Lange v O'Carrigan

Nature of case 1In these proceedings, the plaintiff, Ms Kelly Lange, claims damages from the defendant, Dr Timothy O'Carrigan, an orthopaedic surgeon, alleging negligence arising from two elective surgical procedures that he performed on 2 August 2011 and 23 September 2011. The proceedings are governed by the provisions of the Civil Liability Act 2002 ["CL Act"]. 2The first procedure comprised total hip replacement surgery to the plaintiff's left hip. That procedure resulted in lengthening of the plaintiff's left leg, a possible complication about which she had been warned before she agreed to have surgery. 3The post-operative lengthening in the plaintiff's left leg was, by differing methods of estimation explained in the evidence, variously estimated as being 2.8cm, 1.8cm and 1.1cm. 4The second procedure comprised remedial surgery to remove and replace the femoral prosthetic components to correct and equalize the leg lengths. In that procedure the true leg length discrepancy was measured to be 1cm.

Factual background 5On 2 August 2011, at age 46 years, the plaintiff underwent left total hip replacement surgery performed by Dr O'Carrigan using a non-cemented ceramic Medacta prosthetic hip system. The indication for that surgery was pre-existing osteoarthritis of her left hip. 6The plaintiff first reported a perceived post-operative lengthening of her left leg on the day she was to be discharged from hospital. When she drew that perception to the attention of Dr O'Carrigan, he suggested a wait and see approach in the hope that the apparent or functional leg length discrepancy would be biologically accommodated over time. At that stage of the post-operative recovery it was not possible for him to accurately measure the true discrepancy. The plaintiff's case was critical of the occurrence of that discrepancy. 7Leg length discrepancy of the kind experienced by the plaintiff was a rare but recognised post-operative complication about which she had been warned. Accepted practice at the time indicated that when leg lengthening was recognised following hip replacement surgery, it was not appropriate to re-operate immediately, and it was reasonable to wait and see if accommodation of the discrepancy occurred over time, unless there were indications to the contrary. 8Six weeks post-operatively, on 23 September 2001, Dr O'Carrigan took a different course to the wait and see approach he had initially adopted. On this latter occasion, after his re-assessment of the plaintiff, and after giving further consideration to the problem, he suggested, and then successfully performed, remedial surgery to correct the leg length discrepancy. The plaintiff's amended case was critical of the timing of Dr O'Carrigan's decision to re-operate without allowing time to pass to see if biological accommodation occurred. 9In the course of his evidence in chief given in these proceedings, and with the benefit of hindsight, Dr O'Carrigan conceded that in carrying out the first procedure, he had made an intra-operative mistake in the course of the selection of the size of the femoral stem component of the prosthesis, in that he had selected and fitted a size 2 femoral stem instead of using a size 1 femoral stem. That mistake influenced the consequent leg lengthening of which the plaintiff complained. 10In his evidence, Dr O'Carrigan acknowledged his error but nevertheless maintained that the intra-operative selection of the size 2 femoral stem component was a decision he had reasonably made at the time although it had resulted in leg lengthening. Those events were explained in step-by-step descriptive detail of the procedure in the oral evidence of Dr O'Carrigan and, to a degree, in the evidence of the expert witnesses. 11In the second procedure, Dr O'Carrigan removed the size 2 femoral stem and replaced it with a size 1 stem, and he attached a differently configured femoral neck component. In doing so, he corrected the plaintiff's left leg length discrepancy. 12In evidence, reference was made to several descriptions of leg lengthening. These were first, apparent or functional discrepancy, which are equivalent terms, and are based upon what the patient sees or feels, or what the trained observer is able to see without measurement, and secondly, true discrepancy, which is derived by a process of specialised methodical measurement. 13Apparent or functional discrepancy was not an accurate measurement as it was affected by posture. In contrast, true discrepancy is an actual measurable skeletal difference in length, and is an observation arrived at by both clinical and x-ray examination. Despite a greater degree of accuracy, that latter method of measurement also has the potential to be inaccurate due to the alteration of anatomical landmarks that occurs during hip replacement surgery. The context and significance of these different descriptions will be explored in greater detail in my findings. 14The factual and expert evidence concerning the above events requires analysis to determine whether there were any relevant breaches of the duty of care Dr O'Carrigan owed to the plaintiff, and if so, should this be characterised as amounting to negligence, having regard to the requirements of s 5B of the CL Act.

Credit 15No credit issues arose from the evidence of either the plaintiff or Dr O'Carrigan. I am satisfied that the plaintiff gave her evidence honestly, in a matter-of-fact and unembellished manner, truthfully, according to her best recollection and understanding of the events in question. I am also satisfied that Dr O'Carrigan gave his evidence honestly and truthfully, with due recognition of the limits of his recollection in the context of a busy orthopaedic practice. He answered questions put to him in cross-examination in an open, forthright manner. The minor extent to which his evidence and the evidence of the plaintiff differed on the content of post-operative conversations was not material, and did not raise a credit issue.

Case for the plaintiff 16As initially filed, the plaintiff's case was widely pleaded. Counsel appearing for the plaintiff at the trial was briefed only shortly before the hearing. He produced a document that narrowed the issues to allege that the first procedure had been performed negligently, in that the leg lengthening should not have occurred, and that in those events, the second procedure had been unjustifiably performed, in that it had been carried out too soon after the first procedure, without first waiting for about 12 months to see whether the discrepancy would be accommodated biologically by naturally occurring postural adjustment. 17The forensic focus upon that latter proposition arose from an aspect of the opinion expressed by the expert retained by the defence, and which was adopted on behalf of the plaintiff, thereby abandoning an earlier made claim to the effect that the plaintiff's leg lengthening ought to have been revised immediately after it had been recognised, and whilst the plaintiff was still in hospital. The original pleading of a case based upon various allegations of failure to warn was also expressly abandoned at the hearing.

Case for the defendant 18Dr O'Carrigan denied the negligence alleged. He claimed his mistaken selection and insertion of the size 2 femoral stem could only be characterised as erroneous by judgments made in hindsight, in circumstances where the intra-operative trial measurements and the fitting of the selected size 2 femoral stem was considered to have been a proper selection and fit at the time. He claimed that he had exercised the required due skill and reasonable care in the planning and in the course of carrying out that first procedure. 19In respect of the first procedure, on Dr O'Carrigan's behalf, it was argued that according to the requirements of s 5B and the provisions of s 5C of the CL Act, in the particular circumstances and events disclosed in the evidence, his concession of an intra-operative error of judgment and the rectification of that error did not justify a finding of negligence. 20In respect of the indication for, and timing of the second procedure, on Dr O'Carrigan's behalf, it was argued that in recommending and carrying out that second procedure, he should not be found to have been negligent because his professional advice and actions had been in accordance with what was widely accepted in Australia as competent practice by peer professional opinion: s 5O of the CL Act.

Array of expert evidence 21In support of the case for the plaintiff, expert opinion evidence was obtained from Dr Barry Bracken, an orthopaedic surgeon, and Dr Peter Conrad, a general surgeon. In support of the case for the defendant, in addition to his own factual evidence, Dr O'Carrigan relied upon expert opinion evidence from Dr James Sullivan, an orthopaedic surgeon. 22In considering the peer evidence adduced in these proceedings, it is necessary to deal with some matters arising from the submissions of the parties. 23Dr Bracken had not performed hip replacement surgery in recent years. Although he had never used the Medacta prosthetic hip system, as an orthopaedic surgeon, he had carried out over 1000 hip replacement operations, and he had used the anterior surgical approach. It was not suggested that as an orthopaedic peer, he lacked the professional qualifications for critically reviewing Dr O'Carrigan's treatment of the plaintiff. 24Dr Conrad, whose opinions were essentially in agreement with those of Dr Bracken, had never performed hip replacement surgery, although he had practised extensively as a general and trauma surgeon, and he is qualified to carry out medical assessments that involve orthopaedic issues. Objection was taken to Dr Conrad's qualifications for critically reviewing the treatment that Dr O'Carrigan had provided to the plaintiff. After an examination on the voir dire, it was determined that Dr Conrad's evidence should be admitted in the proceedings as the objections to his opinions, in reality, involved the question of what weight should be given to the aspects of his opinions that were in contention. 25Dr Sullivan's qualifications as an orthopaedic peer for expressing opinions on the matters in issue were not the subject of challenge. In his practice, he currently carries out hip replacement surgery, and in the past he has had occasion to use the Medacta prosthetic hip system.

Procedural matters 26Before analysing the evidence and identifying my findings of fact, it is necessary to say something about some matters of procedure. 27The timing of Dr O'Carrigan's concession in his evidence in chief of an intra-operative error of judgment was unfortunate for the parties in the sense that it had occurred at a stage of the proceedings when their positions had become entrenched, with substantial costs having been already incurred. The plaintiff's submission suggesting it was surprising that Dr O'Carrigan's concession of error had not appeared in any of the instructions to the expert retained by the defence. 28In my view, nothing turns on that submission as no credit issue arises. The earlier non-disclosure of that concession is of diminished significance, especially as beforehand, the plaintiff's legal representatives had not at any stage sought to pursue the procedural remedies of seeking early admissions (UCPR r 17.3), obtaining evidence before a hearing (UCPR r 24.3) or seeking answers to interrogatories (UCPR r 22.1) aimed at ascertaining the essential facts that were solely within the knowledge of Dr O'Carrigan or others present at the first operation, and which required consideration by the respective experts. 29There is little room for doubt that special reasons of necessity existed for the making of an order for interrogatories on matters of Dr O'Carrigan's knowledge and his clinical and surgical reasoning at the relevant time: Keating v South Sydney Illawarra Health Service (NSWSC, Hall J, No 20232 of 2005, 7 July 2006, unreported), at [17] and [20], following Haywood v Collaroy Services Beach Club [2005] NSWSC 1203, per Rothman J, at [15], and similar authorities. 30The absence of any procedural steps taken along the above lines has influenced the manner of assembly and the formation of the assumptions for, and the content of, the expert opinions obtained for the purpose of the proceedings, and the timeline of that process. 31In preparing for the concurrent expert evidence session in the proceedings, a process which was appropriately ordered by the List Judge at an interlocutory stage pursuant to consent orders prepared by the parties in the days leading to the hearing, the parties did not beforehand pursue any preparation involving the identification of an agenda for a meeting of the experts qualified by the respective sides, nor did they formulate questions to assist the experts and the court in the concurrent expert evidence session. Instead, the concurrent expert evidence proceeded without a meeting beforehand, in a less than ideal and hybrid form, as was dictated by those circumstances. In response to an invitation to do so, the parties made submissions on the costs consequences of those circumstances.

