CACV 206 /2019
[2021] HKCA 256
IN THE HIGH COURT OF THE
HONG KONG SPECIAL ADMINISTRATIVE REGION
COURT OF APPEAL
CIVIL APPEAL NO 206 OF 2019
(ON APPEAL FROM HCPI NO 833 OF 2002)
________________________
BETWEEN
YEUNG LAI PING
Plaintiff
and
SECRETARY FOR JUSTICE
Defendant
________________________
Before: Hon Kwan VP, Cheung JA and Au JA in Court
Date of Hearing: 2 February 2021
Date of Judgment: 8 March 2021
________________________
J U D G M E N T
________________________
Hon Kwan VP (giving the Judgment of the Court):
1. On 1 April 2019, Bharwaney J gave judgment (“the Judgment ”) in favour of the plaintiff, Ms Yeung Lai Ping, against the defendant as the representative of the Hong Kong Government after a trial of eight days. The plaintiff was a qualified dental surgeon and was employed as a dental officer by the Department of Health (“DOH ”) at the material time. She claimed damages for personal injuries to her dominant right wrist, including an attrition injury to the triangular fibrocartilage complex (“TFC ”), which put an end to her dental career. The judge found DOH had breached its duty as an employer to the plaintiff by assigning to her excessive surgical extractions (“SX ”)[1] OMS&DU ”) of the North District Hospital (“NDH ”), on either 30 October 1999, alternatively, between September 1998 and October 1999. Damages were awarded to the plaintiff in the region of $22 million with interest.
2. This is the defendant’s appeal challenging the findings on liability and contending that the award should be reduced for a variety of reasons. Mr Paul Lam, SC appeared for the defendant on appeal with Mr Simon Lam, who was the trial counsel. Mr Ruy Barretto, SC appeared for the plaintiff as before, assisted by Mr Douglas Jones and Mr Eric Tsoi.
Background
3. The background matters relevant for this appeal may be summarised as follows. They are taken from the findings in the Judgment as well as from matters not in dispute.
(1) General background
4. 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 four and a half years. In September 1994, she resumed full time studies at the University of Hong Kong for a two-year degree in Master of Dental Surgery, which she attained 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.
5. After completing the Master’s degree, the plaintiff returned to private practice for a few months. In February 1997, she joined DOH as a dental officer. She was first deployed to work as a relieving dental officer in various Government dental clinics for civil servants and their dependents, for about 11 months.
6. The second posting of the plaintiff was in December 1997. She was deployed to work as a relieving dental officer in the Lam Tin School Dental Care Services, for about three months.
7. Her third posting came in March 1998. She took up an attachment post as a dental officer in the OMS & DU of Queen Elizabeth Hospital (“QEH ”). Her work in this posting was evenly distributed between consultations, conservative and periodontic work and oral surgery. Between April and June 1998, she performed only 21 SX. From July to September 1998, the number of SX increased to 38, 40 and 28 per month respectively. The judge found that this increase of SX did not cause any symptoms in her right hand and wrist and that prior to working at NDH, she did not experience any numbness or other symptoms in her right hand and wrist, either from dental work or from any other cause[2]
8. From time to time, the plaintiff also took up some additional work, on a voluntary basis, at DOH’s Yaumatei evening dental clinic, and received an honorarium for such work.
9. Her fourth posting was in September 1998, when she was posted to work as a dental officer in the OMS&DU of NDH. It is her work there over 13 months that is the subject of this litigation.
10. In February 1999, the plaintiff was confirmed to the permanent establishment of DOH.
(2) The plaintiff’s work in the OMS&DU of NDH
11. NDH was a newly established hospital in 1998. At that time, the OMS&DU of NDH had only two dentists, unlike a fully established hospital with three to four full time dentists. Dr Tsui Hing Chung Sunny (“Dr Tsui ”) was the senior dental officer posted there in March 1998. As mentioned, the plaintiff joined in September 1998. She worked under the supervision of Dr Tsui.
12. The plaintiff worked five and a half days a week, with alternate Saturdays off, from 9 am to 5 pm on Mondays to Fridays and from 9 am to 1 pm on Saturdays. A working day was split into two sessions, the morning and afternoon sessions. From September 1998 to June 1999, she worked in the operating theatre for two sessions a week and in her surgery for eight to nine sessions per week. Overall, she spent most of her working hours in her surgery.
13. Dental officers were required to file monthly returns on the treatments given to patients. The purpose of the returns was for workload monitoring and for statistical analysis for internal use. Clerical staff in the OMS & DU also recorded the work done on each patient according to what was written on the treatment record. At the end of each month, dental officers were given the statistics compiled by the clerical assistant based on their monthly returns for verification. For the OMS & DU of NDH, the statistics were submitted via Dr Tsui to the headquarters of DOH[3]
14. As did the OMS & DU of other hospitals, the OMS & DU of NDH handled referrals from public and private hospitals and doctors and dentists in public and private practice. After initial consultation, usually carried out by Dr Tsui, 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, that did not happen in practice. The booking schedule at NDH was very heavy. When she was first posted to NDH, her appointment book was already fully booked for three months, and more bookings were being made continuously thereafter.
15. From the end of September 1998 to October 1999, the average number of SX for the plaintiff was 1.65 per session. The heaviest workload in terms of SX per session was during late September 1998 to November 1998, being 2.16, 2.15 and 2.0 SX per session for those three months. Her workload lessened somewhat in December 1998 to July 1999, but the number of SX per session still ranged from 1.54 in May 1999 to 1.81 in February 1999. From October 1998 to September 1999, the plaintiff performed 710 SX. Over the same period, Dr Tsui performed 479 SX.
16. Despite the plaintiff’s heavy workload, Dr 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. But he did not respond to her request.
(3) The symptoms in the right hand
17. In late May to early June 1999, the plaintiff felt weakness in her right hand and nocturnal paraesthesia[4]
18. The plaintiff first consulted the orthopaedic doctor in NDH on 19 August 1999 and was prescribed pain relief medication and night splint. The consultation note stated as “impression”: “CTS right wrist” and “try arrange NCV[5] CTS ”) on 23 August 1999[6]
19. From 31 August 1999 to 30 September 1999, the work that was assigned to the plaintiff was considerable and included 43 SX.
20. By late September 1999, the increase in the severity of her right wrist pain, especially on exertion, together with her right hand paraesthesia, made dental work intolerable. The consultation note of the orthopaedic clinic of NDH on 30 September 1999 recommended to “rest the right hand for a short period of time” and scheduled the next appointment on 25 October 1999. The plaintiff was granted sick leave by the orthopaedic clinic from 4 to 23 October 1999. Dr Tsui knew that she was granted sick leave for her wrist pain during this period, as he had to make arrangements for relieving dental officers. He would have read the sick leave certificates and would have known their contents, which stated that she had right hand numbness and weakness, tenderness around right wrist and right wrist pain.
21. The consultation note of the orthopaedic clinic written on 25 October 1999 stated “symptom partly relief [sic] during the rest period”. According to a memo issued by the Kwun Tong Occupational Health Clinic dated 28 April 2000, the date of commencement of “Prescribed Occupational Disease” of the plaintiff, being CTS[7]
(4) The week of 25 to 30 October 1999
22. When the plaintiff returned to work after the end of three 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. Dr Tsui had not asked her whether she could manage to perform SX after she returned to work.
23. As mentioned earlier, the plaintiff’s appointment book was being filled continuously and could be fully booked months in advance. According to her appointment book for the week of 25 to 30 October 1999, insofar as SX was concerned, one SX was fixed on 25 October Monday, one SX on Tuesday, two SX on Wednesday, none on Thursday, one SX on Friday, and three SX for the morning session on Saturday. This was less than her SX workload before she went on sick leave on 4 October 1999. The staff of NDH did try to cancel some of her appointments. An appointment for SX on Wednesday afternoon was cancelled, and there were three cancellations for other procedures, on Monday, Thursday and Friday.
24. The plaintiff was worried about having to perform three SX on the Saturday morning. She did not however complain to Dr Tsui that she could not handle three SX in one session. The judge was unable to find on the evidence that Dr Tsui knew three SX had been assigned to her that morning[8] [9]
25. The three SX on Saturday were scheduled at 9 am, 10:15 am and 11:15 am respectively[10] [11] [12] [13]
(5) Treatment and assessment since November 1999
26. The plaintiff was seen by the orthopaedic surgeon of NDH on 1 November 1999. The sick leave certificate issued that day gave the diagnosis of “right carpal tunnel syndrome”. The consultation note of 22 November 1999 stated: “Since she is a dentist, need to use her right hand excessively, condition certainly will relapse after back to work”. She was given sick leave continuously from 1 November 1999 to 24 December 1999. Further sick leave was granted on various days intermittently in 2000. From 28 December 1999 to January 2000, when she resumed work in NDH, there was a relieving dental officer posted to NDH to assist her with her dental work.
27. From 15 November 1999, the plaintiff was under the care of Dr So Yat Cheong, the consultant orthopaedic surgeon of QEH. According to his medical report dated 28 February 2002, the diagnosis was right CTS and right wrist TFC tear with mild instability. Dr So opined that these two conditions could be inter-related to each other. The CTS could render her right hand weaker and thus more prone to produce wrist pain, and the right wrist problem could lead to increased strain on her right hand and aggravate the CTS problem. The plaintiff was treated with splintage programme and physiotherapy.
28. On 30 November 1999, the plaintiff consulted the medical officer in the Occupational Health Clinic in Kwun Tong for the first time. Following from that and on 10 January 2000, investigating officers of the Labour Department (an occupational health officer, an occupational hygienist and an assistant occupational hygienist) attended the plaintiff in her surgery at NDH to carry out a workplace assessment with the view to determine if her sign of CTS was work-related. The officers concluded that “there were numerous risk factors that could contribute to her right carpal tunnel syndrome: awkward posture, the use of a hand held vibrating tool, a tight working schedule” and “these factors were not mutually exclusive in contributing her right wrist condition”.
29. Subsequent to the workplace assessment, the senior occupational hygienist for the Commissioner for Labour sent a memo to DOH on 19 January 2000 and made these suggestions:
“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.”
30. With the plaintiff’s agreement, with effect from 31 January 2000, she was transferred to the School Dental Care Services in the MacLehose Dental Clinic, mainly supervising dental therapists, doing consultations and dental examinations, and occasionally doing short dental procedures for dental therapists. This was a temporary measure, as DOH does not have a dental officer post which does not require the performance of clinical duties.
