Closing Submissions p.33

[217] P’s Reply Submissions p.12

[218] D’s Closing Submissions at p.20

[219] [T/Day5/97(4)-(23)] [T/Day6/74(13)-76(180)

[220] See §66 above.

[221] [C/269-270]

[222] D’s Closing Submissions at p.21

[223] See §§28 and 39 above.

[224] [C/306-7 at §§3.4-3.6]

[225] [B/144] [T/Day3/96(1)-(23)]

[226] [B/203, 211]

[227] [B/218 at §3(c)]

[228] See §19 above.

[229] [T/Day5/1-15] [B/136-170]

[230] Appendix A at B/144 [B/140 §12]

[231] Appendix B at B/145-146 [B/140-141 §13]

[232] At p.23

[233] §21 of TJ1 [C/142]

[234] National Institute for Occupational Safety and Health: P1/271

[235] [P1/283, 284]

[236] [T/Day4/89(4)-90(8)]

[237] P’s Closing Submissions at pp.10-11

[238] [C/137]

[239] [T/Day5/75(13)-(19)]

[240] [C/45 §3.5.1].

[241] [2000] 3 HKLRD 198

[242] HCPI 776/2007, 17 September 2009

[243] HCPI 93/2002, 31 October 2002

[244] DCPI 629/2006, HH Judge Leung, 6 July 2007

[245] HCPI 281/2009, 29 March 2011

[246] HCPI 646/2012, 7 July 2017

[247] See the table on p. 65 in Personal Injury Tables Hong Kong 2016 which contains a revision of the level of PSLA awards taking into account the impact of inflation and deflation since 1996.

[248] [A/177]

[249] [A/208, 211, 225]

[250] At p.35, §128.

[251] Darts Recording on 2 September 2016 at 10:57:57 am.

[252] [D/23]

[253] HCPI 833/2002, 15 September 2014 [2014] 5 HKLRD 525

[254] HCPI 1113/2006, 24 June 2011

[255] Report of Dr Simon Siu dated December 2010: D/23-26.

[256] [B55]

[257] HCPI 43/2006, 16 March 2007

[258] HCPI 1113/2006, 24 June 2011

[259] [2012] 1 HKLRD 1 HCPI 204/2009 7 October 2011

[260] HCPI 539/2011, 6 February 2012

[261] HCPI 527/2011 13 July 2012

[262] HCPI 574/2014, 4September 2015

[263] The same quotation appears in §140 above.

[264] It was noted in the joint occupational therapist report that “she was treated by a psychiatrist who was her friend and who did not charge her much”: C/112.

[265] [C/54, 62, 69, 82, 83, 92, 93, 95, 110, 112]

[266] [C/82, 83, 92]

[267] Chan Yiu Ping v Mok Yuk Kwong & Ors HCPI 92/1998, Suffiad J, 3 July 2000

[268] [B/36 §101, 58 §46]

[269] See §§31-38, 124-132 above.

[270] The crumbling skull principle: see §42 above.

[271] [1998] 2 HKLRD 958 at p. CACV 58/1997 11 November 1997

[272] HCPI 62/2010, 11 May 2011

[273] [T/Day8/56E-G]

[274] [B/45-46 §14]

[275] [B/147 – 169] [T/Day5/2(8)-3(6)]

[276] [B/154-155] [T/Day8/58O-T]

[277] [B/167-169]

[278] Less the 2 years spent pursuing her Master’s degree.

[279] [B/33-35 §§89-91, B/47-50 §§18-26] [T/Day2/61(6)-73(5)]

[280] [T/Day2/65(16) 72(16-70)]

[281] See §§129 and 131 above.

[282] [A1/183-185]

[283] Answer to Updated Amended Revised Statement of Damages

[284] Answer to Amended Revised Statement of Damages

[285] Defendant’s Summary of Quantum dated 10 March 2017 at p.1. I have deleted the 75% discount on account of pre-existing vulnerability that is contained in the defendant's calculations.

[286] [A1/129]

[287] Further revised to $21,500: A1/238.

[288] [A1/129-130]

[289] Cf. Hollywood Shopping Centre Owners Committee Ltd. v. The Incorporated Owners of Wing Wah Building Mongkok Kowloon CACV 185/2010, 4 August 2011,at §32: the Court of Appeal permitted a concession made by a party at trial to be withdrawn as it concerned a question of law.