Application to amend defence: s 5I of CL Act 32The hearing of these proceedings took place over the course of 5 days between 2 and 6 September 2013, following which judgment was reserved. On 19 September 2013, the Court of Appeal delivered its decision in an unrelated matter: Paul v Cooke [2013] NSWCA 311. 33That case concerned the application of s 5I of the CL Act to a claim of medical negligence involving the materialisation of an inherent risk of stroke during treatment that comprised neurosurgical coil clipping of a cerebral berry aneurysm of the right anterior cerebral artery. 34The potential significance of the decision in Paul v Cooke to the present case was the statement at [70], to the effect that the concept of inherent risk was not confined to those risks that cannot be avoided by the exercise of reasonable skill and care. 35On the application of the defence, in the present case, on 27 September 2013, the matter was relisted for the purpose of further argument arising out of the potential implications to the present case, of the decision on appeal in Paul v Cooke. 36In the present case, beforehand, no defence had been pleaded pursuant to s 5I of the CL Act, although such a plea had been available if it had been considered to be relevant when the defence was filed. The proposed amendment seeking to rely on s 5I, which was opposed by the plaintiff, was in the following terms: "Further and in answer to the whole of the statement of claim, the defendant states that he is not liable in negligence for harm suffered by the plaintiff as a result of the materialisation of an inherent risk. Particulars Section 5I of the Civil Liability Act" 37Due to the unavailability of senior counsel for the defendant, leave was given to the parties to proceed by way of written submissions on the understanding that my reasons for determination of the application to amend would be incorporated into this judgment. Those reasons are as follows. 38There is no doubt that a discretionary power exists to order amendment of the pleadings at any stage of the proceedings to ensure the determination of the real questions on which the parties are at issue: s 64(1) and s 64(2) of the Civil Procedure Act 2005 ["CP Act"]. 39That discretion must be exercised according to the dictates of justice as required by s 58(1) of the CP Act, and according to the criteria specified in s 58(2) of the CP Act. 40The exercise of a discretion to enable a party to amend pleadings must be exercised in a manner that is just to both parties, however, limits must be placed on the ability of a party to effect changes to their pleadings, particularly if litigation is at an advanced stage: Aon Risk Services Australia Limited v Australian National University [2009] HCA 27, at [112]. 41On consideration of those criteria, a number of insurmountable obstacles preclude granting leave to amend the defence. 42First, in the lead-up to the hearing, during the interlocutory stages, neither party seems to have directed their energies to an important aspect of the overriding purpose of ensuring a just, quick and cheap resolution of the real issues in the proceedings by either arranging for, or in the event of a dispute as to appropriateness, seeking an order for, an early conference between the expert witnesses: s 56(1), s 56(2)(b)(v), s 56(3) and s 57(1) of the CP Act; UCPR, r 31.20 and r 31.24. 43It is plain from the content of the concurrent expert evidence session during the hearing of the present matter, that if the above processes and the required underpinning steps had been applied at an earlier stage of the proceedings, the true issues would have been identified and the opportunities for a less costly resolution of the proceedings would have been more readily available. 44Instead, if the amendment sought is granted, the parties would inevitably face the prospect of incurring further expense, delay and uncertainty whilst particulars were sought and provided, and after consideration, possible further expert evidence, if required, was sought and obtained. 45Secondly, the decision on appeal in Paul v Cooke was not the first time a defence pursuant to s 5I was applied in a medical negligence case. Whilst in the present case the defence legal advisors had not previously considered the availability of such a defence, it was always open on the known facts, particularly the facts known to the defendant. That was the very purpose of including in the defendant's consent form a reference to the risk of incurring a possible post-operative complication comprising leg lengthening. 46At the first instance, Paul v Cooke, in July 2011, s 5I was prominently argued at the trial: Paul v Cooke [2012] NSWSC 840, per Brereton J, at [2], [109] to [122], and in other places in the judgment. That section also appeared conspicuously in the reasons of the trial judge, which were available since 25 July 2012. This can be taken to have been known to practitioners versed in the area of medical negligence litigation. See also, Cox v Fellows [2013] NSWCA 206, at [184] to [189], published on 9 July 2013. 47Thirdly, in complex litigation involving allegations of professional negligence requiring resolution by reference to expert evidence, as is the case here, and contrary to the submission made by the defence arguing that no further evidence would be necessitated by allowing an amendment relying on s 5I, simple analysis dictates otherwise: s 58(b)(i) of the CP Act. 48In support of the application it was argued that the way in which the present case had proceeded, the issue of the materialization of an inherent risk of leg lengthening following total hip replacement surgery had emerged "in tandem with the evidence that all steps were taken to minimize the chance of that inherent risk". 49In further support of the application, it was further argued that the plaintiff would not suffer any prejudice if the amendment were to be allowed. It was also argued that the case would not have been run differently, and that no further evidence would be required from any party if a defence pursuant to s 5I was pleaded. 50For the reasons that follow, I do not accept those submissions. 51The defence submission in support of granting the amendment downplays the effect of the proposed amendment, and in doing so, glosses over the complex intricacies and consequences of the remarks by Leeming JA in Paul v Cooke at [60] to [80], where the definition and the nature of inherent risk within the terms of the CL Act was examined. 52The submission on behalf of the defendant is also incorrect because it ignores the consequences for the plaintiff, of the decision made on her behalf at the commencement of the trial, to abandon the pleaded failure to warn case. The submission also ignores the significance of the instances that arose in the course of the hearing in view of that decision, where on grounds of relevance the defendant successfully took objections to exclude evidence on aspects of the anterior surgical approach to hip replacement surgery. This necessarily limited the scope of the evidence. 53Therefore, at the very least, if the application under present consideration were granted, the plaintiff would have to be given leave to re-open her case to enable the calling of further evidence, not necessarily yet marshalled, and at a cost in terms of further uncertainty, expenditure and delay. That would be necessary for a fair and open contest on how the nature and the extent of general and specific inherent risks of leg lengthening after total hip replacement surgery, should be considered and evaluated in a re-pleaded case. 54Further, possible variables as to inherent risk arise for consideration in the form of questions of whether, and if so how, stratification of risks should be seen in connection with particular prosthetic devices, the available surgical approaches, the historical experience of the particular surgeon, the nature and content of advice that should have been given to the patient in accordance with the requirement of the exercise of reasonable skill and care, and how this all relates to the scope and the content of the duty of care owed by the operating surgeon. 55It is evident from the above analysis that significant prejudice arises to the plaintiff, which should not be glossed over in the interests of expediency that unfairly favours the interests of one party over the other. 56In those circumstances, and contrary to the submission by the defence that the plaintiff would not suffer any prejudice if the amendment were to be allowed as the plaintiff's case would not have been run differently, the above analysis suggests otherwise. 57It is not sufficient to speak in terms of materialisation of an inherent risk without an exploration of the context. For example, in the leading case on informed consent, the risk of materialisation of sympathetic ophthalmia following eye surgery was described as being a risk of 1 in 14,000 cases: Rogers v Whitaker [1992] HCA 58; (1992) 175 CLR 479. 58In contrast, in the present case, no evidence was called concerning the incidence of risk of leg lengthening following total hip replacement surgery. No evidence was tendered from within a body of published literature, if it exists, dealing with how risks said to be inherent in the procedure should be stratified in view of the known variables. These are, an anterior approach as distinct from a posterior approach, the use of the Medacta prosthetic system, or other systems, if there were material differences, and perhaps other matters that are best known to experts in the field. 59In considering these matters, it would appear that significant injustice would arise to the plaintiff in terms of delay and cost if the amendment were to be granted at this late stage of the litigation, especially where the plaintiff has abandoned her previously pleaded case of a failure to warn of the risk of leg lengthening: s 58(2)(b)(vi) and (vii) of the CP Act. 60For the above reasons, the application should be dismissed, with the defendant to pay the costs of the dismissed application.

Essential question to be addressed 61As a result, and without limiting the questions the parties wished to pursue with the experts, it was left to the court to formulate the initial and fundamental question to be addressed by the experts. This was essentially whether, on a review of the disclosed factual material, there was any evidence that Dr O'Carrigan had departed from the standard of care that was to be expected of an ordinarily skilled orthopaedic surgeon acting reasonably - if so why so, and if not, why not?: T186.7. The reasoning within the answers the experts gave to that question and the related questions that followed, illuminated the issues to be decided in the proceedings.

Facts 62In the paragraphs that follow, unless otherwise qualified, in addition to the already stated factual background, I set out my findings on matters of fact concerning the plaintiff's background, her pre-operative circumstances, the pre-operative radiology and consultations, Dr O'Carrigan's qualifications, the intra and post-operative circumstances of the first procedure, the post-operative course and events following the first procedure, Dr O'Carrigan's explanation of intra-operative error, the post-operative review, the decision by Dr O'Carrigan to re-operate, Dr O'Carrigan's explanations for the second operation, the plaintiff's subsequent post-operative recuperation, the medical and allied reviews of the plaintiff's condition, the plaintiff's residual disabilities, and the issue of mitigation of damage.

Plaintiff's background and pre-operative circumstances 63The plaintiff was born in 1965. At the hearing she was aged 48 years. She lives with her long-standing partner. Her daughter from a previous relationship, who is now aged 27 years, recently commenced living independently. The plaintiff took care of her physical fitness by maintaining an active lifestyle, both in terms of her leisure and domestic activities. 64On leaving school at age 15 years the plaintiff pursued work for various supermarket proprietors and retailers. She also did some process work in a factory. For about 15 years from 1994, she had worked for Woolworths, a supermarket chain. By the time she left that employment she had progressed from her initial position as a meat packer to holding a responsible managerial position in a suburban supermarket store. This work required her to carry out a variety of supervisory and administrative duties, including hands-on work involving physically lifting and carrying boxes weighing up to 10kg. 65Whilst in that employment the plaintiff found that she was ultimately working extreme hours. She found that towards the end of her working day she was limping, and over time, her limping had become worse. In those events, her work duties did not lessen, and she became stressed at these events. 66In about 2008, at age 43 years, the plaintiff was experiencing pain in her left groin and hip. She underwent x-rays and was ultimately diagnosed as having a severe form of osteoarthritis in her left hip. This was an unusual condition for someone of her age. Whether this was thought to be due to the effects of assumed Perthes's disease from her childhood years, or due to a slipped femoral epiphysis, diagnoses that were disputed by Dr O'Carrigan, did not require resolution, as such diagnoses made no actual difference to the undisputed need for the plaintiff to have hip replacement surgery due to the presence of osteoarthritis. 67As a result of the plaintiff's experience of worsening left hip problems she decided to give up her employment with Woolworths and to take up less stressful and less arduous employment as a care or support worker working in the disability sector. In that employment she has worked various hours for up to 5 days per week, with flexible shifts and ready availability of work, at times working up to 44 hours per week on the odd occasion. The work involved providing care to disabled persons. 68In order to further her career in the disability care sector, the plaintiff had undertaken studies to obtain qualifications in the form of a Grade IV Certificate in Community Services and Disability Care with a view to moving into managerial work within that sector. 69In the ensuing years following 2008, the plaintiff's experience was of evolving left hip pain becoming more severe. By March 2011, the plaintiff was having continuing pain in her left groin and experienced difficulty standing, sitting, and she had restrictions in her activities of daily living. In early 2011 she sought out medical advice for those problems. She was initially informed that it would be desirable for her to delay consideration of hip recommended replacement surgery until she reached the age of 50 years because of the life expectancy of hip prostheses. After some time she then sought out other advice. 70Before the plaintiff consulted Dr O'Carrigan, she had been referred to another orthopaedic surgeon at Royal Prince Alfred Hospital. Due to the unavailability of that surgeon, she saw another surgeon at that hospital who advised her that she could have hip replacement surgery on 6 June 2011. She was told this would be performed by a surgical registrar. She declined that opportunity and instead sought a referral to Dr O'Carrigan, as she was aware Dr O'Carrigan had previously operated upon her father with satisfactory results, and she had confidence in him. 71The plaintiff had a past history of episodic tachycardia. She had experienced some past episodes of stress in her personal life. This related to an incident when she had been assaulted and robbed. She had also experienced problems of stress in an earlier domestic relationship. In more recent times, in the course of her work as a care worker, she had also experienced some transient interpersonal problems in working with a difficult to manage client who was disabled due to brain damage. Otherwise, she had enjoyed good general health. 72The relevance of the plaintiff's earlier experiences of stress related to her reaction to post-operative events, in that it was suggested that as a result of those earlier events, she had thereby been predisposed to react adversely to subsequent stressors. 73Before consulting Dr O'Carrigan for advice and treatment, the plaintiff had undertaken some internet research about what was involved in hip replacement surgery, including the various anatomical approaches that could be taken for hip replacement surgery. As a result of that research the plaintiff believed that in her case an anterior approach to such surgery would involve less bleeding and require less recovery time.

Pre-operative radiology 74The pre-operative radiological investigations requested by the plaintiff's general practitioner commenced on 14 April 2008 with x-rays and CT scans of the left hip. The reported conclusion on the interpretation of those investigations was the presence of femoral acetabular impingement of the left hip with secondary osteoarthritis. The appearance of the right hip was reported to be unremarkable. 75Repeat x-ray investigation of both hips carried out on 21 April 2010 was reported as showing moderate to severe degenerative arthritis in the left hip. The right hip joint space was reported as being of normal appearance. 76Further x-rays and CT scans were carried out on 3 February 2011. On that occasion, the x-ray examination of the right hip joint space was reported as appearing preserved. On CT examination, the left hip was reported to have advanced osteo-arthritis with features suggesting femoroacetabular impingement. Dr O'Carrigan considered the cause of the plaintiff's left hip osteoarthritis to be acetabular impingement rather than Perthes's disease or a slipped femoral epiphysis. 77There was no issue that the radiological findings as summarised above warranted that the plaintiff be offered left sided total hip replacement surgery.

Consultation with Dr O'Carrigan before first procedure 78On 13 April 2011, with a view to possible hip replacement surgery, the plaintiff's general practitioner, Dr Samir Elsokkary, referred the plaintiff to Dr O'Carrigan for his investigation and management of the pain she was experiencing in her left hip. 79On 12 May 2011, the plaintiff attended Dr O'Carrigan's rooms at the Sydney Bone and Joint Clinic. At the time he gave his evidence, Dr O'Carrigan had no actual recall of the history that he had obtained from the plaintiff at that consultation however, the treatment information form he had annotated and completed when he saw the plaintiff at that time, provided relevant details 80That information form, and the associated records, show that in the context of the plaintiff's left hip arthritis, Dr O'Carrigan had recommended a total left hip replacement and he agreed to the appropriateness of using an anterior approach, the alternative being a posterior approach. The information form also recorded a number of potential complications which were discussed, including possible leg length discrepancy. The plaintiff also signed a hospital consent form on 12 May 2011, indicating that she understood the nature of the intended procedure and its attendant risks. 81The plaintiff agreed to the procedure suggested by Dr O'Carrigan and this was booked to take placed at the Sydney South West Private Hospital on 2 August 2011. In the meantime, in view of a prior medical history of paroxysmal hypertension and arrhythmia, Dr O'Carrigan referred the plaintiff for a pre-operative medical assessment to Dr Lance Day, a cardiologist. The results of that assessment were not in evidence but nothing turns on those results as the plaintiff was assessed as being fit for the operation. 82Dr O'Carrigan's pre-operative letter dated 12 May 2011 addressed to the referring general practitioner noted the plaintiff's legs were of equal length and noted his interpretation of the x-rays as showing advanced osteoarthritis of the left hip with osteophyte formation and loss of joint space. He confirmed the need for a left total hip replacement as the only way of providing pain relief and restoring function. He recommended fitting a ceramic on ceramic device and he agreed to perform an anterior approach. 83Although the anterior approach to hip replacement surgery raised some technical difficulties and challenges compared to the posterior approach, no issue arises from those facts as there is no criticism of the plaintiff's requirement for that approach to be taken, nor is there any criticism of Dr O'Carrigan's agreement to adopt that approach.

Dr O'Carrigan's qualifications 84Dr O'Carrigan is a specialist orthopaedic surgeon who has been in private practice since 1999. He has received post-graduate fellowship training in the assessment, treatment and management of leg lengthening. Amongst other areas of practice, he is a tertiary specialist who is consulted for treatment of leg lengthening issues. He estimated that about 30 per cent of his surgical practice involved joint replacement surgery, about 40 per cent of which involved hip replacement surgery. His qualifications and professional attainments as a specialist orthopaedic surgeon were not in issue, and these are set out in his curriculum vitae: Exhibit "1".