31. In August 2000, MRI scanning on the right wrist was performed. The findings were compatible with focal tear of TFC. Because of persistent numbness, weakness and pain around the right wrist, the plaintiff underwent surgery at QEH on 1 August 2002 to release the carpal tunnel entrapment, repair the TFC and relocate the dislocated extensor carpi ulnaris tendon[14]
32. The writ in this action was issued on 25 September 2002.
33. After the hand operation, the plaintiff used a splint for her right wrist and tried to use her left hand to extract teeth. But this resulted in pain at the ulnar aspect of the left wrist and occasional numbness of the left hand. She was examined by Professor Leung Ping Chung (“Professor Leung ”)[15] Dr Yeung ”)[16]
34. On 31 March 2004, a second medical board at QEH made an assessment at the request of DOH. The plaintiff was assessed to be incapable of performing clinical duties and providing dental services to clients. On 23 April 2004, the medical board recommended that she should be invalided from the civil service as a result of her infirmity. On 24 July 2004, DOH informed the plaintiff that they could not find alternative placement for her and she would be invalided from the civil service on medical grounds under Civil Service Regulation 366. On 30 July 2004, DOH paid to the plaintiff employees’ compensation of $645,120. On 23 August 2004, she was retired on invaliding and since then received a monthly pension roughly one-third of her monthly earnings as a dental officer. She was 32 years old in October 1999 and 37 years old in August 2004. Her normal retirement age was 60.
35. Professor Leung examined the plaintiff again in September 2009, seven years after the surgery. He found that 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.” She was no longer suffering from CTS of her right and left wrists[17]
36. In their joint report dated 14 June 2012[18]
Main findings in the Judgment
37. The main findings in the Judgment may be summarised as follows.
38. On liability, the judge found and held that:
(1) The plaintiff suffered an attrition fracture of the TFC of her right wrist towards the end of the third SX on 30 October 1999[19]
(2) But for the work-related stresses which the plaintiff experienced on the morning of 30 October 1999, she would not have suffered the TFC injury on that day, so the strict test of causation in negligence is satisfied. Even if the ‘but for’ test was not satisfied, the judge would have found that the plaintiff’s work was a material contributing factor to her TFC injury[20]
(3) DOH breached its duty of care to the plaintiff by requiring her to carry out 3 SX on 30 October 1999 in that (a) DOH assigned 3 SX to her on 30 October 1999 notwithstanding knowledge of her right wrist problems; (b) DOH 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 CTS; and (c) 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[21]
(4) There should be no apportionment of causation for the purpose of quantifying damages as the TFC injury was indivisible[22]
(5) The plaintiff was not contributorily negligent[23]
(6) 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 and the beginning of October 1999, when she had to take three weeks’ sick leave. After her return from sick leave in the last week of October 1999, her right wrist continued to be weakened and vulnerable such that when she performed the third SX on 30 October 1999, she suffered an attrition fracture of the TFC of her right wrist[24]
(7) DOH was liable to the plaintiff in negligence on the alternative ground that she was assigned an excessive amount of SX to perform during the relevant period aforesaid in that: (a) DOH 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 CTS; and (b) 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[25]
(8) On the alternative basis of liability, there should be no apportion of causation for the purpose of quantifying damages as the plaintiff’s injury was indivisible[26]
In respect of quantum, the judge awarded damages for pain and suffering and loss of amenities ($325,000), loss of congenial employment ($150,000), pre-trial loss of earnings and expenses ($9,592,775, after deduction of employees’ compensation received), post-trial loss and expenses ($10,742,386)[27]
(9) Damages should not be discounted on account of the plaintiff’s pre-existing vulnerability, being 1 mm ulnar variance in the right wrist and the greater variance and propensity to develop CTS in the left wrist[28]
(10) There should be no deduction for the pension benefits received and to be received by the plaintiff so as to reduce the claims for pre-trial and post-trial loss of earnings, but this does not apply to the claim for loss of post retirement pension benefits as from the notional retirement age of 60[29]
The issues in this appeal
39. The issues in this appeal may be grouped under four areas.
40. The first area relates to the primary basis of liability, namely that the attrition injury to the TFC was caused by assigning 3 SX to the plaintiff on 30 October 1999. The issues raised in this area are as follows:
(1) whether the primary basis of liability was pleaded in the statement of claim;
(2) whether the plaintiff suffered an attrition fracture of the TFC of her right wrist towards the end of the third SX on 30 October 1999;
(3) whether the attrition injury to the TFC was caused by assigning 3 SX to the plaintiff on 30 October 1999;
(4) whether the defendant was in breach of its duty of care to the plaintiff by requiring her to carry out 3 SX on 30 October 1999;
(5) whether there should be apportionment of causation for the purpose of quantifying damages for the primary basis of liability; and
(6) whether there was contributory negligence.
The second area relates to the alternative basis of liability, namely 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 September 1998 to October 1999. The issues in this area are:
(7) whether the plaintiff suffered the attrition fracture of the TFC because her right wrist had been weakened and was made vulnerable from the excessive SX she was assigned to perform during the relevant period;
(8) whether the defendant was liable to the plaintiff on the alternative ground that she was assigned an excessive amount of SX to perform during the relevant period; and
(9) whether there should be apportionment of causation for the purpose of quantifying damages for the alternative basis of liability.
41. The third area relates to discount for pre-existing vulnerability. Issue (10) is whether the judge is correct in refusing to make any discount.
42. The fourth area is the deductibility of pension benefits. Issue (11) is whether the judge is correct in not making a deduction for the pension benefits received and to be received by the plaintiff in the claims for pre-trial and post-trial loss of earnings.
43. The 11 issues will be considered in the order set out above.
Whether the primary basis of liability was pleaded in the statement of claim (issue (1))
44. Mr Lam submitted that the primary basis of liability (that the plaintiff was assigned excessive SX on 30 October 1999) was not pleaded in the amended statement of claim (“ASOC ”) and the only basis of liability pleaded in §§3 and 4 of the ASOC was that the plaintiff was assigned an excessive workload “from September 1998 until about the end of January 2000”. Hence, it was wrong and unfair to allow the plaintiff to succeed on a basis which was not her pleaded case.
45. The ASOC did not plead the liability of DOH on an alternative basis. We do not think that matters. What matters is whether material facts upon which liability is founded (held by the judge to found the primary basis of liability) were pleaded in the ASOC such that the defendant should be made aware of material allegations of fact upon which liability was sought to be established.
46. §3 of the ASOC set out the material events in the course of the plaintiff’s employment “from September 1998 until about the end of January 2000” and described her workload and duties at the time and what would be involved in performing SX over a long period of time. Under the particulars of knowledge of the defendant of the risk of wrist injury in §3(7), it was pleaded among other things:
“(d) the Defendant knew that the Plaintiff exhibited evidence of right wrist pain at work, wearing a splint and consulting the Northern District Hospital Orthopaedic Clinic on 19 August 1999 for her wrist problems, being diagnosed with suspected carpal tunnel syndrome and being given sick leave from 4th to 23rd October 1999;
(e) the Defendant knew the Plaintiff’s [sic] was in pain with an injured wrist after her sick leave ended, in the week from 25th to 30th October 1999, and during which the Plaintiff was required to perform 3 surgical extractions in a Saturday morning session on 30th October 1999;
(f) in consequence the Defendant knew the Plaintiff suffered disabling pain and was given further sick leave from 1st November to 24 December 1999 by the Northern District Hospital Orthopaedic Outpatient Clinic.”
47. §3(8) then pleaded:
“In the premises, and after the Plaintiff’s complaint of pain and injury and presumptive diagnosis of 19th August 1999 and/or the sick leave from 4th to 23rd October 1999, the Defendant knew or ought to have known that the Plaintiff could not safely perform surgical dental extraction work without the risk of suffering further pain and weakness and injury to her wrist.”
48. §4 pleaded that by reason of the matters in §3, the plaintiff developed right wrist injury which included CTS, TFC disruption and dislocation of the right extensor carpi ulnaris tendon and particulars of negligence were given, among them was this allegation:
“(14A) Knowing of the Plaintiff’s condition and risks of injury to the Plaintiff’s wrist, Dr Sunny Tsui assigned an unreasonable surgical extraction workload to the Plaintiff as pleaded herein whereby the Defendant exposed the Plaintiff to further pain and damage to the existing right wrist injury and disability, by unreasonably continuing a surgical dental extraction workload in a Dental Officer suffering wrist injury.”
49. We think material facts in support of the primary basis of liability have been adequately pleaded in the ASOC.
50. Mr Lam complained that notwithstanding the above pleading, there was “no focusing” in the ASOC on the specific injury allegedly suffered on 30 October 1999. He also drew attention to the opening and closing submissions of the plaintiff at the trial which contained an identical paragraph (§2) stating that the attrition injury to the TFC in the plaintiff’s right wrist was “because she was assigned an unreasonable SX workload over the preceding 12 months”.
51. This is not a valid complaint. In paragraph §3 in the plaintiff’s opening and closing submissions, it was stated:
“Furthermore, when P showed symptoms and signs of wrist injury, she was not relieved of the onerous SX obligation and given rest from the pain provoking strenuous work.”
52. §60 in the plaintiff’s opening submissions set out in some detail the plaintiff’s contention that the DOH, with actual knowledge, failed to reduce SX when Dr Tsui and others knew that the plaintiff developed wrist problems in July, August and September 1999 and continued to assign intensive SX work to her “with 3 SX in a single session on 30th October 1999.” §61 went on to deal with “continuing aggravation led to more injury”[30]
53. It could hardly be said that the defendant was not made aware of the significance to the plaintiff’s case of the 3 SX performed on 30 October 1999. The plaintiff was cross-examined extensively on what led up to 30 October 1999[31]
54. There is no unfairness to the defendant even though the ASOC did not plead the defendant’s liability on the basis of a primary case and an alternative case. No alternative facts were relied upon, and the same mechanism of injury was continuing. The pleading point is without merit.
Whether the plaintiff suffered an attrition fracture of the TFC of her right wrist on 30 October 1999 (issue (2))
55. In §39 of the Judgment, the judge made a finding of fact that the plaintiff suffered an “attrition fracture” of the TFC of her right wrist towards the end of the third SX that she performed on the morning of 30 October 1999, and that she suffered excruciating pain in her right wrist as a result of the damage done to the TFC of her right wrist. The judge went on to say that he was supported in making this finding by the joint opinion of Professor 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”.