[290] Where the plaintiff can be shown to have paid or contributed to the cost of insurance against accidental personal injury and consequential loss, the benefit of such insurance is not deducted from the compensation award for the same injury and loss: Hussain v. New Taplow Paper Mills Ltd [1987] 1 WLR 336 and Hunt v. Severs [1994] 2 WLR 602.

[291] Parry v. Cleaver [1970] AC 1, Smoker v. London Fire and Civil Defence Authority [1991] 2 AC 502, Longden v. British Coal Board [1998] AC 653

[292] [A1/131]

[293] [A/191-192]

[294] There has been a typographical error. This amount should be $283,162.61.

[295] See preceding footnote.

[296] Defendant’s Summary of Quantum dated 10 March 2017 at p.2. I have deleted the 75% discount on account of pre-existing vulnerability that is contained in the defendant's calculations.

[297] Allied Maples Group Ltd. v. Simmons & Simmons (a firm) [1995] 1 WLR 1602 at 1614; Lai Jianxing v Sakoma (HK) Ltd [2012] 5 HKLRD 589 at pp.597-598 CACV 220 of 2011, 19 October 2012

[298] See witness statement of Chui Oi Yee (attaching with it an earlier witness statement of Choi Wai Sheung [B/182-202A]

[299] Appendix to Ms Choi Wai Sheung’s witness statement [B/194]

[300] [T/Day3/62(20-63(4)]

[301] [T/Day4/29(16)-(21)]

[302] [T/Day4/54(11)-(15)]

[303] [T/Day5/13(6)-(18)]

[304] [B/184]

[305] Table 7 [A1/241]

[306] Table 8 [A1/242]

[307] [F/208]

[308] Table 9 [A1/243]

[309] [B/1]

[310] This was wrongly stated to be 1.5% in AUARDS [A1/223].

[311] [A1/193]

[312] This was omitted from the Defendant’s Summary of Quantum dated 10 March 2017 at p.2. It appears in A1/224.

[313] See §§174 and 182 above.

[314] Defendant’s Summary of Quantum dated 10 March 2017 at pp.2-3. I have deleted the 75% discount on account of pre-existing vulnerability that is contained in the defendant's calculations.

[315] http://www.csb.gov.hk/english/retirement/185.html

[316] Nizami v. London Management Clubs Ltd [1985] 1 WLR 784

[317] See Phipps v. Brooks Dry Cleaning Services Ltd [1996] PIQR Q 100 in respect of the corresponding Ogden Tables

[318] Parry v. Cleaver [1970] AC 1, Smoker v. London Fire and Civil Defence Authority [1991] 2 AC 502, Longden v. British Coal Board [1998] AC 653

[319] Table 10 [A1/11/244]

[320] Table 9 [A/11/243]

[321] [2013] 1 HKLRD 634

[322] At §31.

[323] 7th Ed., at §§ 26-44

[324] See Auty v. National Coal Board [1985] 1WLR 784 and the discussion in Kemp & Kemp Vol 1 at 11-030 – 11-035: R.123:May 2012.

[325] See §§122 and 154 above.

[326] [1982] 1 WLR 816 at 825

[327] [1970] 2 QB 130 at 151F

[328] [1995] PIQR Q34 at Q34

[329] [1988] 1 WLR 847 at 860F

[330] Including non-personal injury claims.

[331] [2006] EWHC 2896 Comm

[332] [1993] PIQR Q156

[333] [1995] PIQR Q25

[334] [2005] PIQR Q32

[335] [2000] Lloyd’s Rep IR 657

[336] Including non-personal injury claims.

[337] HCPI 770 of 1995

[338] HCA 2495 & 2496 of 1977

[339] HCA 409/2005 19 December 2016

[340] Kemp & Kemp The Quantum of Damages Vol 1 at 21-031 (R.137: October 2015)

[341] HCA 409/2005 19 December 2016 at §47.

[342] Plaintiff’s Closing Submissions pp.69-76, defendant’s Reply Submissions §§24-26 and 51-58, [T/Day8/61-68]

[343] From §7 – 58.

[344] [T/Day8/69A-F]

[345] [B/1]

[346] Tab 4 in defendant’s Closing Submissions Bundle

[347] [T/Day8/65I]

[348] Defendant’s Chronology of Major Events of Delay p.9

[349] [T/Day8/63N-R]

[350] [F/219]

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女牙醫稱做過多手術傷關節 衞生署被裁定須賠償2080萬 ...

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