First operation - Intra-operative procedures 85The details of the operative procedure for replacement of the plaintiff's left hip came first, from Dr O'Carrigan's operation report dated 2 August 2011, a copy of which was sent to the treating general practitioner, secondly, the oral evidence of Dr O'Carrigan, and thirdly, from the hospital clinical notes. The hospital notes for the first procedure form part of Exhibit "B" between pages 151 to 235. A summary of the events of that procedure follows. 86The aims of total hip replacement surgery were described as being to relieve pain and improve function of the hip by removing diseased bony tissue, which would necessarily alter the surrounding anatomy, and to try and restore normal anatomy and biomechanics with the implantation of a hip prosthesis, using the unaffected opposing hip as a landmark or guide to establishing the appropriate positions for the placement of the prosthetic components at the operation site. 87Dr O'Carrigan explained that hip replacement surgery can be approached either laterally, anteriorly or posteriorly. He explained that the anterior approach had the advantage of being an inter-nervous and inter-muscular approach that passed through tissue planes in a way that did not involve cutting through muscles, although the lateral femoral cutaneous nerve was at risk of injury, which in fact occurred at some stage in the course of one of the plaintiff's surgeries. The evidence does not permit a conclusion as to which particular operation caused that injury. 88In his oral evidence, Dr O'Carrigan explained in detail, and without challenge, the multiple sequenced tasks and professional reasoning that lay behind his clinical decisions and surgical actions that comprised the first procedure that he had performed on the plaintiff. In providing his explanations, Dr O'Carrigan referred to a bundle of copies of radiographic imaging and a model of a prosthesis: Exhibit "2" and Exhibit "3". 89Dr O'Carrigan explained that the manner in which non-cemented prosthetic hip components are initially fixed is by means of mechanical interference in order to achieve a mechanical fit between the bony interface and the hydroxyapatite surface of the implanted device. This promotes a stable environment for bony ongrowth from the surrounding bone onto the implanted device, which over the course of the healing process, achieves long term biological fixation. 90Dr O'Carrigan explained that the entire array of components within the Medacta prosthetic system that was available to him for the operation comprised 10 graduated sized components that enabled the best fit to be assessed for the patient. He explained that intra-operatively, in selecting the size of the femoral stem component to be implanted, there are competing considerations that needed to be balanced. 91Amongst those considerations, were on the one hand, the importance of not undersizing the femoral stem because of the potential for inadequate mechanical interference fit, as a resultant inadequate stability could cause the implanted component to subside, and on the other hand, if the selected femoral stem was too large, this could create the potential for the femoral bone around the implant stem to fracture, which would then be a problematic complication. 92It was against that background that Dr O'Carrigan outlined the many sequential details of the pre-operative and intra-operative processes that he had undertaken for the planning, preparation, selection, sizing and the fitting of both the prosthetic acetabular cup size and the femoral stem. 93Those steps, which on a distilled analysis, appeared to be in 5 discernable stages, involved some 24, if not more, sequential skilled tasks, which I have summarised in the paragraphs that follow. 94First, as to planning and preparation for the operation: (1)Pre-operative AP or anterior posterior x-rays were displayed on an x-ray viewing box in the operating room; (2)Selected transparent overlay films were then placed over the displayed x-rays to allow estimates or judgments to be made as to what sized femoral and acetabular components were likely to be required. For that purpose, Dr O'Carrigan had available to him a kit of instruments comprising the entire range of sizes of the components within the Medacta system of prosthetic hip appliances. The unchallenged evidence indicated that the planning process was one of inexact estimation, not precise measurement. Templating alone, without the exercise of intra-operative judgment was not an accurate predictor of prosthesis size because of an inherent magnification factor in the ratio of 3:1 which had the potential to increase the scope for error; (3)Using the templating process, Dr O'Carrigan then made markings on the x-ray films to denote the position for the oblique cut that was required to perform femoral neck osteotomy. The following scanned extract from Exhibit "2", page 3, shows the oblique line that Dr O'Carrigan had marked on a radiographic film of the plaintiff's left hip to denote where he had planned to make the osteotomy cut in order to remove the femoral head of the plaintiff's left hip: [Arrow added] 95Secondly, the plaintiff was then prepared for the operation to proceed under anaesthesia: (4)After the plaintiff was draped and prepared for surgery on the operating table, both of her legs were placed in a traction boot device on the operating table in a manner that ensured that her pelvis was located squarely and in a position that permitted intra-operative x-rays to be taken if required; (5)Surgical exposure of the left hip was achieved through the muscle planes and related tissues to ensure that an adequate view was obtained of the structures to be manipulated and cut as required; (6)The next phase required that the acetabulum be prepared for the prosthetic implant to that area; 96Thirdly, the operation then continued with the removal of the diseased acetabular bone by using a grinding instrument, as follows: (7)After the acetabulum had been progressively reamed by an electric grinding ball that was sized in 1 or 2mm increments, the bone base or bed was then mechanically prepared for implanting the prosthetic acetabulum; (8)The acetabular component size was then trialled to identify an acceptable sized prosthetic component. When that size had been chosen, importantly, the actual acetabular implant was then fitted whilst feeling for the adequacy of the mechanical interface for fit, stability and grip into the underlying bone in the correct position; (9)In that manner, the plaintiff's acetabulum area was then fitted with a 52mm versafit uncemented hip cup inserted with ceramic neutral liner. After Dr O'Carrigan assessed the "feel" for the appropriateness of the size and the fit of the acetabular prosthesis, an intra-operative x-ray was taken with the image intensifier or mobile x-ray to check for adequacy of the location and position of the acetabular component to ensure that it reflected adequate anatomical restoration. In this way, the template and intra-operative x-ray served to confirm that the acetabular cup had been installed into the desired position, at the correct 45 degree angle that permitted adequate movement and stability of the prosthetic joint in all required directions using the opposing unaffected side as the comparative key or guide; (10)Once the preceding steps had been achieved, including ensuring that no impingement had occurred between the implanted device and the surrounding non-bony tissues as this might compromise the outcome, attention was then directed to the work required on the femoral head; 97Fourthly, the process then continued with the removal of the diseased femoral head and the preparation of the femur to receive the prosthetic femoral stem, as follows: (11)The preparation of the left femur then proceeded with reference back to the template and with visual identification of the location for the osteotomy cut for removal of the femoral head by reference to the anatomical landmarks of the greater and the lesser trochanter. The pre-operative AP x-ray was then marked for the position of the osteotomy cut. The lesser trochanter, whilst visible on the marked up scan, had to be identified by intra-operative feel. The osteotome was then used to make the required cut. Dr O'Carrigan stated that the location of the osteotomy cut in fact coincided with the proposed cut as marked on the scan; (12)Once the femoral osteotomy cut had been made, access had to be obtained to the proximal end of the cut femur to prepare the femur to accept the femoral stem. A series of progressively sized broaching instruments with roughened surfaces were then introduced into the canal of the femur to rasp an internal space in that bone in order to enlarge and achieve an adequate space to accept the prosthetic stem of the hip replacement device. Progressive in situ measurements of a number of femoral stem components were then trialled for size and for fit in order for Dr O'Carrigan to arrive at a concluded judgment as to the appropriate size of the femoral components to be used. This step involved a challenge in the case of the anterior surgical approach. Access was achieved by standing to the patient's left side, facing the head, and then obtaining extreme extension and external rotation of the femur with the aid of the traction device. This enabled the required angle of access for preparation of the femur; (13)The broaching of the femur commenced with size 0, it then progressed through to size 1, and then to size 2. For that process, Dr O'Carrigan had the entire range of size of broaching instruments and femoral stem implants available to him to meet all eventualities; (14)In this process it was necessary to release the soft tissues around the capsule of the left hip joint to avoid fracturing the femur by the exertion of the torsional forces that had to be applied to achieve this stage of the operation; (15)By this stage, an entry point into the canal of the femur had been created by using the series of graduated broaching tools to rasp and create and progressively develop a slightly curved canal space to accept the insertion of a femoral stem. This process was manual but was also guided by the pre-operative templating for stem size assessment. In this way an adequate femoral cavity was developed; (16)Once a range of prospective stem sizes were trialled, a decision was then made as to which sized femoral stem would achieve adequate mechanical stability in order to avoid migration of the device on weight bearing. This phase of the procedure required Dr O'Carrigan to make a surgical judgment that involved a choice between the larger size, which might cause femoral fracture in the process of seating the device into place, or too small a size, which might not achieve adequate mechanical stability on weight bearing. In this phase, Dr O'Carrigan had to rely on his manual "feel" of the placement of the device whilst trialling the prospective sizes in situ. That was the final determining factor for completion of the size selection process; (17)During the trialling process, by means of manual manipulation within the limitations imposed by the chosen anterior surgical approach, the plaintiff's hip was put through a range of motion to ensure that it did not impinge with other tissues. Dr O'Carrigan also had to ensure the device was stable; (18)In the trialling of the femoral stem component using the anterior approach, including the range of movement testing by using shucking manoeuvres, Dr O'Carrigan had to look to achieve the appropriate degree of soft tissue tension. This also required that he obtain or assess a "feel" for whether the device chosen was appropriate. With the anterior operative approach, soft tissue tension was more difficult to gauge, and for that reason, the intra-operative traction device had to be released to enable some range of movement testing manoeuvres to take place; (19)By the above process, after trialling a number of combinations of sizes of the 3 components of the femoral prosthesis, Dr O'Carrigan decided upon a size 2 femoral stem with a standard neck with a 32mm head in a short configuration. The choice of sizes of those components was governed by the process of pre-operative templating to estimate stem length and required offset, and the intra-operative trialling of those component sizes in situ, as described above; (20)At that stage, once the decision on sizing was made, the trial components were removed, the area was then lavaged and the selected femoral stem component was manually inserted into the femoral canal to a point above the osteotomy cut, following which the inserted stem was impacted with some effort by force applied with a mallet until it became embedded to the determined level of femoral stem insertion without fracturing the femur, about a centimetre or so above the level of the osteotomy cut. At that stage, stability of fit was a critical factor because, with the Medacta system used, the fitting process did not involve the use of cement for fixation; 98Fifthly, the procedure was then completed as follows: (21)The completion phase of the procedure required that the prosthetic components be assembled in apposition. This required the application of the range of motion tests or shucking, and then obtaining an intra-operative x-ray using the image intensifier or mobile x-ray device to assess positioning, alignment and length; (22)Once satisfied that the procedure had been completed according to plan, Dr O'Carrigan repositioned and repaired the capsule and the related soft tissues, the surgical wound was closed, and the patient was sent for post-operative recovery; (23)The unifying goal of the above testing by those various means was to check that the positioning of the prosthetic components was in accordance with what had been planned by the pre-operative templating, and at the same time ensuring appropriate soft tissue tension and stability of the joint, as well as identifying any periprosthetic fractures, if present; (24)In the above process, it is important to observe that the post-operative x-ray testing for positioning of the prosthetic components was not an accurate method of measuring leg length because it was a test aimed at detecting malpositioning of components, if present. 99After the operation, Dr O'Carrigan next saw the plaintiff in the recovery section, as was described by the plaintiff. Dr O'Carrigan's post-operative instructions were for intravenous antibiotics, the insertion of a surgical drain for 24 hours, and for mobilisation and weight bearing as tolerated. 100After setting out the events of the plaintiff's post-operative course, I shall return to the evidence of Dr O'Carrigan in which he explained the plaintiff's leg length discrepancy as a function of intra-operative error.

Post-operative course following first procedure 101The plaintiff did not have a detailed recall of the daily sequences of events involving her post-operative recovery. The chronological detail of those events comes from the plaintiff's limited recollection and from hospital clinical notes, and this was annotated by commentary from within the evidence of Dr O'Carrigan where appropriate. 102Following the first procedure, the plaintiff recalled being in the post-operative recovery section of the hospital and she recalled Dr O'Carrigan telling her that the operation went well. Whilst in recovery she was aware of being unable to move her left leg and she was aware of terrible pain in her left groin. She recalled Dr O'Carrigan expressing concern over this, and she recalled asking him whether he could move the position of her leg, and she recalled him responding that he could not do so at that time. 103Dr O'Carrigan explained that in view of the plaintiff's complaints, a post-operative x-ray of the left hip was then taken in recovery using a mobile x-ray device: Exhibit "2", p 4. This x-ray was arranged because of the plaintiff's complaint of groin pain. The practical purpose of that x-ray was to undertake a gross check in order to confirm the correct location of the hip prosthesis and to determine whether there were any major complications, such as malpositioning of the prosthesis or periprosthetic fractures. There were no such complications evident on that x-ray. 104The following scanned extract from Exhibit "2", p 4 shows part of the x-ray image of the plaintiff's left hip taken in post-operative recovery with the prosthesis in place as described above: 105Dr O'Carrigan explained that as can be seen from the above image, the nature of that x-ray did not permit fine judgments to be made concerning leg length discrepancy due to the quality of the relatively poor x-ray as it was necessarily taken in less than ideal circumstances: T98.18 - T98.27. The purpose of the x-ray was to essentially check the position of the prosthetic components. The nature and quality of that x-ray meant that it was not capable of being used to check for post-operative leg length as the detection tolerance was more in terms of centimetres rather than millimetres. 106After that x-ray was taken, and before leaving the hospital that evening, Dr O'Carrigan waited for the result to ensure that there was no immediate problem such as malposition or neurovascular complication that could explain the plaintiff's complaint of groin pain. Dr O'Carrigan also made sure that the gross neurological function of the plaintiff's left leg was intact, meaning she had reflexes and she could move her left ankle and toes. He also personally checked the x-ray. 107The plaintiff's next memory after being in the post-operative recovery section is of waking in her allocated hospital room, with patient controlled analgesia in place ("PCA"), which lasted for 24 hours. She recalled that her severe left groin pain had lessened in intensity. Subsequently, in the ensuing days, once she had started to weight bear on her left leg, she noticed pain in her left groin. 108The Hospital notes show that Dr O'Carrigan conducted three post-operative reviews of the plaintiff's condition. 109At the first post-operative review, on 3 August 2011, Dr O'Carrigan assessed the plaintiff as doing well. He gave instructions for the plaintiff to sit out of bed and to attempt mobilisation on that day if possible, and to remove the post-operative drain and PCA analgesia the next day. 110At the second post-operative review, on 4 August 2011, Dr O'Carrigan gave instructions to remove the drain, to mobilise as soon as possible, and for rehabilitation if necessary. 111On 4 August 2011 the plaintiff developed unrelated palpitations or supraventricular tachycardia ("SVT"). This was managed by hospital staff through discussion with the plaintiff's cardiologist, Dr Day, and that condition settled. The plaintiff developed coincidental gastrointestinal problems which also settled. Those matters had no relevance to the issues in this case. 112At the third post-operative review, on 8 August 2011, Dr O'Carrigan saw the plaintiff and gave instructions for her to be discharged when she was confident with ambulating and when the physiotherapist was happy to discharge her. 113At that time, Dr O'Carrigan made a note in the hospital records to state that the plaintiff was feeling better, her SVT had settled, and that she felt no pain. That entry in the records was also made in the context of a note made by Dr O'Carrigan that the plaintiff felt her left leg was slightly longer. 114In the plaintiff's account of her conversation with Dr O'Carrigan on the day of her discharge she stated that he had asked her how she was feeling. In response, she told him she felt like she was lopsided and tipping on one side. The plaintiff said there was no discussion about leg length. She said she just thought all was normal and as she had not had a previous hip replacement she was not sure how she was supposed to be feeling at that time. 115Given the plaintiff's reference to a feeling of lopsidedness and the content of Dr O'Carrigan's note, I find that there must have been a discussion that included the subject of leg lengthening, although the plaintiff may not have used that term. 116The plaintiff stated that when she had told Dr O'Carrigan that she felt lopsided, her perception of his facial expression was that it changed to what appeared to her to be one of apparent shock. In my view, no liability conclusions can be drawn from the evidence of the plaintiff's subjective perception of Dr O'Carrigan's changed facial expression. Her account of the ensuing conversation with him about her feeling of lopsidedness was that he advised her she would have to wait for the healing process to take its course. She had an appointment to see Dr O'Carrigan for a post-operative review at 6 weeks, on 15 September 2011. 117Dr O'Carrigan explained that whilst he could not recall the precise words he used when he spoke with the plaintiff whilst at the hospital, he confirmed that he had a conversation with her to the effect that it was not uncommon for patients to feel a difference in leg lengths at that time, and that this could settle, and that time would have to pass to see whether or not this would settle. In his evidence he explained that following such a procedure a 6-week post-operative review was a standard interval of time for a scheduled review, particularly in respect of leg length, as that period allowed adequate time to pass for a perception of leg length discrepancy to settle, if that was going to occur. 118Dr O'Carrigan also explained that an earlier surgical revision was contra-indicated as it increased the risk of infection due to incomplete wound healing and possible colonisation by bacteria, as well as an increased risk of deep venous thrombosis and pulmonary embolus. He explained that those were relevant considerations in the plaintiff's case because she had an episode of tachycardia during her stay in hospital. He also stated that in the circumstances, revisionary surgery would not have been offered without a clearance on that issue, and only after appropriate investigations had taken place. 119Whilst the plaintiff was still at the hospital on 8 August 2011, before her discharge, but after Dr O'Carrigan had seen her, a hospital physiotherapist had noted on post-operative Day 6, that the plaintiff reported some pulling sensation in her left groin, but was otherwise well. The physiotherapist noted the plaintiff was able to mobilise with crutches, including on stairs and bed transfers, and was therefore considered safe for discharge home. 120The plaintiff was discharged from hospital on 8 August 2011 and was ambulating with the assistance of crutches. Over the course of the ensuing 5 to 6 weeks she graduated from using two crutches to using one, and then to using a walking stick. During this time, she was experiencing various different sensations. She stated she was feeling cold, shivery, and felt that lots of uncertain things were happening at that time. She was also having physiotherapy and she remained off work.