56. Mr Lam made the point that Professor Leung and Dr Yeung had not given any opinion on whether, and if so how, the third SX performed on 30 October 1999 had caused any injury to the plaintiff’s right wrist. Their joint opinion merely supported that repeated mechanical stresses on the wrist and TFC could cause “chronic damage”, which would connote a gradual process rather than a traumatic event happening at a specific point of time or date. And although the experts were in agreement that the plaintiff suffered from a tear of the TFC at the right wrist, they did not opine that her TFC tear was caused by repeated mechanical stresses on any particular date, let alone 30 October 1999. They did not give any opinion specifically on what the plaintiff had experienced on that day. Hence, there was no medical evidence to support the judge’s finding.
57. According to the report of Dr So Yat Cheong (who was the plaintiff’s treating doctor at QEH since 15 November 1999) dated 28 February 2002, the diagnosis was right CTS and right TFC tear with mild instability. It is not clear from the report when he made that diagnosis. There is a radiology report of QEH in August 2000 showing that the plaintiff had an MRI scanning of the right wrist on 11 August 2000 for “suspected TFCC tear”. The findings were “interruption of normal hypointense TFCC signal near its radial attachment” and “a focal perforation is suspected”. The impression was “focal perforation of the TFCC on its radial aspect”. Mr Lam submitted that the diagnosis of TFC tear was made in August 2000 and only provisionally.
58. Although none of the medical experts were asked to give an opinion as to any particular point in time when the plaintiff suffered a tear of the TFC at the right wrist, Professor Leung did mention in his report dated 29 February 2016 that “when wrist pain already exists after repetitive stress, the pain is evidence of chronic damage to the TFC. When excruciating pain is felt during active wrist activity, it is highly likely to indicate acute-on-chronic damage of the TFC.”
59. We have mentioned the evidence of the plaintiff as to what happened when she performed 3 SX on the morning of 30 October 1999 and the excruciating pain she suffered towards the end of the third case after completing the SX.
60. Further, it is important to have regard to another finding of the judge at §110 to understand his finding in §39 in a proper context. In §110, the judge found 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”, and “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”. In other words, the injury was an “acute‑on‑chronic damage of the TFC” as explained by Professor Leung.
61. Even though the medical experts were not asked to provide an opinion as to what specific injury might have been sustained by the plaintiff on 30 October 1999, there was evidence that the judge could logically infer and find that, given the vulnerable and weakened condition of the plaintiff’s right wrist, her strenuous, repetitive and prolonged wrist activity in performing 3 SX that day, and the excruciating pain she experienced indicated an “acute-on-chronic damage of the TFC”. It is pertinent to note that having carried out the 3 SX that day, the plaintiff was unable thereafter to resume her normal duties as a dental officer and perform SX, as the TFC could not function as a wrist stabiliser without severe pain. We agree with the plaintiff’s submission that the judge accurately called the injury to the TFC an “attrition fracture”. The tear was attritional in that it was a process of reducing strength or effectiveness through sustained attack or pressure, until there came a point in time when the disruption, perforation or tear occurred.
62. This is a finding of fact that the judge is entitled to make. To paraphrase Hunter JA in Ocean Tramping Co Ltd v Lee Kin-kai [1991] 2 HKLR 232 at 235I to 236E, this is a matter upon which the judge will be assisted by medical evidence but is not dictated to by it. He is entitled to use his common sense to fill a gap that is not wholly covered by the medical evidence. The law and medicine apply different standards. The requirement in law is proof on the balance of probabilities. Under the science of aetiology, doctors look for “clinical cause”, proof beyond reasonable doubt and perhaps beyond any doubt.
63. We do not think the judge was wrong in stating that his finding was supported by the joint opinion of Professor Leung and Dr Yeung that “repeated mechanical stresses on the wrist and TFC could cause chronic damage”. As explained earlier, properly understood and analysed, the “attrition fracture” was not an injury that occurred in one day, but was derived from a process of attrition brought on by excessive SX over 13 months. The 3 SX on 30 October 1999 was the straw that broke the camel’s back.
64. There is no basis to disturb the finding of fact that the plaintiff suffered an attrition fracture on 30 October 1999.
Whether the attrition injury to the TFC was caused by assigning 3 SX to the plaintiff on 30 October 1999 (issue (3))
65. In §40 of the Judgment, the judge stated that he preferred the opinion of Professor Leung and found that but for the work-related stresses the plaintiff experienced on the morning of 30 October 1999, she would not have suffered the TFC injury. In §41, he stated that even if he were to accept Dr Yeung’s opinion that her work was 20% to blame for the TFC injury, he would still find that a 20% contribution towards the damage was significant enough to be a material cause for the injury.
66. Mr Lam sought to attack the above findings on the ground Professor Leung had not opined that but for the work-related stresses on 30 October 1999, the plaintiff would not have suffered the injury. Further, the judge had not distinguished between the plaintiff’s work in general and the 3 SX she performed on 30 October 1999, and there was no evidence to support the finding that the 3 SX, in particular the third one, had materially contributed to her injury. He repeated his submission that the medical experts had not been asked to give an opinion of the relevance or significance of what the plaintiff experienced on 30 October 1999, or whether and how this would have any material impact on the overall clinical course of her TFC tear. There is no medical evidence that the 3 SX caused, or materially contributed to, the TFC tear. He also argued, somewhat inconsistently, that it is clear on the medical evidence the plaintiff already suffered the TFC tear before 30 October 1999 when symptoms had already appeared.
67. These contentions may be dealt with succinctly, as they overlap with those raised in issue (2).
68. As was held in Ocean Tramping Co Ltd v Lee Kin-kai , causation is essentially a matter for the judge, not for the medical experts. The injury sustained by the plaintiff on 30 October 1999, as found by the judge, was an attrition fracture of the TFC and of the nature of an “acute‑on-chronic damage of the TFC”. In finding that the plaintiff would not have suffered the attrition fracture but for the work-related stresses on 30 October 1999, the judge is entitled to draw on Professor Leung’s opinion regarding the main cause of the chronic damage and to draw a reasonable and logical inference from the evidence of the plaintiff’s condition before and after 30 October 1999 and what had happened in the course of carrying out the 3 SX. There is no valid criticism here.
69. As to the contention that the plaintiff already suffered the TFC tear before 30 October 1999, we agree with Mr Barretto this would seem unlikely, as the plaintiff could still use her wrist and had performed SX before she went on sick leave (43 SX were assigned to her from 31 August 1999 to 30 September 1999) and after (7 SX were performed from 25 to 30 October 1999). It was after carrying out 3 SX on the last day that she suffered excruciating pain. Chronic damage was caused to the TFC before 30 October 1999, the tear or perforation to the TFC occurred on 30 October 1999. There is sufficient evidence that the 3 SX caused or materially contributed to the TFC tear.
Whether the defendant was in breach of its duty of care to the plaintiff by requiring her to carry out 3 SX on 30 October 1999 (issue (4))
70. These two findings in §48 of the Judgment are challenged: (1) DOH 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 CTS; and (2) 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.
71. In reaching the above findings, the judge took into account these evidence:
(1) The evidence of defendant’s witnesses, Dr Lee Kwing Hong[32] Dr Cham ”)[33] [34]
(2) The literature and evidence referred to in §§114 to 116 of the Judgment. The literature included the material contained in chapters 5 and 5a of a major study entitled “Musculoskeletal Disorders and Workplace Factors” published by the US National Institute for Occupational Safety and Health in July 1997 (“NIOSH 1997 ”) and a paper published by Barbara Silverstein et al entitled “Hand-wrist disorders among investment casting plant workers” in September 1987[35] Silverstein paper ”). Dr Cham accepted that she was aware of the materials contained in chapters 5 and 5a on work-related hand/wrist muscular skeletal disorders including CTS and she had a soft copy of NIOSH 1997 in her office. The plaintiff’s expert on ergonomics, Ms Tamara James (“Ms James ”), identified the Silverstein paper (which found that CTS has a high correlation with highly repetitive jobs that require high amounts of exerted force) and testified that in 1998/1999, the evidence was “readily available” that there were certain risk factors that would contribute to musculoskeletal disorders such as CTS.
(3) The evidence of what happened before and after the plaintiff went on sick leave. Dr Tsui had noticed the plaintiff wearing a hand splint from late July or early August 1999 and knew that she had started physiotherapy although he was not sure when she did so. Despite this knowledge, the plaintiff was assigned considerable work, including 43 SX, from 31 August 1999 to 30 September 1999. On her return from sick leave in the last week of October 1999, and notwithstanding her condition was well known to Dr Tsui, 3 SX had been, and remained, assigned to her for the morning session of 30 October 1999. DOH, as the employer of Dr Tsui, must be imputed with the knowledge of Dr Tsui of the condition of the plaintiff’s right wrist and with the knowledge of its employee who had fixed 3 SX on the plaintiff’s appointment book for that morning[36]
72. Mr Lam attacked the findings along the following lines:
(1) The employer’s duty to deal with a risk of occupational disease is triggered by identification of the “date of knowledge” in the individual case. Looking at each case on its own facts, the relevant “date of the employer’s knowledge” will vary according, “not only to the general nature of the industry in its widest sense, … but also to the particular type of work within the industry that is under consideration, the tools used by the claimant, the nature and pattern of his use of them and the extent to which, having regard to the well known test of Swanwick J in Stokes v Guest, Keen and Nettlefold (Bolts and Nuts) Ltd [1968] 1 WLR 1776[37] Doherty v Rugby Joinery (UK) Ltd [2004] ICR 1272 at §§58, 59)
(2) An employer must keep up to date, but the court should be slow to blame him for “not ploughing a lone furrow”. “One must be careful, when considering documents culled for the purpose of a trial, … not to forget that they once formed part of a flood of print on numerous aspects of industrial life, in which many items were bound to be overlooked. However conscientious the employer, he cannot read every textbook and periodical, … nor can he necessarily be expected to grasp the importance of every single item which he comes across.” (Thompson v Smith Shiprepairers Ltd [1984] 1 QB 405 at 416C, 422D to E).