Dr O'Carrigan's explanation of error in first procedure 121Dr O'Carrigan explained that the error of the type that occurred in the plaintiff's first procedure was a complication that rarely occurred in his practice, and one that he has made only infrequently: T137.30 - T137.35. He agreed that this type of error is one that is generally avoided by close observance of the checking procedures starting from templating, through to clinical examination, and before completion of the operation: T137.39. 122When pressed on the issue, Dr O'Carrigan freely acknowledged that despite the measures incorporated within the 5 stages of intra-operative checks referred to in the evidence, he nevertheless made an error with stem selection: T130.31. He also stated that although he aimed to take extreme care in all cases, despite the 5 levels of intra-operative checks, the fact remains that the results of surgery can sometimes fall short of expectation: T144.19 - T144.36. 123In his retrospective analysis, Dr O'Carrigan ultimately thought that the error in question was likely to have occurred at the point in time when he decided to go from the trial prosthesis to the implantation of the actual prosthesis: T152.34. He further explained that he broached the femoral canal up to size 1, and then felt that it was not quite tight enough and he then broached it to size 2 in order to obtain the correct tightness to ensure adequate mechanical interference for stability of the implant: T152.35 - T152.42. That decision which was a judgment call that Dr O'Carrigan made during the operation, not in the templating phase. He said that the described process was not foolproof, which I took to mean it did not eliminate the scope for error: T152.47. 124Dr O'Carrigan explained that even after taking the required precautions, there were limitations on the accuracy of the procedure. His evidence on that topic in relation to the occurrence of error was at T122.12 - T122.21, and was in the following terms: "Q. Having done all those things, how is it that the leg length did achieve something in the nature of 2 to 3 centimetres in functional leg length? A. Because I made an error. I made an error. Q. Can you identify where that error lay? A. It lay in the balance between undersizing and getting a tight fit and mechanical interference fit and the judgment on that day at that time at that point in time in theatre that I felt that a size 1 was undersize and that a size 2 was a better fit. Taking all those factors into account, that's a decision that I made at that point in time and I now know that that was wrong." [Emphasis added] 125In cross-examination, Dr O'Carrigan was pressed to explain why he had selected the wrong sized stem. His evidence in that regard, at T146.30 - T146.50, was as follows: "Q. Doctor, the number 2 stem inserted on 2 August 2011 to the very best of your ability was nonetheless the wrong stem, wasn't it? A. Yes, it was. Q. Doctor, what I'm trying to elicit from you is why you chose the wrong stem? What went wrong? A. I chose the stem at the time, at that point in time in theatre, that I thought was the correct size for the patient. I did it in good faith with all the information that I had in hand. That was my judgment at that time. Time has proven that to be incorrect. I recognise that, I corrected the problem. Q. We know the process by which you corrected it at the surgery on 23 September, but what I'm asking you about is how you came to choose the wrong prosthesis on 2 August? What's the lesson that you're taking home from this case? A. The lesson that I'm taking home from this case is that every patient that I treat, every operation that I do, every decision that I make has potential for significant consequences for both the patient and myself and every decision has to be made with care. I have done that to this point and I will continue to do so." 126Dr O'Carrigan explained that the system of templating he used to plan for the sizing of the prosthetic components did not prevent or entirely eliminate the scope for error to occur: T129.49 - T130.2. He also explained that the system of intra-operative checks employed for the procedure was designed to reduce or minimise the risk, but nevertheless, it was not a failsafe system for the prevention of error: T130.12. 127The intra-operative checks to which he referred, essentially involved 5 steps. These comprised first, the results of the initial clinical examination, secondly, templating to assist in determining the size of the prosthetic components required for the procedure, thirdly, employing a series of trial devices to assist in determining the size of the final component to be used, fourthly, the use of an image intensifier or mobile x-ray to assist in determining correct positioning of the prosthetic components once they had been placed into position including to exclude periprosthetic fractures, and fifthly, the products of his final clinical examination before completing the operation: T130.4 - T130.28. 128Dr O'Carrigan said that he had observed those required intra-operative checks. He said that nothing had gone wrong in the templating process: T145.34. He also said that both the size 1 and the size 2 stem prostheses were an appropriate fit, the difference between the two sizes being what he considered to have been the correct location of the prosthesis within the femur: T145.45; T146.5. The image intensifier x-rays were interpreted as showing that the prosthesis was appropriately located in the correct position: T146.10. He also said that his clinical examination of the implant was his "feel" for the correct position and tissue tension: T89.20; T97.47. 129It is clear from the evidence that the checks described above, each involved the need for Dr O'Carrigan to make a series of intra-operative judgments based on his training, knowledge and experience in light of the clinical circumstances that were before him. 130Dr O'Carrigan explained some of the detail of the procedure involved in the first operation including the intra-operative checks, as well as the pre-operative preparation that he had undertaken beforehand. 131Dr O'Carrigan gave consideration to what must have gone wrong during that procedure after he had reflected on the adverse result that was obtained. In that process, he was in effect, reviewing the intra-operative judgments he had made on the day. 132Significantly, in his evidence on those matters, Dr O'Carrigan's explanations on matters of clinical judgment remained uncontradicted by other factual evidence. Accordingly, in the absence of challenges on matters of fact or credit, unless the detail within those explanations appears inherently improbable, which they do not, they should be taken to represent a correct factual account of the key events that occurred during the first operation. 133A possible inference arising from the evidence is that for whatever reason, one or more of the intra-operative checks for stem size, position and fit, had not been carried out, or had perhaps been carried out incorrectly. Although a consideration along those lines was open on a first level of analysis, on the evidence as a whole, such a conclusion was entirely speculative and without factual foundation in circumstances where there was nothing in the evidence given by Dr O'Carrigan that acknowledged the force of such a proposition, and there was no other evidence from experts that supported the proposition that there had been a departure from the expected standard of care. 134Dr O'Carrigan's evidence in relation to the first procedure was challenged in a number of respects. Those challenges, and his responses, are summarised as follows: (a)whether he had made the wrong choice of prosthesis, which he said to his knowledge, he had not: T147.13; T152.30; (b)whether it was possible that an error occurred in the templating process, thereby resulting in an inappropriate choice of a size 2 stem over a size 1 stem, to which he fairly replied that it was possible: T148.15. That answer did not constitute an admission of the proposition that was put; (c)whether he would have achieved the same result if he had inserted the stem into the femur more deeply, to which he replied that if he had done that, he may have fractured the plaintiff's femur: T147.48 - T149.1; (d)whether he had inserted the size 2 stem in the femur as far as he did because of fear of fracture, or whether the point of maximal insertion was as far as he thought it needed to be inserted, to which he replied that he had inserted it to the point where he thought it was a good fit and reproduced the plaintiff's anatomy: T148.3 - T148.6; (e)whether if, he had inserted the size 2 stem a further centimetre down into the femur, he would have achieved the right result, to which he replied that he could well have, but in the process he may have also fractured the femur: T148.8 - T148.22; (f)whether if, during the course of the procedure, he considered that the inserted stem may not have achieved the desired result, he could have removed the size 2 stem and replaced it with a size 1 stem, to which he replied that if that would have been his assessment at the time, he would not have hesitated to have removed a wrong sized stem, as he would not have deliberately left an incorrectly placed implant in situ, thereby leading to a complication which could have been corrected whilst the plaintiff was still in the operating theatre: T148.24 - T148.42; (g)whether, if he had taken more care in the procedure he could have (as distinct from would have) avoided the complication in question: T138.13 - T138.18. That answer was not further developed or explored by follow-up questions; (h)whether he had checked for leg length discrepancy at the end of the first procedure, which he said he did that at that stage whilst the plaintiff was on the bed when she was transferred to recovery, and that a leg length discrepancy was not clinically apparent at that stage: T156.45 - T152.48; (i)whether the reason he did not order post-operative x-rays on 8 August 2011, when the plaintiff made reference to lopsidedness or leg length discrepancy, because at that stage he already knew that he had probably chosen the wrong prosthesis, to which he replied he did not know that at that time: T164.4 - T64.10; (j)whether there was any reason why the size 1 stem used on the second procedure could not have been used in the first procedure (as propounded by Dr Bracken), to which he responded that the proposition was more complex than the terms in which it was put, in that the shortened femoral neck used on the second occasion was because the angle of offset changed, so that when he changed from a size 2 to a size 1 stem in the remedial procedure, the shortened femoral neck used in the second procedure served to maintain the angle of offset so as to achieve shortening. He went on to say it was not as simple as stating "its just a shorter neck": T122.36 - T123.38. There was no expert evidence which contradicted that answer; (k)whether he had an explanation as to how he had done so many such operations and "got all those cases right" and "got this one wrong", to which he responded that he did not have an explanation: T147.22. 135In respect of that last answer, at T147.24 - T147.36, the following exchange occurred between Dr O'Carrigan and the cross-examiner: "Q. And so as far as you're concerned, it's just one of those things, is it? A. It's not as simple as that because it's not just one of those things. "Q. No. It can't be, can it. This is a scientific process, isn't it? A. It's not a fool proof process. We make it as scientific as we can, but it is still not an absolute you cannot undertake that process with absolute certainty that every correct decision is going to be made at that point in time. You can't eliminate the risk. I talk to patients about, when I try to describe risk, I say that you can go to a set of lights to cross the road, you can wait for the lights to change and the green indicator to come up, you can check the traffic on either side, then you can cross the road within the pedestrian crossing and still be run over by somebody who runs that red light unexpectedly. You cannot eliminate risk." 136When Dr O'Carrigan was further questioned about where he thought the error lay in the first procedure, on reflection he said it was in his decision to insert the size 2 stem in the position in which he had inserted it in the femur at the time of the operation: T147.45 - T147.47. 137Dr O'Carrigan was asked whether he had ever explained his error to the plaintiff. His evidence on that matter, at T139.1 - T139.4, was in the following terms: "Q. Dr O'Carrigan, did you ever have the opportunity of explaining to Ms Lange the nature of the error which you now acknowledge? A. Yes, I did. On the three phone calls I made on the 20th and the extensive consultation I had with her in the presence of family on the 23rd." 138In giving that evidence, he acknowledged that he did not recall using the specific words of having chosen the wrong sized stem: T139.28 - T139.40. In the absence of an assertion of recent invention, that answer should not be considered to be damaging to Dr O'Carrigan's credit as a witness. 139In cross-examination, at T130.30 - T130.41, Dr O'Carrigan was questioned as to whether he felt that there was a particular point during the procedure where he felt he had missed a sign. He was also asked if he felt he could have carried out the pre-operative templating more carefully. His evidence was as follows: "Q. Despite those five measures, you've nonetheless made this error? A. I have. Q. Is there any particular point where you feel you missed a sign? HIS HONOUR: Meaning hindsight? ELLIOTT Q. Could you have done the templating more carefully? Could you have paused for more thought about the selection of the device? What do you put that error down to, doctor? ..." 140By way of further answer to the above questions, at T131.6 - T131.46, Dr O'Carrigan gave the following evidence: "... A. I made a decision that I thought was the correct one at the time on the evidence that I had and in retrospect it turns out to be incorrect and I've made many, many other similar decision at similar points in time and got it correct. It's not the only error that I've ever made and it is not the last one. Q. I think what Mr Elliott was seeking from you, if you can answer this question, looking back on the events of the initial procedure and looking forward prospectively as you went through it, can you identify a moment where this error crept in? A. There's through the anterior approach that issue of soft tissue tension is not as easily accessible as it is through a posterior approach. And whilst that comes down to feel and you cannot quantify it, it actually is a very important thing because when you put in a hip tight you can feel it's tight. You don't have to get an X ray, you don't have to go through other factors. You know, you can do checks but you know that it's tight. And whilst the leg is in traction you can release the traction, which we did, you can try to get a feel of the tension. It's not as good a feedback as it is through a posterior approach and if I had to put it down to what was the biggest factor that maybe influenced making that decision on that day, that was probably it. But it's important to understand for the Court that every approach has some advantages and disadvantages, and there's some things are easier and there's some things that are harder, there are some things that can contribute to this aspect of it but, you know make other aspects easier. So it's all a balance of pros and cons, risk versus benefits and you are taking all these factors into account doing a procedure. So there is no perfect approach, there is no perfect surgeon, there is no perfect patient, there is no perfect system. Q. I suppose on that paradigm you could also throw in the individual differences of tissue reaction too I suppose? A. And that is why, that's a very important point because there are some people, and this has not come out in the evidence to point, but there are some people that you could lengthen one centimetre and they would adjust. They would stretch out. Their pelvis would level off, they would not have pain, they would not have problems. Just as there are some people who can be Olympic gymnasts and there are some people who can't touch their toes. There's variations in the flexibility of people's soft tissues, so therefore their ability to accommodate a leg length discrepancy varies. Their ability to for the soft tissues to tension and lengthen out varies and unfortunately with Kelly, the leg length discrepancy that we created was just enough to tip her over into that decompensation level so that she developed contractures which made her leg length difference greater." 141It is clear from the above series of answers, that to succeed in this case, the plaintiff had to call evidence to impugn Dr O'Carrigan's clinical judgment and show that it was foreseeably and avoidably wrong at the time he made those judgments. 142On the central issue of whether Dr O'Carrigan could have avoided the complication of leg lengthening in the plaintiff's case if he had taken more care, in his evidence at T138.13 - T138.18, the following exchange occurred: "Q. Doctor, if you had taken more care you could have avoided this injury, couldn't you, this complication, couldn't you? A. I treated Kelly the way that I treat every patient that comes through my practice, with the same level of care. But on that day, I made a judgment between size 1, size 2, I made an error, I recognise that error, I corrected the error." 143Although the above answer incorporated a conflation of events between the plaintiff's communication of leg length discrepancy on 8 August 2011 and the revision procedure on 23 September 2011, significantly, there was no concession by Dr O'Carrigan to the effect that he had the opportunity to recognise and to avoid the error before completing the first operation. 144Dr O'Carrigan's evidence as highlighted and summarised in the preceding paragraphs, which involved judgments he had made on the day, was not contradicted by other evidence and it was not otherwise inherently improbable. 145In the lead-up to the trial there was no attempt on behalf of the plaintiff to seek to interrogate Dr O'Carrigan on matters in issue. None of the criticisms advanced by the experts called on behalf of the plaintiff identified an actual sentinel moment in the course of the first procedure when a foreseeable and avoidable error occurred. 146Instead, the case for the plaintiff relied upon the drawing of inferences concerning matters that Dr O'Carrigan ought to have recognised intra-operatively, and which he had later recognised as an error, and that he should have rectified such error on 2 August 2011, so as to obviate the need for re-operation. 147Those propositions will be explored in the course of setting out my reasons for consideration of the principal issue to be determined in the proceedings, namely whether Dr O'Carrigan has been shown to have been negligent in the performance of the first procedure.

Events between discharge and 6 week review 148On 6 September 2011, whilst on a holiday break in Forster, NSW, and following a long and uncomfortable drive in which she was a passenger, the plaintiff needed to attend a local medical centre with concerns about a bruise-like blotch that had developed on her left thigh, as well as pain in her left hip, groin and thigh. She was also experiencing pain and difficulty sitting. She was taking an anti-depressant for neuropathic pain. She was prescribed antibiotics: Exhibit "8". She already had a scheduled appointment with Dr O'Carrigan in the following week. 149Before the plaintiff saw Dr O'Carrigan for the scheduled 6-week post-operative review, she had been continuing to undergo physiotherapy, and had been compliant with the physiotherapist's directions. She had also been experiencing what she thought was some loss of circulation of her left leg, and she thought that her muscles were not contracting properly when she was stretching. 150On 15 September 2011, Dr Day had incidentally written to Dr O'Carrigan to report on his follow-up of the plaintiff's earlier experience of paroxysmal atrial tachycardia. In that letter he noted that the plaintiff was upset by her slow recovery from the hip replacement surgery that had been carried out 6 weeks earlier.

Post-operative consultations at 6 weeks and following 151The plaintiff stated that when she saw Dr O'Carrigan at the scheduled 6-week post-operative consultation on 15 September 2011, she had informed him of the matters described above. She said he had sent her to have x-rays performed on her left hip and he then saw her again later that day in his rooms, following which he advised her to go home and continue to live her life as she normally would. 152In the days that followed Dr O'Carrigan's 6-week review, the plaintiff contacted her general practitioner. After some follow-up calls asking for him to obtain the report on her recent x-ray, she attended a consultation with that general practitioner at which time he read to her from the report. He told her that the x-ray report indicated she had a 2.8cm leg [length] discrepancy, that her pelvis was tilted, and that her soft tissues and muscles were not functioning properly. The plaintiff said her reaction to this news was one of shock. 153On 18 (sic for 15) September 2011, Dr O'Carrigan ordered an erect x-ray of the plaintiff's pelvis, the hips and legs to the ankles on the one film: Exhibit "B", p 80. The date appears to have been erroneously recorded in the x-ray order form as the resultant x-ray report was dated 15 September 2011: Exhibit "B", p 82. The x-ray report by Dr Luckey stated: "XRAY PELVIS AND BOTH LEGS The right hip outlines normally without signs of degeneration or inflammatory arthritis. No obvious signs of AVN are seen. Left sided THR is noted. There is a satisfactory alignment of the implanted non-cemented prosthesis. There is moderate pelvic tilt. No significant degeneration of the femorotibial joint is noted on either side. A leg length difference of 2.8cm in favour of the left leg is seen." 154In his oral evidence, Dr O'Carrigan stated that he disagreed with the accuracy of the post-operative radiological measurement of 2.8cm leg length difference. He considered the true leg length difference to be either 1.1cm or approaching 1.8cm. 155Dr O'Carrigan explained that he had arrived at his own estimates by taking measurements from recognised landmarks. He explained that Dr Luckey's measurement of 2.8cm had been influenced by a tilting of the pelvis which was evident on the x-ray and should therefore not be taken to be the true leg length discrepancy. 156Dr O'Carrigan explained that the image in question demonstrated the pelvic tilt as well as showing the difficulty in making accurate measurements because the appearances of the normal hip on the plaintiff's right side and the left sided prosthesis had no equivalent landmarks for comparison, which was why specialised measurements were required, and which he later carried out on the x-rays, including by using a known conversion formula applied to the grid, as is evident on some of the images which are part of Exhibit "2". By those means Dr O'Carrigan identified the leg length discrepancy as being 1.1cm. 157Dr O'Carrigan explained that such measurements were best undertaken in quiet time when on his own in the absence of time pressures when he could make the necessary study and identify appropriate landmarks for making measurements. His evidence in that regard at T104.10 - T104.15 was not challenged: "... A. It's something I would normally do quietly on my own because especially in this particular circumstance, because it was a very, very important decision that had to be made, and it was very important that I make it as accurate an assessment as possible, as to what the extent of the leg length discrepancy was and what the possible cause of it was." 158On 20 September 2011, after undertaking his leg length discrepancy analysis in which he identified the discrepancy as being 1.1cm, Dr O'Carrigan wrote to the plaintiff's general practitioner in the following terms: "... Kelly had her left Total Hip Replacement on 2nd of August 2011 through an anterior approach. She had some issues with groin adductor pain in the early postoperative phase but that has largely settled and she has good pain relief but she feels her leg is probably longer. Clinically her left leg is longer. She tends to stand with the left knee slightly flexed to compensate. Erect leg x-rays were taken to show the hips knees and ankles on one film so an accurate assessment of the leg lengths could be undertaken. The left leg is 1.1 cm longer than the right when one measures the two femur lengths and tibial lengths separately then compares that to the length of the leg as a whole from tip of the femoral head to the ankle. This is despite careful preoperative templating and intraoperative x-ray. The options are operative and non-operative. Kelly could wear a shoe raise on the right side. This would be permanent. We can revise the left hip replacement. The Medacta hip does not have a modular neck and we used the shortest head available so to shorten the leg 1 cm we would need to remove the prosthesis and reinsert a new prosthesis lower down the femur. The medacta is a fully HA coated prosthesis and at 7 weeks post-op now there would be early healing and ingrowth so removal may not be easy. I will ring Kelly to discuss this. I will keep you informed of her progress. ..." 159The plaintiff stated that on the following Monday, 19 September 2011, she then rang Dr O'Carrigan's rooms in order to discuss those matters with him. She said that Dr O'Carrigan rang her back on the following day, 20 September 2011. The plaintiff gave a vague account of that conversation. She recounted that there was some mention of there being problems and of her needing to wear a prosthetic shoe. She stated that in that conversation, Dr O'Carrigan had told her he was in between surgeries at that time, and that he would ring her again later. 160Later that day, Dr O'Carrigan rang the plaintiff as he had promised. Her account of that conversation was that he had told her she had no choice but to undergo another operation otherwise she would have too many ongoing problems. She said he had told her "it was already 7 weeks too late". It appears from Dr O'Carrigan's explanation of the contraindication for earlier revisionary surgery, that the plaintiff's account of "7 weeks too late" may have been a conflated account, although I am in no doubt that she honestly believed he had said words to that effect. 161In giving the gist of the above conversations, the plaintiff indicated that whereas in the first conversation he gave her the impression that there was some element of choice as to whether she could wear a special built-up shoe or have further surgery, in the second conversation her impression was that there was no element of choice conveyed, and that she understood that further surgery at that time was the only option. 162The plaintiff then made an arrangement to see Dr O'Carrigan in his rooms on Friday 23 September 2011. On that occasion, her partner, her daughter and her parents were also in attendance. At that consultation, Dr O'Carrigan discussed the prospect of the plaintiff having a re-operation on her left hip later on that same day. 163In the events surrounding that consultation, Dr O'Carrigan revised his calculation of the probable true leg length discrepancy to something approaching 1.8cm. In evidence, he explained that pre-operatively, without a hip calibrator, which could only be used during a posterior operation, the measurement process did not involve precision. 164On 23 September 2011, Dr O'Carrigan wrote to the plaintiff's treating general practitioner in the following terms: "... Kelly probably has a true leg length discrepancy approaching 1.8cm based on erect leg x-rays and measurements from the teardrop to the femoral joint line. Her functional leg length is greater than that because of soft tissue contracture and pelvic tilting and she is getting significant symptoms and we need to revise her to shorten the left leg and we are going to revise the total hip replacement today at Sydney Southwest Private Hospital. It is time dependent how long we leave this because the longer the hip is in the greater the bony ingrowth and it becomes more difficult to remove the component. I have gone through the operation with Kelly and her family today in detail and we will proceed with the surgery this evening. We are going to try to do it through an anterior approach but if that is not successful we will need to close that and perform the revision through a posterior approach and possibly do a femoral osteotomy. I will keep you informed of Kelly's progress. ..." 165Dr O'Carrigan explained that the methodology for estimating leg length discrepancy was not standardised. He explained that each surgeon had their own developed methods for estimating such discrepancies. In that regard he noted that estimates based on x-rays, even when using a measurement grid, were not entirely accurate: T132-T133. The most accurate measurement of true leg length discrepancy was the intra-operative measurement, which later turned out to be a 1cm discrepancy: T133.9.

Dr O'Carrigan's decision to re-operate 166As was the case with the first procedure, the conversation between the plaintiff and Dr O'Carrigan on 23 September 2011 was the basis for a patient information form completed by Dr O'Carrigan. That form recorded a diagnosis of leg length discrepancy requiring treatment by shortening of the affected leg by 1.8cm. 167An alternative non-operative option was identified as a watch and wait approach, noting that without the suggested treatment, the natural history of leg length discrepancy would be for ongoing and worsening problems. The plaintiff signed that consent form on 23 September 2011, thereby agreeing to the second procedure. 168The plaintiff said that on this occasion, there was some discussion on which approach would be used in the revision surgery. She had apparently expressed a preference for the remedial surgery that did not involve going through an anterior approach, as she preferred not to have more scar tissue and damage to the front of her leg. Whether or not this request could be observed depended upon the intra-operative clinical circumstances that prevailed during the operation. That was a clinical matter for Dr O'Carrigan to determine during the operation. 169The plaintiff stated that Dr O'Carrigan informed her there were 3 options, Option A being the anterior approach, Option B being the posterior approach, and Option C being the need for an osteotomy to cut away some of the femoral bone surrounding the stem if difficulties were encountered in removing the femoral prosthesis due to bony ingrowth, the expected process by which the prosthesis would become fixed and secure over time because of its hydroxyapatite properties that created bonding of the prosthesis to bone. 170Dr O'Carrigan's evidence on these events will be reviewed in connection with my findings related to the timing and indication of the second procedure.

Second operation - Intra-operative events 171On the evening of 23 September 2011 the plaintiff was admitted to the Sydney South West Private Hospital for revision of her left total hip replacement to be performed by Dr O'Carrigan. The procedure took approximately 5.5 hours: Exhibit "B", p 111. 172In that second operation, Dr O'Carrigan first attempted an anterior approach through the previous incision. In this procedure he identified the true leg length discrepancy to be 1cm. After dislocating the left hip joint, this attempt to remove the femoral stem proved unsuccessful. The wound was then repaired in layers. The plaintiff was then placed into a lateral position on the operating table in order to permit a posterior approach, which was successful in removing the femoral stem. The removed stem was then replaced with a size 1 Medacta short neck lateral offset stem with a 32mm short ceramic head, which was different to the standard neck used in the first operation. 173This procedure achieved the intended remedial 1cm shortening of the left leg and a stable hip was also achieved. Appropriate soft tissue tension was then established and the posterior wound was repaired in layers. The plaintiff was then sent for post-operative recovery with a surgical drain in situ. That drain was removed on 25 September 2011. 174In his operation report dated 23 September 2011, in addition to relating the above details, Dr O'Carrigan stated that in the second procedure he had achieved direct femur shortening of a measured 1cm, and he had implanted the femoral component more distally in the course of that procedure. 175The second procedure had involved more than the anticipated surgical time due to the need for Dr O'Carrigan to change his surgical approach during that procedure. Nothing turns on this fact. 176The hospital progress notes made after the second surgery record that the plaintiff was emotional about having had the revision surgery. 177Dr O'Carrigan saw the plaintiff on 2 occasions in hospital following the second operation. 178On his first in-hospital post-operative review following the second procedure, on 24 September 2011, Dr O'Carrigan wrote in the hospital notes that the plaintiff had no pain and there was minimal drainage. He ordered all drains, catheters and PCA to be removed on the following day. He wrote that he had spoken to the plaintiff at length and in detail about the operation. He planned to review her the next day before going on leave for 2 weeks. He had arranged for a colleague, Dr R Walker to supervise the plaintiff's care whilst he was away. 179On his second in-hospital post-operative review following the second procedure, later on 24 September 2011, Dr O'Carrigan again ordered removal of the PCA, catheter and drains. He ordered some blood tests with a view to a possible need for a blood transfusion, but ultimately this was not required. He ordered mobilisation. 180On 27 September 2011, in hospital, Dr Walker saw the plaintiff in lieu of Dr O'Carrigan and noted she was mobilising well, and that her leg lengths felt better. He ordered continuation of antibiotics. 181On 29 September 2011, in hospital, Dr Walker saw the plaintiff again and noted that her wound was satisfactory. He noted that follow-up arrangements had been made for the plaintiff to see Dr O'Carrigan and he cleared the plaintiff for discharge home. She was then discharged from hospital on that date.