(3) The Occupational Safety and Health Committee (“OSHC ”) of DOH, of which Dr Cham was a founding member, was not established until 2007. Dr Cham’s knowledge about NIOSH 1997 was of no relevance to what DOH knew or ought to have known in 1998/1999, as her knowledge ought not to be imputed to DOH since she was not responsible for occupational safety at the time. From March 1999 to June 2001, a Senior Executive Officer, Ms Wong Yau Ling Elise (“Ms Elise Wong ”)[38]
(4) There was at the time no reported case of attritional TFC damage arising from working as a dentist. According to the memo dated 3 March 2000 of Dr Ho Hung Fun Albert, the Consultant Dental Surgeon (Operations), to the Chief Hospital Administrator, the plaintiff “could be only an individual case”, as there were over 25 dental officers of different ranks deployed in the OMS & DU in different hospitals, some of them had been working in conditions similar to the plaintiff for over 20 years and DOH had not received any report of CTS.
(5) None of the individual studies in NIOSH 1997 supported that repetitive strenuous dental activities related to wrist movements could cause upper limb musculo-skeletal disorders in dentists. Among the 30 epidemiological studies of occupational CTS listed in the tables of chapter 5a, only one concerned dental personnel (Liss et al 1995)[39] [40]
(6) At the material time, there were no published occupational health standards or guidelines concerning repetitive wrist movements of dental personnel in Hong Kong. There was no evidence on what would have been a reasonable number of SX to be assigned to the plaintiff within a fixed period of time in her situation. It would be impracticable to reduce or set a limit on the number of SX per session as there was no idea what that limit should be and it would impact adversely on the service provided to patients.
(7) The judge found that the plaintiff could complete an SX in about 40 to 45 minutes, during which time she would need to use the handheld drill for about 20 to 30 minutes. The 3 SX were scheduled at 9 am, 10:15 am and 11:15 am, so the plaintiff was not required to carry out repetitive strenuous activities involving her right wrist continuously without any break. There are different types of dental personnel with different degrees of clinical duties, and the job nature of a dentist is not monotonous requiring non-stop repetitive use of the wrist.
(8) The judge was unable to find Dr Tsui knew that 3 SX had been assigned to the plaintiff on 30 October 1999. In imputing relevant knowledge to DOH, the judge was wrong to combine the knowledge of Dr Tsui and the clerical assistant, resulting in finding that 3 SX were assigned to the plaintiff on 30 October 1999 notwithstanding knowledge of her right wrist condition. The knowledge of employees in a management position may be imputed to the employer but this may not be the case with the knowledge of a mere employee (Clerk & Lindsell on Torts (23rd ed) at §12-30). As for aggregating the knowledge of different officers within an entity, this may be done only if the person who knows of one piece of information is under a duty to ascertain the other piece of information known by another officer (K & S Corporation Ltd v Sportingbet Australia (2003) 86 SASR 312 at §108). There is no evidence that Dr Tsui was under a duty to ascertain the number of SX assigned to the plaintiff, or for the clerical assistant to inform Dr Tsui of the same.
(9) Even assuming that the judge was entitled to combine the knowledge of the clerical assistant and Dr Tsui, he was still wrong to hold that DOH knew or ought to have known of a reasonably foreseeable risk of injury in assigning 3 SX to the plaintiff on 30 October 1999 in light of these evidence which he had failed to take into account: the plaintiff’s condition had improved during the sick leave period of 4 to 23 October 1999; the treating doctor did not grant her further sick leave on 25 October, and no medical advice was given on the expiry of sick leave that the plaintiff was unfit to resume “usual duties”; the plaintiff did not complain to Dr Tsui that she could not handle 3 SX scheduled in one morning session.
(10) There is a tension between two conflicting principles: the employee’s autonomy and freedom to decide whether to take on the risk of injury to his health in continuing to work despite some susceptibility or infirmity on his part, bearing in mind that the relationship between an employer and employee is not that of a schoolmaster and pupil, so there is no legal duty on an employer to prevent an employee from doing work he is willing to do (Withers v Perry Chain Co Ltd [1961] 1 WLR 1314 at 1320); and the overall responsibility of the employer for the health and safety of his workforce (Coxall v Goodyear Great Britain Ltd [2003] 1 WLR 536 at §25). This tension is to be resolved by considering the “actual nature and extent of the known risk” (Coxall v Goodyear Great Britain Ltd at §§26 to 27)[41] [42]
(11) The judge’s view that the plaintiff should be posted to a less demanding position immediately upon her return from sick leave is unsustainable. Dr Cham’s agreement with the suggestion in cross-examination that the best time to offer a posting out would be when the dental officer had finished the sick leave was said with the benefit of hind sight. An offer to be posted out of NDH was made to the plaintiff on 22 November 1999[43]
73. The well-known test of what is expected of a reasonable and prudent employer, as stated by Swanwick J in Stokes v Guest, Keen and Nettlefold (Bolts and Nuts) Ltd at 1783D to F, is as follows:
“… the overall test is still the conduct of the reasonable and prudent employer, taking positive thought for the safety of his workers in the light of what he knows or ought to know; where there is a recognised and general practice which has been followed for a substantial period in similar circumstances without mishap, he is entitled to follow it, unless in the light of common sense or newer knowledge it is clearly bad; but, where there is developing knowledge, he must keep reasonably abreast of it and not be too slow to apply it; and where he has in fact greater than average knowledge of the risks, he may be thereby obliged to take more than the average or standard precautions. He must weigh up the risk in terms of the likelihood of injury occurring and the potential consequences if it does; and he must balance against this the probable effectiveness of the precautions that can be taken to meet it and the expense and inconvenience they involve. If he is found to have fallen below the standard to be properly expected of a reasonable and prudent employer in these respects, he is negligent.”
74. It is pertinent to bear in mind that the employer here is DOH. Prior to the setting up of OSHC within the Dental Service in 2007, as pointed out on behalf of the plaintiff before the judge[44] Dugmore v Swansea NHS Trust [2003] ICR 574 at 579A to B)
75. In 1996, the Labour Department published an “Occupational Safety Charter”, stating that it has drawn up a framework for introducing a “Safety Management System” covering all key aspects of concern in the workplace. The respective obligations of employers and employees under the safety management system were laid out. In respect of employers, among other obligations, they should develop a “Risk Assessment programme” which “identifies the actual and potential risks of each individual, with the aim of providing suitable equipment and use of it to ensure that risks are minimized”.
76. In May 1999, a “Policy Statement on Occupational Safety and Health” was promulgated by DOH at the request of the Commissioner for Labour, spelling out the responsibility of the management and staff of DOH in implementing the safety policy. The policy statement was disseminated by Ms Elise Wong to all divisions and units of DOH, with a request that it should be displayed in the office/clinic/centres for general notice. In her covering memo dated 25 May 1999, Ms Wong emphasised: “Most occupational accidents can be prevented if proper thought is given to the risks involved in the work and the relevant precautions are taken. It is the responsibility of each and every one in the Department to achieve this goal.”
77. Under section 15 of the Occupational Safety and Health Ordinance, Cap 509, medical practitioners are required to notify occupational diseases to the Commissioner of Labour. In June 1999, legislative changes were made by adding two notifiable occupational diseases, one being CTS[45]
78. It is not the case that DOH was “ploughing a lone furrow” in seeking to discharge its duties to the plaintiff as a reasonable and prudent employer. Risk of injury to the forearm, hand and wrist from repetitive activity has been appreciated for “many years”. A brief history on this was given in Munkman on Employer’s Liability (13th ed, 2001) at §7.40, dating from 1818. §7.32 of the same work referred to the publication of the Health and Safety Executive in the UK in 1990 entitled “Work-related upper limb disorders: a guide to prevention” (“HSE 1990 ”). And the earlier edition of Munkman (12th ed, 1995) gave an overview of “numerous recent decisions” on work-related upper limb disorders (“WRULD ”) arising from repeated movement of the hands and arms which include conditions such as CTS and the like (at pages 119 to 120) and discussed cases dealing with the instruction and warnings that should be given by the employer (at pages 116 to 117).
79. HSE 1990 and other literature available at the material time[46]
- “Ergonomics and Cumulative Trauma Disorder” by Thomas J Armstrong[47]
- HSE 1990[48]
- “Symptoms of the neck and upper extremities in dentists” by Ewa Milerad and Lena Ekenvall[49]
- “Neuropathy in female dental personnel exposed to high frequency vibrations” by Ingrid Akesson et al[50]
- “Occupational health problems among dental hygienists” by Nils Jacobsen and Arne Hensten‑Pettersen[51]
- “Dental Workers, Musculoskeletal Cumulative Trauma, and Carpal Tunnel Syndrome: Who is at Risk? A Pilot Study” by Valerie J Rice et al[52]
- “Musculoskeletal symptoms in New South Wales dentists” by E D Marshall et al[53]
- “Quantifying work load in neck, shoulders and wrists in female dentists” by I Akesson et al[54]
80. Similar to his criticisms of the judge’s reliance on NIOSH 1997 and the Silverstein paper, Mr Lam emphasised that some of the literature and studies mentioned above do not deal with occupational risk factors involving dental personnel, and that they are just general studies of a variety of workers and do not focus on CTS as an occupational disease. He pointed out that of those studies that concerned dental personnel, they do not focus on the work load in the nature of SX. And even for a study that does involve dental workers and focuses on CTS, the conclusion at the time was cautious and did not give generalised results.
81. We think that is missing the point. The focus of enquiry should not be narrowed artificially to dental workers and the specific injuries of CTS and attritional fracture of the TFC arising from an excessive workload of SX. In considering reasonable foreseeability, the question of risk is defined broadly, in line with Hughes v Lord Advocate [1963] AC 837, which was correctly applied by the judge in §48. This is well explained in Munkman on Employer’s Liability (17 ed, 2019) at §19.9:
“The immediate question is whether it can be shown that the claimant’s work should have been known to carry a risk of causing strains and pains to the forearm, hand and wrist … Neither the precise extent of the damage, nor the precise manner of its infliction need be foreseeable. If the consequence is one which was within the general range which might be foreseen (and was not of an entirely different kind which no one would anticipate) then it is within the rule that a person who has been guilty of breach is liable for the consequences. The cases decided on work related musculo-skeletal disorders have regarded strains and pains in the forearm, hand and wrist as belonging to the general class of injury that one might foresee from repetitive tasks involving the frequent use of the muscles of the hand and forearm, and often the application of force through the hand and fingers. As such, the precise definition of the injury (whether … carpal tunnel syndrome etc) is not a matter of critical importance so far as either knowledge or foreseeability is concerned.”