Dr O'Carrigan's explanation for timing of second procedure 182Dr O'Carrigan stated that the 6-week post-operative appointment for him to review the plaintiff was a standard post-operative review time as it allowed for an adequate period of time to pass for patient perception of leg length to settle, if it was going to do so: T99.36. 183In his evidence in chief, Dr O'Carrigan stated that he had based his decision to re-operate 6 weeks after the first operation on the following factors: (a)the plaintiff's history of worsening pain and distress, and her feeling that her left leg was longer than her right leg: T102.34; (b)the plaintiff appeared anxious and upset, which indicated to him that she was not adjusting well to her obvious leg length discrepancy: T102.43 - T103.1; (c)the plaintiff's left leg appeared to be significantly longer on clinical examination of the order of 2cm or more, which surprised him (T103.24) and which then led him to undertake more precise attempts at measuring the discrepancy which resulted in an approximation of 1.1cm: T104.26; (d)the plaintiff was displaying significant pelvic tilting secondary to soft tissue tightness and contracture: T104.30 - T104.38; (e)he weighed the operative and non-operative management options, these being life long use of a shoe raise as opposed to a re-operation: T107.16; (f)he thought that waiting longer than 6 weeks to re-operate would have a big influence on difficulty removing the femoral stem at a later stage as further bony ongrowth would have occurred, which would have risked greater complications involving osteotomy to split the femur, and the risk of greater soft tissue dissection, more blood loss, and greater scope for complications: T107.43 - T108.5; (g)at the 6-week stage he considered that a sufficient period of time had passed to determine whether the problem of leg length discrepancy was going to settle, and at that time he considered that delaying remedial surgery would increase the risk of a more difficult operation and a higher risk of an unsatisfactory outcome: T108.7 - T108.14; (h)he felt that if he did not revise the hip at the 6 weeks stage the plaintiff would get worse and develop chronic pain, and even if the discrepancy was corrected after a period of 12 months, he felt the ultimate level of pain and disability was not going to improve: T110.30. 184Dr O'Carrigan considered and weighed the above matters and recognised that an important decision had to be made on whether or not to re-operate, so he took some time to make careful measurements and to consider the appropriate clinical course: T104.10 - T104.15. 185Dr O'Carrigan based his final advice to intervene and re-operate on his assessment that the plaintiff was not coping with her pain and her leg length discrepancy, and because her level of pain was increasing and not decreasing. In those circumstances, he strongly felt that operative intervention at that stage was the best course, and he advised the plaintiff accordingly: T108.29 - T108.36. 186After considering those matters he telephoned the plaintiff to discuss his views over the course of several calls and he then arranged for her to see him in consultation with her family for a discussion and a decision. That consultation took place on 23 September 2011: T108.15 - T110.37. 187The deciding factors that led to the conclusion that Dr O'Carrigan should recommend re-operation were that the pain was getting worse and not better, her function was getting worse and not better and there was a significant clinical leg length discrepancy: T110.35. 188The relevant cross-examination challenges made to Dr O'Carrigan's evidence of the matters outlined in the preceding paragraphs, including his responses, are summarised as follows: (a)He was concerned about possible leg lengthening at the time the plaintiff reported it to him whilst she was still in hospital, but at that stage he hoped it would settle down by the 6-week mark, and if not, at that time, when it had not, and that is why he suggested intervention by revision surgery at that time: T157.5; (b)He said it would have been difficult to make a definitive examination whilst the plaintiff was in the post-operative phase: T158.5; (c)Whilst in hindsight, it would have been possible for him to have obtained standing x-rays for measurement purposes at an earlier stage than at 6 weeks, he went on to say that this would not have changed his management of the plaintiff as he would have had to let the wound heal and determine the clinical progress before reviewing the plaintiff again 6 weeks after the first operation: T158.20 - T158.25; (d)It was suggested that the plaintiff preferred a posterior approach to the revision surgery, to which he responded that he was not of that understanding: T128.40 - T129.10; T129.15. In any event, the consent form for the second procedure had no such qualification (Exhibit "B", p 86) and the options were discussed with the plaintiff: paragraph [140] above; (e)He agreed with the proposition that a 1cm leg lengthening can be tolerated by some patients without difficulty (T134.15) but at the other end of the spectrum there are some patients that do not cope well with such a discrepancy, and have increasing pain and disability, requiring revision, emphasising that not all patients are the same: T137.15 - T137.25. 189Dr O'Carrigan was asked whether, as at 8 August 2011, when the plaintiff made him aware of her perception of a leg length discrepancy, that reasonable skill and care on his part required that he should have arranged a further x-ray evaluation at that time: T158.30. In his response at T159.40 - T159.48, he replied as follows: "... A. Kelly had had X ray examination. She had had a post operative X ray. I knew from that post operative X ray that her components were well aligned. Her hip was located. I knew that there was no peri prosthetic fracture. I have explained that erect leg X rays at that point in time I don't think would have been interpretable. The only other X ray that could have been taken was an AP pelvis showing both hips. And so one can argue that I should have done an AP pelvis. I may have been able to demonstrate with careful assessment that there was a discrepancy there, but having done that I still believe my approach would not have changed." 190Dr O'Carrigan's evidence on the above matters was not relevantly contradicted on matters of principle. The attack on his reasons for the suggested timing of the revision surgery was in effect an attack on his clinical judgment. The evaluation of that attack must be made in the light of the expert evidence on the issue.

Plaintiff's circumstances after second operation 191On 13 October 2011, Dr O'Carrigan wrote to the plaintiff's general practitioner in the following terms: "Kelly had her revision surgery on the 23 rd September. We were unable to get the hip out through the anterior approach because it was already ingrown at seven weeks so we reduced the hip, closed that wound and did a posterior approach. Then we were able to successfully remove the femoral component. We inserted a smaller size component 1cm further distally. She has actually done well since then. Her leg lengths are now equal. She is still requiring some Oxycontin but her pain is settling down quite nicely and her wounds have healed beautifully. I am confident we have corrected the problem which is of considerable relief to Kelly. I am going to see her again in seven weeks with some erect leg x-rays looking at the leg lengths. She can progress from two crutches onto one crutch, then a stick as tolerated. She recently had a Doppler ultrasound which is negative for DVT so she can go on to Clexane for one further week and then low dose Aspirin. I will review her in seven weeks and will keep you informed." 192On 27 November 2011 Dr O'Carrigan ordered an x-ray of the plaintiff's left hip. On 30 November 2011 that x-ray was reported as showing no abnormalities. 193The plaintiff was scheduled to see Dr O'Carrigan on 30 November 2011. On that day Dr O'Carrigan wrote to the plaintiff's general practitioner in the following terms: "Kelly has definitely improved since I last saw her. She is improving with pain relief as well as her activity levels. She still feels she has a bit of a limp. The inside adductor area feels weak. She is unable to sit for long periods and she feels stiff around the hip. She is taking about 1 Panadeine Forte per day as well as some relaxants occasionally. She doesn't use a stick at home but she uses it outside. Kelly is attending physiotherapy and doing a lot of her own physio and I have a report from the physiotherapist at Mt Druitt Hospital indicating that she is making significant progress in terms of active range of motion, straight leg raises, abduction and mobility status as well as pain free wall squats. On 14 October 2011 she was unable to do that and on 29 November 2011 she is doing 45 degrees so she is making good progress. Erect leg x-rays shows that her leg lengths are equal and that fits with her clinical examination so we got her leg lengths right which is very pleasing and that has detensioned very (sic) thing. She is improving. It is going to be a 12 month process for her to fully resolve. I will see Kelly again in another 3 months with an x-ray and I will keep you informed." 194The plaintiff did not attend that further consultation for review scheduled for February 2012. In the meantime the plaintiff had investigated legal redress, and her solicitor filed a statement of claim on her behalf on 13 June 2012.

Medical and allied reviews of the plaintiff 195On 4 occasions between 26 November 2011 and 31 March 2012, the plaintiff consulted a clinical psychologist, Ms Kathleen Pullan. Those consultations revealed range scores in the severe range for depression traits, scores in the extreme range for anxiety and severe range scores for stress. This was attributed as being related to the second surgery. The plaintiff related her distress as being influenced by the posterior post-operative scar. 196Ms Pullan recorded a past history of the plaintiff having been assaulted and robbed, which resulted in the plaintiff being reactive to small noises and perceptual disturbances. It was against the background of that history that Ms Pullan identified the plaintiff's symptoms related to the second surgery as being unwanted ruminative thinking about the surgery, emotional lability, constantly worrying about it, exaggerated startle responses, sleeplessness, body image issues, financial stress, physiological pain and limited mobility. These problems were treated with cognitive behavioural therapy, mindfulness therapy and breathing control. 197Ms Pullan considered the plaintiff has been left with significant symptoms consistent with depression, anxiety and adjustment issues. 198On 23 March 2012 the plaintiff underwent physiotherapy assessment by Mr Elias. As a result, restricted duties were suggested to her, namely to avoid working for more than two full work days without a rest day in between. 199On 12 April 2012, at the request of her solicitor, the plaintiff was examined by Dr Bracken as part of his liability review. He noted a 2cm relative atrophy of the left thigh, an 11cm anterior scar and a related scar from the second surgery, as well as a 20cm oblique scar over the left buttock. Dr Bracken noted some restriction of movement in the plaintiff's left hip and some groin tightness. Dr Bracken noted that as it was only 5 months (sic for 7) since the revision surgery when he examined her. He considered that there was still some scope for further bedding in of the prosthesis. Even though he thought there was some scope for improvement in hip function over time, he considered the plaintiff would not achieve a greater degree of external rotation than that which she had at that examination. 200On 24 April 2012, at the request of her solicitor, the plaintiff was examined by Dr Klaas Akkerman, a consultant psychiatrist. He recorded a history of insomnia, tearfulness, irritability, reduced concentration and memory, reduced interest, energy, appetite and libido. He diagnosed the plaintiff as having major depression. He considered the plaintiff had recovered from the earlier psychological condition due to the bashing and robbery, and he characterised that earlier depression as having been mild. Dr Akkerman had been required for cross-examination by the defence, however that requirement was not maintained on the agreed proviso that no adverse comment would be made by the plaintiff to the effect that the report of Dr Akkerman and his expressed opinions were not challenged. 201On 12 May 2012, at the request of her solicitor, the plaintiff was examined by Dr Cholm. Williams, a consultant plastic and reconstructive surgeon. He described the plaintiff's scarring, being a wide scar on the anterior thigh associated with a minor contour depression, a finer scar posteriorly, and a very small scar just above that latter scar. He identified the presence of those 2 scars and the related contour deformity as being due to the second procedure, and noted these would be permanent. Those scars were the subject of photographs: Exhibit "C". 202On 8 June 2012, the plaintiff underwent a further physiotherapy assessment by Mr Elias. He identified the need for the plaintiff to continue with modified exercise to achieve optimum outcome. 203On 6 July 2012, the plaintiff's general practitioner certified that for a period of 3 weeks, the plaintiff should avoid lifting, twisting or bending movements. 204On 20 August 2012, at the request of her solicitor, the plaintiff was examined by Dr Roger Brightman, a consultant orthopaedic surgeon. In his report of that date, Dr Brightman noted the plaintiff's main concerns to have been a restricted range of motion in the left hip, particularly with forward flexion and abduction in flexion, continuing pain in the left groin and buttock, and abnormal sensation down the lateral aspect of the left leg. No leg length discrepancy was noted to be present at that time. 205Dr Brightman considered the restriction in the range of movement of the plaintiff's left hip was due to scar tissue from the two previous procedures carried out in relatively short succession. He noted that scar tissue was less supple than normal muscle and ligamentous tissue, and he thought there was adhesion of tissue planes. He considered that there was scope for improvement by using the medication Lyrica. 206Dr Brightman considered that the loss of range of left hip motion was causing limitation in all of the plaintiff's activities of daily living and in her work activities. It appears from Dr Brightman's report that he was unable to differentially identify the degree of disability due to each of the particular procedures that had been carried out on the plaintiff's left hip region. 207On 27 November 2012, at the request of the defendant's solicitor, the plaintiff was examined by Dr Rosalie Wilcox, a general and forensic psychiatrist. The resultant report of Dr Wilcox was dated 15 January 2012 (sic for 2013). Dr Wilcox obtained a history of the plaintiff having fluctuating moods, episodes of tearfulness, disrupted sleep, feeling on edge, panic, impaired concentration, forgetfulness, weight gain, impaired self-image and increased use of alcohol as a relaxant. Using the DSM IV-TR nomenclature, Dr Wilcox diagnosed the plaintiff as having an adjustment disorder with anxious and depressed mood, with a pre-existing anxious disposition that pre-disposed her to react adversely to stress. She also noted the presence of stress that was affecting the plaintiff's relationship. 208Dr Wilcox attributed part of the plaintiff's anxiety to the revision surgery. She did not agree with Dr Akkerman's diagnosis of major depression, nor did she agree with Dr Akkerman's treatment recommendations. 209On 24 January 2013, the plaintiff underwent a number of MRI studies at the request of her general practitioner. The MRI of the pelvis and left hip showed moderate atrophy of the left gluteus minimus and medius muscles. No other abnormalities were reported other than the presence of the prosthesis. The MRI of the left thigh showed a thickened and scarred distal aspect of the semimembraneous tendon and mild atrophy of the related muscles. There were MRI scans of the left knee and the lumbar spine that happened to have no bearing on the case: Exhibit "B", pages 53-54.