82. We are inclined to think that in 1998/1999, there was a considerable body of literature on WRULD and the associated occupational risk factors which included repetitive and forceful exertion of the wrist, mechanical stress, certain postures and vibrations. The studies and literature provided guidance on preventive measures and avoidance of the occupational risk factors. That there was a rarity of WRULD among the dental workers of DOH is no justification for DOH not considering the principles relating to WRULD, which were widely known by 1999. Nor do we think it matters that there were no published occupational health standards or guidelines in Hong Kong at the time concerning repetitive wrist movements of dental personnel. As accepted by Dr Tsui in cross‑examination, the inherent risks in relation to dental work are known and it is common sense that people who use their hands and wrists a lot are vulnerable to wrist problems[55]
83. It is immaterial that the OSHC within the Dental Service was not set up until 2007, or that an executive officer and not a dental officer was responsible for matters of occupational safety and health within the Dental Service prior to 2007. Whether Dr Cham had actual knowledge of NIOSH 1997 in 1998/1999, and if so whether her knowledge should be imputed to DOH notwithstanding she was not then responsible for occupational safety matters are of no significance. DOH would be put on notice of matters it ought to have known concerning the risks inherent to and associated with the type and pattern of work of the dental workers in its employment, especially with its greater than average knowledge as a public department of health.
84. As for knowledge concerning the plaintiff’s workload in particular the SX assigned to her, DOH had from 1995 an evaluation system for the Dental Service known as the Efficiency Index for calculating the average time spent on various tasks by dental officers including tooth extraction. And for many years, it had maintained a system of monthly returns for monitoring the workload of dental officers and for statistical analysis. As the officer in charge of the OMS&DU of NDH, one of the duties of Dr Tsui was to monitor regularly the bookings of appointments[56]
85. As a reasonable and prudent employer, DOH had the duty to consider the plaintiff’s capabilities and condition and review and adjust her workload of SX in light of its knowledge acquired by Dr Tsui of these matters: the plaintiff wearing a hand splint since July/August 1999; the medical and physiotherapy treatment she was given; and the three-week sick leave given to her in October 1999 on account of her wrist problem. Even if the failure to take action earlier might be excused because Dr Tsui was on leave for a good part of August, the three-week sick leave in October should be sufficient warning that urgent and timely measures had to be taken to reduce, if not remove, the occupational risks to which the plaintiff was exposed. We do not consider it of any importance that the orthopaedic clinic did not grant further sick leave on 25 October. The consultation note of 30 September 1999 recommended resting the right hand for a short period of time. Notwithstanding the three-week rest from dental work, the consultation note of 25 October stated that the symptom was only partly relieved during the rest period. Had anyone given proper consideration to the plaintiff’s condition, it is clear that she should not be assigned the workload of SX at the same rate as before on her return from sick leave.
86. That Dr Tsui was unaware of 3 SX being assigned to the plaintiff on the morning of 30 October 1999 could not be a reason to absolve DOH from liability. Nor could DOH be exonerated on the basis that the clerical assistant had no knowledge (if the assistant was indeed ignorant) of the plaintiff’s condition in assigning the 3 SX to the plaintiff. As the officer in charge of the clinic, it was incumbent on Dr Tsui to find out whether SX had been assigned to the plaintiff, as it was his duty to monitor regularly the bookings of appointments and the workload he assigned to the plaintiff. Further, as the plaintiff’s supervisor, it was incumbent on him to instruct the clerical assistant about the plaintiff’s condition on return from sick leave, and to see to it that the assistant would assign less strenuous and reasonably safe work to her. Without Dr Tsui’s instruction and approval, the assistant could hardly be expected to change the bookings for the plaintiff.
87. We do not think the plaintiff had a real choice or realistic freedom in declining to do SX on her return from sick leave. As the judge had found, Dr Tsui did not even ask the plaintiff whether she could manage to perform SX on her return. He had told the plaintiff that he would not change the schedule for her. The judge also found that any complaints of the plaintiff would not have resulted in the rescheduling of the 3 SX fixed for 30 October 1999[57]
88. Neither Dr Tsui nor any one in DOH had, on the plaintiff’s return from sick leave, weighed up the risk in terms of the likelihood of injury occurring and the potential consequences if it does, or balance this against the probable effectiveness of the precautions that can be taken. Prior to the intervention of the investigating officers of the Labour Department, which followed upon the plaintiff consulting the Occupational Health Clinic on 30 November 1999, and until suggestions were made by the Labour Department to DOH in the memo of 19 January 2000, there is no evidence that DOH had identified and assessed the actual and potential risks of the plaintiff on her return from sick leave, with the aim of minimising the risks she would be exposed to in assigning duties to her. As stated in the memo of Ms Elise Wong dated 25 May 1999, “most occupational accidents can be prevented if proper thought is given to the risks involved in the work and the relevant precautions are taken”. The Risk Assessment System in the Occupational Safety Charter was not put in action. The offer to post out the plaintiff to a less demanding position, first made on 22 November 1999, was far too late.
89. In our judgment, the liability of DOH is clear. There was clear evidence it was reasonably foreseeable to DOH that requiring the plaintiff to carry out 3 SX on 30 October 1999 would cause further damage to her wrist, which was already in a vulnerable state. The actual nature and extent of the risk of injury, which DOH knew or ought to have known, was such that precautions should have been taken in assigning jobs to the plaintiff which would require strenuous and continuous exertions of her wrist. The failure of DOH in this regard was below the standard properly expected of a reasonable and prudent employer and it was negligent.
Whether there should be apportionment of causation for the purpose of quantifying damages for the primary basis of liability (issue (5))
90. The judge held that there should be no apportionment of causation for the purpose of quantifying damages. This was on the premise that if he were to accept Dr Yeung’s opinion that the plaintiff’s work should be responsible for 20% of any impairment arising from the TFC injury and the positive ulnar variance of 1 mm of her right wrist was a predisposing cause for the TFC injury and 80% responsible[58] [59]
91. In BAE Systems (Operations) Ltd v Konczak [2018] ICR 1, it was held that an injury is to be regarded as single and indivisible “where there is simply no rational basis for an objective apportionment of causative responsibility for it” (at §56) and “one well-recognised type of case where there is a rational basis for an objective apportionment is where an industrial injury has become worse as a result of exposures at work over a long period, for only part of which the defendant employer is legally responsible. Examples are claims for noise-induced hearing loss, asbestosis or vibration white finger. In such cases the court can make an assessment, however broad-brush, of the degree of disability attributable to exposure during the period for which the particular employer is responsible” (at §58).
92. Mr Lam contended that the judge is wrong to hold that the TFC injury was indivisible. The judge had only considered whether the TFC injury was divisible in relation to the plaintiff’s structural variance of her wrist and had overlooked the TFC injury was caused by repeated wrist stresses related to her dental work in general and as such the injury ought to be divisible. The plaintiff had started to practise as a dentist in January 1990 and had performed a large number of SX before 30 October 1999. The chronic damage was likely to have begun soon after she worked as a dentist, and might have deteriorated faster after she worked at NDH. She already had symptoms in May to June 1999. It is wrong to require DOH to be responsible for the entirety of the damage caused by the TFC injury. The amount of stresses she experienced on one single day on 30 October 1999 must be negligible compared to the stresses she experienced for over nine years since working as a dentist or over one year before she worked at NDH. The proportion of loss and damage attributable to DOH’s breach of duty, upon such apportionment, “must be de minimis (so that no award should be made)”. In any event, DOH should only be liable for the exacerbation of her injury and any loss and damage caused thereby attributable to the 3 SX on 30 October 1999, in particular the last one. Since the plaintiff had started to practise as a dentist in January 1990 and had performed many SX before 30 October 1999, coupled with the structural variance of her right wrist, a very substantial discount, say 90%, should be made.
93. We do not accept Mr Lam’s submissions.
94. The simple fact is that prior to the plaintiff working at NDH when she was assigned a great number of SX (averaging 1.65 SX per session in the 13-month period), there was no medical, work-related or other evidence of wrist-related symptoms or disability in the plaintiff at any time during her previous dental career of eight and a half years. The assertion that the TFC injury is divisible on account of dental work in general over the plaintiff’s entire career is contrary to the evidence and the judge’s findings.
95. The plaintiff, who had no symptoms of wrist injury until she was subjected to working conditions likely to cause such injury, and when it is shown that the injury started in a way typical of a wrist injury caused by such conditions, has thereby established a prima facie presumption that her wrist injury was caused by those conditions (Gardiner v Motherwell Machinery and Scrap Co Ltd [1961] 1 WLR 1424 at 1429, per Lord Reid). This presumption has not been displaced by DOH.
96. The judge is entirely correct in not making an apportionment of causation of the TFC injury, as there is “simply no rational basis for an objective apportionment of causative responsibility for it”.
Whether there was contributory negligence (issue (6))
97. The allegations of contributory negligence pleaded in §17A of the amended defence are that (a) the plaintiff voluntarily took up or continue to take up dental work at DOH’s evening dental clinic in Yaumatei, when she already found the workload at the OMS & DU of NDH excessive and/or when she was already suffering from pain or injury in her right wrist; and (b) she rejected Dr Tsui’s suggestion that she be posted out of NDH in October 1999 upon her return from sick leave. These allegations were not pursued at the trial[60] volenti non fit injuria (also not pleaded in the defence): that she could have taken steps to reduce the SX appointments for 30 October 1999; that she had failed to complain to Dr Tsui she could not handle 3 SX in one session; that she should have stopped work and refused to carry out the third SX when her wrist became increasingly painful. The judge found on the evidence some of these allegations are not made out and in any event should not be considered as they were all unpleaded[61]
98. Mr Lam contended that even if these allegations had not been sufficiently pleaded, in the absence of material prejudice to the plaintiff, it was wrong and unfair not to allow the defendant to rely on them just because they were unpleaded, as the plaintiff had been cross-examined on those matters. He argued that it was wrong to hold that appointments of SX would not be rescheduled if the plaintiff had complained, as the plaintiff could cancel appointments “subject to approval” and there was no evidence that approval was refused on any previous occasion. He again made the point that as a professional the plaintiff was in the best position to judge for herself whether she should continue with the SX on 30 October 1999. He submitted that the judge should have found contributory negligence to the extent of 50%.
99. Mr Barretto submitted that it would not be unfair to disallow the defendant to rely on the unpleaded allegations for contributory negligence. What was put to the plaintiff in cross-examination was that her wrist condition was not as bad as she described and that she did all 3 SX uneventfully[62]
100. It would be unfair to the plaintiff to allow the defendant to run an unpleaded case of contributory negligence that she had consented to the breach of duty of DOH and to accept the risk of injury and was liable for conducting SX despite her increasing pain. This line of defence is fact and evidence sensitive. To allow the defendant to raise these allegations on appeal when the appeal court does not have before it all the facts bearing on these allegations would be contrary to the principle in Flywin Co Ltd v Strong & Associates Ltd (2002) 5 HKCFAR 356 at §§37 to 38.
Whether the plaintiff suffered the attrition fracture of the TFC because her right wrist was weakened and made vulnerable from the excessive SX she was assigned to perform during the relevant period (issue (7))
101. The judge found in §110 that the plaintiff suffered the attrition fracture of the TFC because her right wrist had been weakened and was made vulnerable from the excessive SX that she was assigned to perform during the relevant period from the end of September 1998 to the beginning of October 1999.
102. Mr Lam attacked the above finding on causation along these lines:
(1) The judge wrongly relied on, inter alia, the ergonomic evidence from which he concluded that the Strain Index (“SI ”)[63] [64] [65]
(2) He was wrong to hold that the SI method as originally designed was suitable for use as a tool to assess the risks associated with the plaintiff’s work as a dental officer[66] [67]
(3) To establish causation for the alternative basis of liability, the plaintiff would need to establish that the excessive SX assignment during the relevant period caused or materially contributed to the TFC tear. The judge had failed to distinguish between (a) whether the plaintiff suffered the attrition fracture of the TFC because her right wrist had been weakened and was made vulnerable from the SX she performed during the relevant period or since she practised as a dentist; and (b) whether she suffered such injury because her right wrist had had been weakened and was made vulnerable from the excessive SX she performed during the relevant period. Causation could only be established if there was evidence on (b).
(4) There was no medical evidence that the plaintiff would not have suffered the TFC chronic injury, or that there would have been any material difference in this regard, even if the assignment of SX was reduced. Further, in the absence of any finding what would have been the “normal” workload for SX, there was no rational basis to consider whether the SX assigned to the plaintiff during the relevant period was excessive.
103. For the reasons given by the judge[68]
104. As for medical evidence, the judge had regard to the opinion of Professor Leung and Dr Yeung (who were in agreement) that the plaintiff’s TFC damage could be the result of both structural predisposition and repeated work-related strenuous mechanical stresses, that they would not be able to affirm her wrist problem was solely predisposed by the structural abnormality, and that both felt 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[69]
105. The judge is entitled to find causation established for the alternative basis of liability based on the ergonomic evidence, the medical evidence, and the workload of the plaintiff in terms of SX in the relevant period as compared to Dr Tsui and four comparable dental officers which was “twice and more than twice the amount of SX that 4 other dentists had to perform” and was excessive[70] [71] Ocean Tramping Co Ltd v Lee Kin-kai , causation is a matter for the judge based on all the evidence, direct and inferential, with the assistance of expert evidence and drawing on common sense.
Whether the defendant was liable to the plaintiff on the alternative ground that she was assigned an excessive amount of SX to perform during the relevant period (issue (8))
106. The judge found in §§117 and 121 that DOH knew or ought to have known that repetitive strenuous dental activities related to wrist movements could cause WRULD including CTS, that it was reasonably foreseeable assigning an excessive amount of SX to a dentist to perform would cause an unreasonable risk of injury and that DOH was liable in negligence on the alternative basis that the plaintiff was assigned an excessive amount of SX during the relevant period of the end of September 1998 to the beginning of October 1999.
107. Mr Lam repeated his earlier arguments in issue (4). We have already addressed those arguments.
108. He again made the point that there was no evidence and no finding as to a reasonable amount of SX that should be assigned to the plaintiff. He reiterated that notions of “overwork”, “excessive work” have meaning only if they appeal to some external standard, quoting from Koehler v Cerebos (Australia) Ltd at §29.
109. We do not think it necessary for the plaintiff to prove an external standard as to the recommended maximum number of SX a dental officer should perform in a day or over a period before it could be found that it was reasonably foreseeable to DOH the amount of SX assigned to the plaintiff over the relevant period would create an unreasonable risk of injury and damage to the wrist. As rightly submitted by Mr Barretto, where there was no known standard, the employer should act on the basis of his knowledge of inherent risks. DOH collected data on the workload of its dental officers for the purpose of statistical analysis and monitoring. DOH could see from its data that the average number of SX per session of the plaintiff during the relevant period was 1.65, whereas the figures for the four comparable dental officers were 0.64, 0.66 and 0.86[72]
110. As for Koehler v Cerebos (Australia) Ltd , it was concerned with psychiatric illness, not physical injury, of a part-time merchandising representative. The trial judge found on the evidence of those familiar with this type of work that the employee’s workload was very similar to that of a full-time employee and was excessive. It was held on appeal that little significance should be given to external or industry standard as there was no indication, whether explicit or implicit, that the employee had any particular vulnerability to psychiatric injury and no suggestion that her attempts to perform the duties required of her would put her at risk of such an injury. It was in that context that the High Court of Australia made the comment on external standard for excessive workload. The quotation relied on by counsel should not be understood as requiring in general that evidence should be adduced on some external or industry standard of workload before the court can properly find that the workload is excessive in a given situation.
111. Mr Lam further submitted the judge’s finding that the plaintiff’s workload was excessive based on the premise that her SX assignment was twice and more than twice the amount of SX of other dentists is “simplistic, unscientific and illogical”. Whether workload was excessive should not and could not depend on a single comparison between the plaintiff’s workload and the other dental officers. The judge failed to take into account that although Dr Tsui carried out 479 SX during this period (compared to 710 for the plaintiff), he was the more senior dentist and the SX performed by him “could be more difficult and complex”. The other dentists working in other hospitals had performed more extractions (permanent, deciduous and supernumerary teeth) than the plaintiff although she performed more SX. An uneven distribution of workload, by itself, does not logically imply that the workload of the plaintiff was excessive. Besides, SX was not the only type of dental work undertaken by the plaintiff at the material time and her SX assignments were interspersed by other types of dental work. There was no evidence that DOH knew or ought to have known what amount of SX assigned to the plaintiff for the relevant period would be excessive.
112. We do not accept the above submissions. We agree with Mr Barretto there is plainly a logical and factual basis for finding that the rate of SX undertaken by the plaintiff during the relevant period was unreasonable and causative of the wrist injuries. Whether some of the SX performed by Dr Tsui were more complicated is irrelevant. The judge had found that the plaintiff requested Dr Tsui to give her more consultations and a better rotation of a variety of dental treatments and space between the bookings for SX but he did not respond to her request[73]
113. There is no basis to disturb the judge’s finding of liability on the alternative ground.
Whether there should be apportionment of causation for the purpose of quantifying damages for the alternative basis of liability (issue (9))
114. The judge applied the same reasoning (in issue (5)) that as the plaintiff’s TFC injury was indivisible, there should be no apportionment of causation.
115. Mr Lam repeated his earlier arguments. Whereas he contended that a 90% discount should be made in arguing issue (5), he submitted here that a 50% discount should be made to take into account the structural variance of the plaintiff’s right wrist. We have addressed those arguments adequately.
Whether there should be discount for pre-existing vulnerability (issue (10))
116. Before the judge, the defendant sought a discount of 75% on account of the plaintiff’s pre-existing double vulnerability, being 1 mm ulnar variance in the right wrist and the greater propensity to develop CTS in the left wrist. The question is whether there is a strong possibility that some other event, or natural progression of the condition, would have brought about the plaintiff’s present state. That some other event in the present context would be the continued practice of dentistry.
117. The judge accepted the plaintiff’s evidence and found 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 (which would mean doing sophisticated repairs and not require repetitive strenuous work with the hand and wrist) and worked as such no later than three to four years from October 1999, and there was only a remote possibility that her continued practice in dentistry three or four years after October 1999 would have brought about her present state. As the judge found that the continued practice of dentistry would not have posed any risk to her pre-existing double vulnerability, he declined to make any discount of the damages awarded[74]
118. Mr Lam submitted the judge’s finding was wrong in that he did not give any reason why there was only a remote possibility that the continued practice of dentistry three or four years after October 1999 would have brought about her present state. He stressed that the plaintiff developed chronic TFC injury after practising as a dentist for about nine years, and some chronic damage must have been done before she was posted to NDH after practising for eight and a half years. If she had continued to practise for another three to four years, her wrist would certainly have been subjected to further repetitive wrist activities. The plaintiff was 33 years old in 1999 and her remaining working life was 27 years. There was no evidence that a prosthodontist’s work in the course of 20 years would not have caused the plaintiff to suffer the same disability and loss. The absence of evidence which could indicate when the chronic damage would occur is not a ground to deny making a discount, as judges are frequently required to make assessment of probabilities in qualitative terms based on the available evidence and this is done not by a clinical, mathematical approach or by intuition but in a way which more or less reflects the plaintiff’s condition based on the available evidence (Liu Chun Kow Joe v Lee Sau Wing [2008] 3 HKC 433 at §39). He contended that the plaintiff should not be awarded any loss of earnings after 2004 or any future loss of earnings or that the award of damages should be reduced by 50%.
119. The judge had preferred the opinion of Professor Leung and found 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 1 mm was only a minor cause of the TFC injury in that it made the plaintiff more vulnerable to unfavourable work-related manual stress[75] [76] [77]
120. Since the TFC damage was not caused when the plaintiff did ordinary dentistry work before she worked at NDH, and was only caused when she performed a large number of SX during the relevant period, the judge is entirely correct to find only a remote possibility that continued practice in ordinary dentistry work for three or four years after October 1999 would have brought about her present state. Further, the judge is entitled to find, on all the available evidence, the continued practice of dentistry (three or four years until the plaintiff would have qualified as a prosthodontist and thereafter as a prosthodontist) would not have posed any risk to her pre-existing double vulnerability.