Plaintiff's residual problems 210From a physical perspective, as a result of the second operation, the plaintiff has some restriction of movement in her left hip. She has pain in her left groin and in her lower back. She is restricted in her ability to lift due to pain in her left leg. She finds it necessary to rest her leg at the end of the day. She is no longer able to power walk. She finds sitting for prolonged periods more uncomfortable than standing. She cannot cross her legs. She must lift her left leg with her hands when getting into a vehicle. Her leg tends to turn inwards when she negotiates stairs. She experiences a paddling sensation when her left foot makes contact with the ground. She is less able or inclined to go boating and snorkelling due to access and egress issues with leisure boating. 211The plaintiff continues to experience altered sensation in her left thigh. She has reduced capacity for house cleaning and her previous domestic tasks, including lawn and garden work. She limps after she over-exerts her left leg. She has gained weight. She continues to have physiotherapy treatment. She experiences pain when carrying out some of the activities of daily living. She is not able to easily effect a turn when in certain positions. She has additional scarring to her anterior thigh and scarring to her buttock and posterior thigh. She is unable to squat or sit for prolonged periods. As a result, she is restricted in some of the more physical aspects of her work. 212The plaintiff has also been emotionally affected by the circumstances of having to deal with leg lengthening and the surgical treatment required to remedy that problem. Initially, she was distraught when she realised the effect leg lengthening had on her mobility. This has become magnified by her previous experiences of post-traumatic stress. She remains anxious and depressed. She is affected by the symptoms noted in the report of Dr Akkerman. She is self-conscious about the additional scarring from the second procedure, although she does not intend to have corrective surgery on those scars, presumably due to concern over having further surgery. 213The above disabilities require further consideration and analysis on the issue of damages.

Mitigation 214The plaintiff has sought out prompt and appropriate treatment. She also returned to work when she was able to do so. There is no reasonable basis for arguing that she had failed to mitigate her damages, and no arguments to that effect were advanced by the defence. In my view, from a mitigation perspective, nothing turns on the fact that the plaintiff does not intend to have further surgery on her scars.

Survey of expert reports on liability issues 215In the paragraphs that follow, before analysing the concurrent expert evidence, I set out the details of the expert opinions on the liability issues in chronological sequence in order to record the manner and the sequence in which that evidence evolved in this case. 216The first liability opinion was obtained from Dr Bracken, who examined the plaintiff on 12 April 2012. Dr Bracken's report was issued on that same date. Other than providing some relevant background, the products of Dr Bracken's examination of the plaintiff were of limited contribution to his expert analysis on technical matters, as the critical events had occurred during surgery. 217In essence, Dr Bracken's opinion that was critical of Dr O'Carrigan's treatment was based upon inferences drawn from the documentary materials presented to him by the solicitor for the plaintiff, and from the fact the plaintiff had obtained the adverse result of left leg lengthening following the first procedure. Those matters require close examination in connection with deciding the central issues. 218The report of Dr Bracken dated 12 April 2012, at page 6, stated: "Ms Lange underwent left total hip replacement on 2 August 2011 when a ceramic to ceramic type uncemented prosthesis was inserted. Following that operation x-rays of her pelvis and both legs were taken on 15 September 2011 and the report states that the right hip outlines normally. A left sided THR is noted. There is satisfactory alignment of the implanted non cemented prosthesis. There is a moderate pelvic tilt. No significant degeneration is noted in the knee joints on either side. A leg length difference of 2.8 cms in favour of the left leg is seen. In follow up in the post operative period Dr O'Carrigan noticed that her hip was tight and tended to be abducted and that there was certainly a degree of absolute leg length inequality. I think that her presentation in the post operative period was such that he realised that he hadn't allowed for the short neck of femur on the left side that was part of the deformity and hadn't inserted his femoral component far enough causing a degree of leg lengthening and tightness in the articulation. In my experience ceramic hips are intolerant of undue compression pressures and under those circumstances tend to seize up. I think this happened in her case and Dr O'Carrigan realised it and as a result told her that she had no alternative but a revision operation and the sooner the better." 219The report of Dr Bracken dated 12 April 2012, at page 7, then went on to state: "You ask me various questions in respect of Dr O'Carrigan's liability in the matter. In my opinion it is evident that in performing the initial total hip replacement his intentions were good but he made an error in not allowing for the short neck when he was inserting particularly the femoral prosthesis. This resulted in a tight fit and a lengthening of the leg which he recognised as being an intolerable situation and was forced to recommend a revision operation as soon as possible and that was carried out. Ms Lange now has a satisfactory total hip replacement which is still bedding in and it would appear that given time the result would be a satisfactory one from the second operation. Needless to say the first operation involved misjudgement. I would not say that the operation was incompetently done but only that a mistake in judgement occurred which effectively scuttled the operation and resulted in the necessity for a revision." 220On 20 November 2012, at the request of the solicitor for the plaintiff, Dr Conrad prepared a liability report which was based upon a review of the papers forwarded to him by the plaintiff's solicitor. Those papers included the cited opinion of Dr Bracken dated 12 April 2012. Dr Conrad's opinion was in the following terms: "In the operation by Dr O'Carrigan on the 2nd August 2011,I totally agree with Dr Bracken's opinion that Dr O'Carrigan in his first operation had not allowed for the short neck of the femur on the left side and did not insert the femoral component far enough down the shaft of the femur and this caused a degree of leg lengthening and tightness in the articulation. ... The lengthening, in my view and from the measurements given, was a minimum of 2cms or greater and as Dr Bracken points out, ceramic hips are intolerant of undue compression pressures and tend to seize up. This and the fact that Ms Lange was distressed by her leg inequality necessitated the revision procedure. As per Dr Brighton's report, the second procedure has not resulted in a good result and Ms Lange has been left with pain, restriction of movement and difficulty in standing and walking. This has reduced her work capability. In answer to your questions as to liability, it is my opinion that Dr Tim O'Carrigan in his treatment and care of Ms Kelly Lange did not act in a manner that at the time the Services and Care were provided was widely accepted in Australia by Rational Peer Professional Opinion as Competent Professional Practice in Australia. The reason for this falling short of Competent Professional Practice was the fact that Dr O'Carrigan had not allowed for the short neck of femur due to the underlying congenital abnormality resulting from the Perth's Disease or slipped femoral epiphysis and had not inserted the femoral component far enough down the femur causing a degree of left leg lengthening and tightness in the articulation. The consequences of this falling short of Competent Professional Practice by Dr O'Carrigan to Ms Lange was that she needed a second operation to revise the femoral prosthesis and this necessitated a second very large and unsightly scar laterally and posteriorly, as described by Plastic Surgeon, Dr Cholm Williams. Also, Ms Lange has been left with much more pain and stiffness than she would likely have had, had only the one operation been correctly performed. Finally, should the revision of the prosthesis been done earlier, then it is a possibility that the revision operation may have been able to have been done through the original anterior incision and this may have precluded the necessity of a second incision causing additional scarring." 221Following service by the plaintiff's solicitor of the above reports of Dr Bracken and Dr Conrad, Dr O'Carrigan's solicitor commissioned an expert report from Dr Sullivan. In his report dated 8 January 2013, Dr Sullivan stated: "...In attempting to achieve restoration of anatomy including leg length and offset the general approach is to start with templating which identifies the intended approximate size of implant and more importantly the level of the femoral neck osteotomy. This is generally referenced off the lesser trochanter and measured in millimetres. This is a good reference point as the base of the neck of the implant sitting at the level of the osteotomy is a fairly reproducible and identifiable technique. Other intraoperative indicators of restoration of the anatomy include soft tissue tension such as the anterior capsule, tension in the iliopsoas or in the rectus femoris, ease of reduction and when the patient is in the lateral decubitus position aligning the knees and heels to see that they are symmetrical. Other intraoperative indicators are the centre of the femoral head in reference to the greater trochanter and some surgeons use intraoperative markers such as temporary screws which are inserted before making the osteotomy of the femoral head so that measurements can be made later after reduction with the implants in situ. If the patient is in the supine position an intraoperative x-ray can be taken but most operating tables do not accommodate a full x-ray of the pelvis which is the only really accurate way of assessing the postoperative anatomy. The use of an image intensifier can be helpful to check cup orientation, femoral sizing and would give some indication of length but as both hips cannot be seen at the same time it is not completely accurate. Generally it is accepted that all of these techniques have their drawbacks and are not infallible and it has not yet been possible to completely eliminate leg length discrepancy following total hip replacement. The incidence of leg length in the general community is quite high and it is considered that most people can accommodate up to 1 cm of leg length inequality without having disability. A sudden increase in leg length such as occurs with a hip replacement is more difficult to accommodate particularly early on although with time most patients with up to 1 cm or so of lengthening adjust and do not require any further intervention or even a shoe raise. This may not be the case in patients of shorter than average stature. Following total hip replacement particularly if there is some increase in offset many patients feel that the leg is long in the early stage. This sensation nearly always settles with a period of stretches and physiotherapy. Even patients who have been lengthened up to 1 cm often adjust in time and this would be one reason why it would be reasonable not to rush into revision surgery. As such, I think it is reasonable for Dr O'Carrigan to have allowed a small period of time to elapse before performing the revision procedure. Early reoperation may also have an increased risk of deep vein thrombosis and any revision surgery carries an increased risk of infection. ..." 222The report of Dr Sullivan then went on to state: "Currently it is still not possible to completely eliminate leg length discrepancy following total hip replacement. As previously stated, most patients will accommodate up to 1 cm of lengthening without disability. For this to occur it may take over twelve months for the soft tissues to adjust. When the lengthening is longer than that a decision needs to be made as to whether the patient is willing to accept a shoe raise or to proceed to revision surgery. Generally with time, the symptoms of pain and tightness from the lengthening would resolve and the ongoing problems are usually only really related to the leg length discrepancy itself. Dr O'Carrigan felt in the end that the true leg length discrepancy was in the order of 1.8 cms. In the revision procedure he recessed the new implant a further centimetre and he reduced the neck to a short neck which would have shortened the overall leg length by another couple of millimetres and the offset by perhaps a couple of millimetres. In my opinion, Dr O'Carrigan did not depart from standards that in 2001 were widely accepted in Australia by peer professional opinion as competent professional practice. I would also note that at the original procedure a second orthopaedic surgeon was assisting and acting presumably as a mentor. That particular orthopaedic surgeon is a well regarded hip replacement specialist and clearly he also did not consider that Dr O'Carrigan departed from competent professional practice during the procedure. From viewing the x-rays I believe the true intraoperative lengthening was just over 1 cm and I believe that this is within the bounds of what can occur in total hip replacement even performed reasonably competently. I have read Dr Bracken's report and I am unaware that ceramic hips are less tolerant of lengthening than other bearings. I would agree that a time period of up to two years should be allowed before an assessment is made as to whether there is any permanent impairment." 223The reference in the third-last paragraph of the above quotation to the presence at the operation of another well regarded orthopaedic surgeon and the assumed views of that surgeon can carry no weight without evidence of that surgeon's actual views. In that regard, I place no weight on that aspect of Dr Sullivan's opinion. 224The plaintiff's solicitor subsequently asked Dr Bracken to consider the opinion of Dr Sullivan. As a consequence, Dr Bracken issued a supplementary report dated 3 April 2013, in which he partially changed his earlier views on the timing of the second procedure, where he stated: "I have read the report by Dr Sullivan dated 8 January 2013 and, in general terms, I agree with everything he has to say. Insofar as I made the remark that ceramic hips were more inclined to lengthening and tightness stems from my own personal experience of type tight hips with ceramic implants but those experiences were early in the introduction of ceramic based hips. That having been said, the tightness and lengthening of the ceramic hip in the case of Kelly Lange was very similar to those that I revised years ago. In respect of Dr Sullivan's report it is my opinion that the tightness and apparent length discrepancy in the case of Kelly Lange was such that I am doubtful that it might have settled down had the operating surgeon persisted with it for 12 months. I do believe revision was necessary. The other comments I have made in the Opinion of my report remain totally valid." 225The plaintiff's solicitor also asked Dr Conrad to consider the opinion of Dr Sullivan. As a consequence, Dr Conrad issued a supplementary report dated 13 August 2013, in which he stated: "In his report and from your Letter of Instructions, Dr Sullivan believes the intra operative lengthening was just over 1 cm and this is within the bounds of reasonableness. If it is accepted that the length difference is one centimetre then it is questionable whether any early revision operation needs to be done. ... Dr O'Carrigan's revision operation was undertaken on 23 September 2011. In other words, the revision operation done by Dr O'Carrigan was done six weeks after the original operation. On Dr Sullivan's own report, there is no doubt that Dr O'Carrigan did not allow a sufficient period of time for Ms Lange to adjust to the lengthened leg before rushing into revision surgery. ... Accepting that Ms Kelly Lange's lengthening was about 1 cm, it can be clearly said that according to Dr Sullivan's report, Dr O'Carrigan should have waited at least 12 months before recommending revision surgery. In the last page of his report, he appears to recommend that up to two years should be allowed before an assessment is made as to whether there is any permanent impairments(sic). Accepting Dr Sullivan's report and opinion, it can be said that should Ms Lange have been counselled to try conservative treatment for a year with the possibility of a shoe raise and that after a year had she adjusted to such a treatment, then on the balance of probability, she would not have had the revisionary surgery and the current disabilities that she is currently suffering. It is my view that the revisionary surgery has left her with scarring and a worse result than had she not had the surgery and had been allowed to adjust to the effects of the lengthened leg." 226On 30 August 2013, at the request of the solicitor for the plaintiff, Dr Bracken issued a further short supplementary report in which he stated: "I have reviewed my main report and supplementary report today. I agree with Dr Sullivan that the overall lengthening of the left leg following the initial operation was just over 1 centimetre and measured radiologically at 1.1 centimetre. I accept that a lengthening of 1.1 centimetre is within the bounds of reasonableness for such an operation. It is true that Kelly Lange could have been treated conservatively following the first operation with a raise to the right shoe and physiotherapy and that if she was treated in that manner that it was liable to go on for 12 months. It is my opinion that had she been treated conservatively for 12 months after the first operation that there is a high probability that she may well not have needed the second operation with its associated disabilities." 227The force of Dr Bracken's last quoted comment has to be gauged alongside the matters that Dr O'Carrigan had to consider when he made his judgment in advising the plaintiff as to the timing of a revision procedure.