Whether there should be deduction for pension benefits received and to be received by the plaintiff in the claims for pre-trial and post-trial loss of earnings (issue (11))
121. The plaintiff was invalided out of the civil service on medical grounds[78] [79]
122. After the plaintiff was invalided, she received “pension benefits”, the total amount of which up to December 2016 amounted to $2,866,959 (after deduction of tax). In the submission of her counsel at the trial, a concession was made that this amount should be deducted from her claim for pre-trial loss of earnings[80] Parry v Cleaver [1970] AC 1, Smoker v London Fire and Civil Defence Authority [1991] 2 AC 502 and Longden v British Coal Corporation [1998] AC 653. In gist, the pension payments received by the plaintiff after she was invalided out were not of the same nature as earnings so as to enable deduction from her loss of earnings claim. The pension payments 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”[81] Parry v Cleaver at 16H: “A pension is intrinsically of a different kind from wages … the true situation is that wages are a reward for contemporaneous work, but that a pension is the fruit, through insurance, of all the money which was set aside in the past in respect of his past work. They are different in kind.”
123. In respect of the claim for future loss of pension in that the plaintiff was invalided before her normal retirement age and was thus unable to make a higher earning related pension contribution, the judge accepted as correct her counsel’s concession that the amount of “pension benefits” that would continue to be paid to her (based on her “pensionable emoluments” and the length of her “pensionable service” when she was invalided in 2004) after her notional retirement at 60 should be deducted from the notional pension at the time of retirement (based on the assumed pensionable emoluments at the time of notional retirement) net of tax, as “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”[82] Parry v Cleaver at 20H to 21B:
“… in the earlier period we are not comparing like with like. He lost wages but he gained something different in kind, a pension. But with regard to the period after retirement we are comparing like with like. Both the ill-health pension and the full retirement pension are the products of the same insurance scheme; his loss in the later period is caused by his having been deprived of the opportunity to continue in insurance so as to swell the ultimate product of that insurance from an ill-health to a retirement pension. There is no question as regards that period of a loss of one kind and a gain of a different kind.”
124. One of the grounds in the Notice of Appeal is that the judge erred in declining to deduct the pension payments so as to reduce the claims for pre-trial and post-trial loss of earnings. In the Respondent’s Notice, in respect of this ground of appeal, it was stated that the plaintiff “concedes the pension payments should be deducted”.
125. The plaintiff issued a summons on 30 October 2020 to amend the Respondent’s Notice to “clarify” the above concession, which, as submitted on her behalf, was “too broad and wrong in law”. The amendments would state that the concession (“pension payments should be deducted”) only applies to the “disability pension payments” to be paid to her after her notional retirement at 60 and they are to be deducted from the claim for loss of retirement pension. She would seek to support the judge’s holding that no deduction of the pension payments received should be made from the loss of earnings claim before her notional retirement.
126. The summons was opposed by the defendant. Mr Lam contended there was undue delay in taking out the summons three months before the hearing of the appeal and the proposed amendments, which would amount to withdrawal of a concession, are unfair and prejudicial to the defendant. He submitted that the appeal court would not have relevant and sufficient evidence to deal with the issues that might arise as a result of allowing the amendments to the Respondent’s Notice. He contended that the plaintiff should not be allowed to argue the deduction point in this appeal in view of her counsel’s concession in the court below without an amendment of her statement of damages.
127. We disposed of the summons at the outset of the hearing of the appeal and allowed the amendments to be made to the Respondent’s Notice. We do not think it would be unfair to the defendant. No new issue is raised in allowing the amendments as this court would be considering the same issues and contentions as had been considered by the judge, based on the same evidence before him.
128. As for Mr Lam’s contention that no evidence was adduced as to the nature and characteristics of the pension payments and there is need to consider the legislative history and background so as to discern the legislative intention of the statutory scheme upon which the pension payments were made, he has not specified what further facts or documentary evidence may be required. If there are indeed such further materials, we have no reason to think that the defendant would not have searched for them in the three-month period or asked for further time to search for them.
129. We are satisfied there is no reasonable possibility that the state of the evidence relevant to the deduction point would be made materially more favourable to the defendant. It is not caught by the principle in Flywin Co Ltd v Strong & Associates Ltd .
130. Turning to Mr Lam’s arguments on appeal, he submitted that the judge was wrong not to accept the plaintiff’s concession on the ground it was wrong in law and complained that it was a material procedural error for the judge to do so without any application of the plaintiff to withdraw the concession and without giving the defendant an opportunity to make submissions. He contended it is highly unsatisfactory that this court does not have the benefit of a first instance judgment delivered after considering submissions by both parties and it would be unfair to require the defendant to argue this point of law, which is based on public policies, for the first time in the Court of Appeal.
131. We do not think there is any unfairness here. The point about deduction of pension benefits was a live issue at trial. The only part of the period for which the deduction point was not contested, which was covered by the plaintiff’s concession as alluded to by the judge, was the period from August 2004 to December 2016 for deducting the pension payments from the pre-trial loss of earnings. It would appear from the respective positions taken in the statement of damages and the defendant’s answer thereto that the parties had become confused by splitting up the period before the notional retirement at the age of 60 into pre-trial and post‑trial portions and making deductions from the claims for loss of earnings. The judge decided to correct the error of law on both sides, applied the law to facts which were not controversial and did not call for further submissions. The law as decided by the majority of the Law Lords[83] Parry v Cleaver has stood for fifty years and the case has been followed consistently in the UK[84]
132. Mr Lam then pointed to the statement of the judge in §167 that “the pension payments 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” and deduced from that “these pension payments are in the same position as insurance money and are not to be set off against the claim for loss of earnings”. He submitted that the judge’s understanding of the nature of the pension payments was wrong because the plaintiff’s entitlement to pension benefits is a right under the Pension Benefits Ordinance (section 5), paid out of the general revenue (section 6), and in respect of which the plaintiff was not required to make any contribution from her salary. Hence, the pension payments in the present context cannot be regarded the same in nature as insurance money and not to be set off against the claim for loss of earnings.
133. We do not think this factual error should make any or any material difference to the correctness of the judge’s reasoning. As stated by Lord Pearce in Parry v Cleaver at 37E: “[the pensions] whether contributory or non-contributory, flow from the work which a man has done. They are part of what the employer is prepared to pay for his services. The fact that they flow from past work equates them to rights which flow from an insurance privately effected by him. He has simply paid for them by weekly work instead of weekly premiums.”[85] Smoker v London Fire Authority [1991] 2 AC 502 at 526G, the ratio in Parry v Cleaver did not depend on the pension scheme being regarded as an insurance scheme or analogous to one. The ratio was that “the pension was an entitlement on retirement flowing from the claimant’s past service and contributions and was not affected by his ability to earn or recover money outside that occupation.”
134. Lastly, Mr Lam relied on the minority judgments of Lord Morris of Borth-y-Gest and Lord Pearson in Parry v Cleaver and submitted that the House of Lords in Smoker v London Fire Authority was in error in refusing to reconsider the minority opinions and following instead the majority judgments unanimously[86]
135. We might mention that the House of Lords considered the deductibility of incapacity pension from an award for loss of retirement pension in Longden v British Coal Corporation [1998] AC 653 and once again applied the majority judgments in Parry v Cleaver .
136. We are not persuaded by the minority opinions that the claims for loss of earnings should be reduced to the extent not only of all that a plaintiff is earning or able to earn in another employment but also of “all that his former employment still produces in the form of pension as a set‑off against lost earnings, no less than against loss of potential pension”[87] [88] [89]
137. We respectfully agree with the majority judgments which are sound in reasoning and logic and accords with fairness and justice. We have already quoted material parts of those judgments. The point common to all three judgments in the majority is that pensions are different from earnings and that the nature of each form of receipt was different, in a context where it is necessary to compare like with like[90]
138. To paraphrase the statements of Auld LJ in Smoker v London Fire Authority at 525H to 526C, the pension benefits received by the plaintiff upon being invalided from the civil service cannot be regarded as earnings or as substitute for earnings, such as sick pay. They were payable in respect of disablement from carrying out pensionable employment and were a reward for pre-injury contractual service. They were payable irrespective of the plaintiff’s ability to earn in another employment, and independently of any loss caused by the defendant’s breach of duty. There is no reason why the pension benefits received by the plaintiff upon being invalided should be brought into the computation of the claims for loss of earnings, defeating the purpose of the pension scheme in providing financial protection to the employee in the event of ill-health or injury.
139. As noted by Lord Pearce in Parry v Cleaver at 38C to D, by section 2 of the Fatal Accidents Act 1959, the legislature has by implication expressed a view on the fairness and justice of the matter and the public policy inherent in it in providing that in assessing damages in respect of a person’s death, “there shall not be taken into account any insurance money, benefit, pension or gratuity which has been or will or may be paid as a result of death”[91]
140. There is no good reason to depart from the majority judgments in Parry v Cleaver , which is settled law in the UK. We uphold the judge’s ruling there should be no deduction for the pension benefits received and to be received so as to reduce the claims for pre-trial and future loss of earnings.
Conclusion and costs
141. For all the above reasons, we dismiss the defendant’s appeal. There is no dispute that costs of the appeal should follow the event. We order the defendant to pay the plaintiff’s costs of the appeal, with a certificate for three counsel, and that the plaintiff’s own costs be taxed in accordance with the Legal Aid Regulations.
(Susan Kwan)
(Peter Cheung)
(Thomas Au)
Mr Ruy Barretto SC, Mr Douglas Jones and Mr Eric Tsoi, instructed by Ho Tse Wai & Partners, for the Plaintiff (Respondent)
Mr Paul Lam SC and Mr Simon K C Lam, instructed by the Department of Justice, for the Defendant (Appellant)
[1] As explained by the plaintiff, SX required continuous exertion of force. It did not just involve flap‑raising procedures for the removal of roots, mesiodens, etc, but also the removal of bone and cutting of teeth and that 99% of SX she performed involved bony impaction. She could complete an SX in 40 to 45 minutes during which time she would need to use the handheld drill for 20 to 30 minutes. Using a surgical drill did not reduce the strain on the wrist, when the drill was used continuously to cut very hard bone and teeth substance. In addition, she had to use her wrist for other procedures such as injection of anaesthetic, suturing and irrigation. When SX was performed in the operating theatre with a more efficient handheld drill, the time would be shorter and less force would be used. See Judgment §§12, 13, 15.
[2] Judgment, §11
[3] Witness statement of Dr Tsui dated 6 November 2003, §24
[4] An abnormal sensation such as tingling or numbness.
[5] Nerve conduction velocity test, to assess nerve damage.
[6] Judgment §23. See CTS assessment record of the Occupational Therapy Department of NDH, showing that the plaintiff was assessed on 23 August 1999, 17 September 1999 and 1 November 1999.
[7] The Occupational Safety and Health Ordinance, Cap 509 was enacted in May 1997. By section 15, medical practitioners are required to notify occupational diseases of an employee to the Commissioner for Labour. By the amendments made in 1999, two new notifiable diseases, one being CTS, were added in June 1999.
[8] Judgment, §29
[9] Judgment, §51
[10] Plaintiff’s appointment book
[11] Judgment, §28
[12] The judge mentioned in §39 of the Judgment that excruciating pain was felt “towards the end of the third case” and found the plaintiff suffered an attrition fracture of the TFC of the right wrist “towards the end of the third SX” when she suffered excruciating pain. It would appear that the judge was using the terms “third case” and “third SX” interchangeably, and he did not summarise the plaintiff’s evidence inaccurately as suggested in the Respondent’s Notice to Supplementary Notice of Appeal §14.
[13] Witness statement of the plaintiff dated 13 April 2016, §17; transcript of Day 2, pp 49 to 51
[14] Dislocation of the extensor carpi ulnaris tendon is part of the feature of instability of the distal radio-ulnar joint and is probably the effect from the TFC injury, see report of Dr Yeung dated 5 September 2003, §6.10.
[15] The orthopaedic expert for the plaintiff in this action.
[16] The orthopaedic expert for the defendant in this action.
[17] A mild degree of CTS was developed on the left hand within the year after the right hand had problems.
[18] The joint report was only concerned with the assessment of the plaintiff’s disability that could have resulted from her occupational injuries while she served as a dental officer.
[19] Judgment, §39
[20] Judgment, §§40, 41
[21] Judgment, §§45 to 49, 114 to 116
[22] Judgment, §§42, 43
[23] Judgment, §§50 to 52
[24] Judgment, §110
[25] Judgment, §§117, 118, 121
[26] Judgment, §§120
[27] Pursuant to leave granted by the judge, the awards for pre-trial and future loss of earnings and loss of pension benefits were varied in his decision on 16 October 2019 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.
[28] Judgment, §§147 to 153
[29] Judgment, §§167, 182, 190
[30] This was also covered in the plaintiff’s closing submission, dealing with the defendant’s evidence as well, §§244 to 248.
[31] As noted in the Judgment, §50
[32] The consultant in charge of all hospitals where DOH had OMS&DU.
[33] An acting principal dental officer whose duties included occupational health within the Dental Service of DOH. Dr Cham joined DOH as a dental officer in 1992. She held the position of Senior Dental Officer (Dental Service Central Office) 1 of Dental Service as from January 2014 and her duties included coordinating the implementation of occupational health and general safety measures within the Dental Service.
[34] Judgment, §47
[35] The Journal of Hand Surgery, Vol 12A, No 5, Part 2, p 838
[36] Judgment, §46
[37] At 1783D to F
[38] Ms Elise Wong has left the Civil Service and was not called to testify.
[39] A mail survey concerning CTS among 2,214 Ontario dental hygienists compared to 305 dental assistants who do not scale teeth and both groups had a low response rate of 50%.
[40] Being low participation rate, lack of detailed exposure assessment for repetitiveness, and self‑reported health outcome.
[41] A number of cases were cited by Mr Lam as illustrations of circumstances when an employer might or might not be under a duty to prevent a willing employee from doing work because of a risk of injury to his health: Withers v Perry Chain Co Ltd ; Kossinski v Chrysler United Kingdom Ltd (1973) 15 KIR 225; Henderson v Wakefield Shirt Co Ltd [1997] PIQR 413; Coxall v Goodyear Great Britain Ltd ; Koehler v Cerebos (Australia) Ltd [2005] HCA 15 (High Court of Australia)
[42] Dr Jackie Lau was posted to NDH in August 1998 as a relieving dentist for about six weeks and gave evidence for the plaintiff.
[43] Judgment, §52
[44] Judgment, §115
[45] By LN 147 of 1999. For CTS, it is in respect of “Any occupation involving repetitive use of hand-held powered tools whose internal parts vibrate so as to transmit that vibration to the hand, but excluding those which are solely powered by hand.”
[46] Some were referred to in the plaintiff’s closing submission quoted in the Judgment at §115.
[47] Hand Clinics Vol 2, No 3, August 1986. The author concluded that reported occupational risk factors include repetitive and forceful exertion, mechanical stress, certain postures, vibration and low temperature and recommended control of occupational risk factors to help prevent cumulative trauma disorders.
[48] This was issued by HSE to give guidance to employers as illustrating good practice and included a summary about the prevention of WRULD by engineering controls and organisational arrangements.
[49] Scand J Work Environ Health 1990; 16:129-134. The authors concluded that the high frequency of symptoms from the neck, shoulders and upper extremities of the dentists studied was probably related to their difficult work positions with cervical flexion and rotation, abducted arms and repetitive precision-demanding handgrips.
[50] Occupational and Environmental Medicine 1995; 52:116-123. The authors concluded that dental hygienists and dentists had a slight neuropathy, which may be associated with their exposure to high frequency vibrations and opined that development of safer equipment is urgent.
[51] Community Dentistry and Oral Epidemiology 1995: 23: 177-81. This paper dealt with a questionnaire survey on work-related health complaints among dental hygienists.
[52] International Journal of Occupational Safety and Ergonomics 1996, Vol 2, No 3, 218-233. The authors concluded that although factors known to be associated with the development of CTS have been identified, the aetiology is still being investigated. They opined that the results of the pilot study should be used to suggest trends and ideas for future research.
[53] Australian Dental Journal 1997; 42:(4): 240-6. The study describes the prevalence and distribution of symptoms of musculoskeletal disorders in New South Wales dentists and investigates the relationship between these symptoms and work practices.
[54] Int Arch Occup Environ Health (1997) 69: 461-474. The authors concluded that dentists are exposed to high load on the trapezius muscles bilaterally, and steep, prolonged forward bending of the head, and, for the wrists, the postures were constrained, but the dynamic demands were low.
[55] Transcript of Day 3, pp 66 to 67, 78
[56] Dental Treatment Procedures No A16, headed “Utilization of Clinical Time by Dental Officers”
[57] The defence of volenti non fit injuria was not pleaded as a defence. It should be specifically pleaded if it is sought to be relied on (Lau Kam Tai v United Soundfair Engineering Co Ltd & Ors [1999] HKCFI 1408 at p 23). Quite apart from not being open to DOH on the pleadings, it is not available on the facts as found.
[58] Professor Leung’s opinion was that although the positive ulnar variance could be considered a predisposing factor, this structural variation could have at most only made the plaintiff more vulnerable to work-related manual stresses and assumptions that a minor structural variance at the wrist would disable a young working person could not stand reasonable and logical analysis. The judge preferred Professor Leung’s opinion that the main cause of the TFC injury was the repetitive strenuous activities related to dental extractions, see Judgment §§35, 37, 40.
[59] Judgment, §§38
[60] Judgment, §52
[61] Judgment, §51
[62] Transcript of Day 2, p 54 lines 1 to 5
[63] SI is a semi-qualitative job analysis methodology that results in a numerical score. The SI score represents the products of 6 multipliers that correspond to 6 task variables: (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. SI scores greater than or equal to 7 are probably hazardous. See Judgment, §§57, 58 and Appendix.
[64] Judgment, §§105, 110
[65] In that it was at variance with the defendant’s ergonomic expert, Professor Chan Che Hin Chetwyn (“Professor Chan ”), who arrived at an SI score of 4.5, compared to the SI score of Ms James which was 54. The judge arrived at the SI score of 36 because although he agreed with the methodology adopted by Ms James, he found that the workload basis upon which the SI scores were calculated (i.e. duration of task per day) should be taken from the data used by Professor Chan as being more reliable than Ms James’ data. See Judgment, §§60, 100.
[66] Judgment, §§63 to 73
[67] Judgment, §§76 to 95
[68] Judgment, §§72, 73, 92, 104
[69] Judgment, §109
[70] Judgment, §§111 to 113, 118
[71] The judge did not use the SI to establish reasonable foreseeability of injury, but merely used the SI as evidence to support his findings on causation. See Judgment, §§106, 107
[72] Judgment, §112
[73] Judgment, §22
[74] Judgment, §§149, 153
[75] Judgment, §40
[76] “Ulnar Variance: Facts and Fiction Review Article” by L De Smet, Acta Orthopaedica Belgica , Vol 60-1-1994
[77] Judgment, §6
[78] Under regulation 366 of the Civil Service Regulations, see also section 11(1)(h) of the Pension Benefits Ordinance, Cap 99.
[79] Sections 10(1) and 11(1)(a) of the Pension Benefits Ordinance, Cap 99
[80] The plaintiff did not make any concession about deduction of such “pension benefits” from her claim for future loss of earnings, see Judgment at §182. For the same reason that applies to pre-trial loss of earnings, the judge declined to make any deduction for “pension benefits” from the claim for future loss of earnings.
[81] Judgment, §167
[82] Judgment, §§190 to 193
[83] The majority were Lord Reid, Lord Pearce and Lord Wilberforce, Lord Morris of Borth-y-Gest and Lord Pearson dissented.
[84] The cases were cited in Halsbury’s Laws of Hong Kong (2nd ed, 2018), Vol 44, §[340.215]
[85] See also Lord Wilberforce in Parry v Cleaver at 42E.
[86] The leading judgment was given by Lord Templeman. Lord Lowry also gave a short judgment, agreeing with Lord Templeman and the judgment of Auld LJ in the Court of Appeal, whose judgment he described as “admirable”.
[87] Lord Morris in Parry v Cleaver at 31C to D, quoting with approval the judgment of Winn LJ in the Court of Appeal [1968] 1 QB 195 at 212.
[88] Lord Morris in Parry v Cleaver at 32D to E
[89] Lord Pearson in Parry v Cleaver at 51G to H
[90] Lord Hope of Craighead in Longden v British Coal Corporation at 668F to G
[91] The equivalent provision in Hong Kong is section 7 of the Fatal Accidents Ordinance, Cap 22, which provides that “benefits which have accrued or will or may accrue to any person from his estate or otherwise as a result of his death shall be disregarded”.