Concurrent evidence by liability experts 228When the evidence of Dr Bracken, Dr Conrad and Dr Sullivan was taken concurrently, the reasons underpinning their earlier expressed opinions were explored on the issues of first, the appropriateness of the leg lengthening result from the first procedure and secondly, as to the appropriateness of the timing of the second procedure for revision of leg lengthening. 229The individual elements that comprised those reasons both, for and against the propositions in question, are set out in the paragraphs in paraphrased form that follow in order to evaluate the content of that evidence in accordance with the requirements of UCPR r 31.27; Sch 7, cl 5(c), the defence under s 5O of the CL Act, and the requirements for expert evidence generally: Makita (Australia) Pty Ltd v Sprowles [2001] NSWCA 305; (2001) 52 NSWLR 705; Dasreef Pty Ltd v Hawchar [2011] HCA 21.

Expert evidence on standard of care in first procedure 230With regard to leg lengthening as a result of the first procedure, on the question of whether there was any evidence to support the proposition that Dr O'Carrigan's actions had breached or departed from the expected standard of care: Experts' views in favour of finding breach of duty of care in first procedure (a)The reasons in favour of concluding there had been a departure were identified as being: (i)The requirement of a reasonably skilled and competent surgeon performing hip replacement surgery is to make the right choice of prosthesis: Dr Sullivan: T189.30-T189.34; (ii)If the correct intra-operative sequences are followed and the wrong femoral stem is selected from the range of sizes available, this is suggestive of the occurrence of error in the application of the sequencing procedures: Dr Sullivan: T200.5; (iii)In hip replacement surgery most operators achieve the correct result most of the time: Dr Sullivan: T200.17; (iv)In retrospect, regardless of the position of the femoral neck cut, Dr O'Carrigan should have gone with the smaller sized implant from the outset, as occurred at the second procedure: Dr Sullivan: T200.49-T201.2; (v)The argued error of judgment in the first procedure that resulted in the insertion of the wrong sized femoral stem implant was that such a result was not acceptable: Dr Bracken, T186.15 - T186.20, agreed to by Dr Conrad: T186.24; (vi)In the first procedure the size 2 femoral stem could have been passed down the femur another centimetre or so, but only if the bone would be assessed as being able to accommodate this: Dr Sullivan: T189.4; (vii)Dr O'Carrigan should be taken to have been aware at the time of testing for appropriate fit and before closure, that there was a problem of tightness when the hip components were reapposed, in that if the implant fit was tight, flexion would have been inhibited, and the leg would have been seen to have been abducted, which would have given apparent lengthening to the left leg, the inference being that this ought to have been recognised and corrected at the time: Dr Bracken: T205.32 - T205.50; Experts' views against finding breach of duty of care in first procedure (b)The reasons against concluding there had been a departure were identified as being: (i)Unfortunately, leg length discrepancy sometimes occurs even when all the required intra-operative procedural steps normally undertaken are in fact carried out: Dr Sullivan: T186.35 - T186.40; Dr Bracken: T189.49. This can occur even in the most expert hands, the inference being such an occurrence is not necessarily a breach of duty of care: All experts: T189.50 - T190.10; (ii)According to the judgments Dr O'Carrigan made during the surgery, where he thought the femoral prosthesis "felt" correct, he should not be criticised for using a size 2 femoral stem: Dr Sullivan: T187.2; (iii)The need for the surgeon to stop broaching the femur at broach size 1 was a conclusion arrived at through a judgment made in hindsight: Dr Sullivan: T188.50; (iv)If Dr O'Carrigan had in fact taken all the intra-operative precautionary steps [referred to in the evidence] then he should be taken to have acted appropriately in accordance with peer professional practice: Dr Bracken: T196.45; (v)Dr O'Carrigan should not be criticised simply because the result was not as he wanted: Dr Sullivan: T197.4; (vi)The broach size used by Dr O'Carrigan was appropriate to the cut to the femoral neck: Dr Sullivan: T198.20; (vii)There is a tolerance for error in selecting one sized femoral stem over another, but that tolerance is small: Dr Sullivan: T197.19 - T197.40; (viii)Determining the correct amount of broaching by toggling the broach within in the femoral canal is a matter of "feel" by the operating surgeon: Dr Sullivan: T198.35 - T198.40; (ix)The described facts do not permit the inference that the broach was too tight on the bone thereby resulting in leg lengthening when the femoral stem was fitted: Dr Sullivan: T199.11 - T199.14; T199.32; (x)The radiology scan with the pre-operative marking made by Dr O'Carrigan to represent the proposed cut to the femoral head "looks about right", subject to the caveat that the templates (which were not tendered by either party) would have assisted in confirming proper size; the further qualification is that when using the anterior approach to hip replacement surgery, there are not a lot of reference points or anatomical landmarks available to be used for making the initial cut to the femoral head: Dr Sullivan: T201.15 - T201.35; Dr Bracken; Dr Sullivan: T201.40 - T202.1; (xi)The marked line to guide the femoral head cut in relation to available anatomical landmarks was an appropriate measure to minimise risk (of error), and represented good practice in the jurisdiction at the time: T201.20 - T202.1; (xii)Dr Bracken's criticism of Dr O'Carrigan's method of testing the tension of the soft tissues must be read as being subject to the caveat that when he performed anterior hip replacements he never used a traction table with a fixed boot, and it should be noted that in those circumstances, after the required release of the capsule, the muscle and soft tissues are much more elastic, the inference being that the criticism by Dr Bracken that Dr O'Carrigan must have felt tissue tightness when he test-fitted the component, may be unfounded: Dr Sullivan: T206.34 - T206.45.

Expert evidence on timing of revisionary surgery 231With regard to the timing of the second procedure which revised the first procedure to correct leg lengthening, on the question of whether there was evidence that, in recommending that procedure, Dr O'Carrigan had departed from the expected standard of care by re-operating too soon: Experts' views suggesting intervention was too soon (a)The reasons in favour of the conclusion that Dr O'Carrigan had re-operated too soon were identified as being: (i)Patients are encouraged not to have a revision if they think they can accommodate the discrepancy because revisionary surgery has its risks: Dr Sullivan T210.40; (ii)The intervention for revision at 6 weeks was a hasty one: Dr Bracken: T213.1; (iii)Revision should have been delayed for perhaps a year, because 6 weeks was too short a period of time: Dr Conrad: T186.30; (iv)Revision surgery at 6 weeks was hasty in a non-disaster situation where a 1.1cm shortening (sic for lengthening) should have been tolerated by the patient over time: T187.20 - T187.28, agreed by Dr Conrad: T187.35; (v)Dr Bracken's amended opinion as to timing for revision was that the time between the original surgery and the revision procedure was extremely short: Dr Bracken: T208.8; (vi)Dr Bracken considered that as there was about only 1cm limb length difference there was a fair chance of the soft tissues accommodating to the problem with conservative treatment, and that at the end of 12 months, an osteotomy could have then been used to get the prosthesis out if that was still required at that time: Dr Bracken: T208.14 - T208.25; (vii)Whilst it is true that Dr O'Carrigan had to assess whether, in the future, the plaintiff was going to accommodate a true leg length discrepancy of 1.1cm, the assumption was that she would accommodate that discrepancy: Dr Bracken: T212.1 - T212.5; T212.43; (viii)Since the extent of true leg lengthening would not change, but the patient's perception of leg length would change over time, when deciding upon revisionary surgery it is most important to make an assessment as to how the patient is coping: All experts: T209.25 - T209.41; (ix)When deciding whether or not to intervene and to revise the procedure, the critical judgment to be made by the surgeon is whether, based upon the evidence before him, it was likely that the patient would posturally compensate over time: Dr Bracken: T209.42 - T209.47; (x)In that regard, Dr Conrad considered that 6 weeks was too soon to intervene and re-operate because the patient would still have had a lot of post-operative pain at that time, and therefore at 6 weeks the ability to compensate may not have been as well as perhaps at 6 months or a year after the original procedure: Dr Conrad: T210.1 - T210.5; (xi)The phenomenon of patients having a leg length discrepancy of plus or minus 1.1cm after surgery is not all that uncommon and most people will accommodate a discrepancy of that order very easily without problems, provided that they had reasonable movement in the hip: Dr Bracken: T210.47 - T211.7; (xii)A lot of people waking up after this type of surgery with a centimetre of leg discrepancy do adjust, but that does not certainly apply to everybody: Dr Bracken: T211.16; (xiii)Intervention for revisionary surgery to correct leg length discrepancy is a judgment call for the surgeon to make, based upon the surgeon's view of how the patient appears to be coping, and the surgeon's assessment of the likelihood of the patient continuing to be able to cope: Dr Sullivan: T211.18 - T211.23; (xiv)The plaintiff's complaint of increasing groin pain after her trip to Forster indicated that it was reasonable for Dr O'Carrigan to form the view that she was not going to cope with those pains so that re-operation was justified: Dr Sullivan: T211.25 - T211.32; [s 5O]; (xv)The risks of a more extensive procedure being required at a later stage if corrective intervention was delayed was probably on the small side: Dr Bracken: T213.8; (Contrary to Dr Sullivan at T213.15, who thought that the timing of the intervention was reasonable) (xvi)A good surgical dictum was when in doubt, wait and see whether the patient was able to cope: Dr Conrad: T213.20 - T213.26; Experts' views in favour of the early intervention (b)The reasons supporting the timing of Dr O'Carrigan's re-operation were identified as being: (i)Revisionary surgery performed at 6 weeks after the original procedure meant it was easier to remove the femoral stem at that stage rather than waiting a year (because the bony ongrowth on the prosthetic component would have been to a lesser extent), and then having to perform a more difficult procedure to split the femur to remove it, and incur higher risks of complication in such a later procedure: Dr Sullivan: T187.15; (ii)At the time Dr O'Carrigan was told by the plaintiff that she had perceived her left leg had been lengthened (or was lopsided), at Day 6 post-operatively, Dr Sullivan would have done nothing else at that stage except ordering physiotherapy and rehabilitation: Dr Sullivan: T204.33; (iii)The decision on whether or not to intervene and to revise the operation after 6 weeks was a judgment call by Dr O'Carrigan that had to be based upon rational information: Dr Sullivan: T213.43 - T213.48; (iv)Dr O'Carrigan is an expert to whom most surgeons would send patients requiring leg length discrepancies to be corrected: Dr Sullivan: T214.24 - T214.28; (v)When an operating surgeon is assessing whether or not to intervene, there are no absolute considerations, and if the surgeon was confident that the patient would accommodate the discrepancy over time, then revisionary surgery for correction of leg length discrepancy should not proceed, the essential question being whether the patient was prepared to put up with the problem whilst waiting to see if accommodation of leg length discrepancy occurred over time, noting that every time the patient walked bare footed she would know her leg was longer: Dr Sullivan: T214.30 - T214.46; (vi)In circumstances where the operating surgeon is unclear as to whether the true leg length discrepancy was 1.1cm or 1.8cm, as opposed to functional discrepancy, the rational thing for a surgeon to do in such circumstances would be to review the patient on a frequent basis to try and determine the true leg discrepancy and to then operate when and if the patient's inability to cope has been ascertained: Dr Conrad: T215.34 - T215.41; (vii)The rational deciding factors for determining whether or not to take a wait and see course as opposed to intervening earlier with corrective surgery would be a combination of factors. These were: how long the discrepancy was thought to be on measurement by scanogram, an assessment of the patient's soft tissue balance, an assessment of the patient's mental state, an assessment of whether it was thought the patient was likely to adjust to the leg lengthening or discrepancy problem, an assessment of whether the patient would tolerate a temporary shoe raise. These considerations were all part of the matters required to be considered in such a judgment call: Dr Sullivan: T215.43 - T216.5; (viii)If the advice to the patient was to the effect that there was no alternative course available but to re-operate, advice of that nature or effect would have been incorrect as there was no absolute indication for re-operation: Dr Sullivan: T216.6 - T216.27. Exhibit "B" page 86 in fact shows Dr O'Carrigan identified the alternative treatment to be "watch and wait" which might lead to worsening of ongoing problems; (ix)Measurement of true leg length discrepancy was a process that was prone to error in that variations in measurement for true leg length discrepancy depended upon which particular method was used and which landmarks were taken for making the measurements: Dr Sullivan: T217.21 - T217.25; (x)As a tertiary expert on leg length correction, Dr O'Carrigan was in an advantageous position for measuring leg length discrepancy: Dr Bracken: T217.28 - T217.35; (xi)The measurement of leg length discrepancy is a moderately accurate process but it is not an exact science, where clinically, an allowance of a 10 per cent margin for variation would be appropriate in cases assuming the person who was undertaking the measurements was a clinician who had the expertise to make leg length assessments: Dr Bracken: T217.43 - T217.15; (xii)Dr Bracken considered the essential issue to be the plaintiff's post-operative tight hip. He said that clinically, the plaintiff had restricted ranges of hip motion. In those circumstances a judgment was required as to whether the plaintiff could accommodate the discrepancy. Dr Bracken's impression was "the treating surgeon had a bit of a panic" when he examined the plaintiff and then determined to revise the operation on the premise that if he left it any longer it was going to be more difficult to remove the prosthesis without beforehand giving detailed consideration of the counter-proposition of allowing a conservative course of treatment. Dr Bracken concluded, in retrospect, that it appeared the decision and the resultant operation had been made on a short time scale, which indicated to him that the revision procedure should have been undertaken at a later date after a period of conservative management. Dr Bracken's views in that regard were based on a consideration of the time scale in question: Dr Bracken: T217.48-T218.27; (xiii)Dr Sullivan agreed that if Dr O'Carrigan had formed the view that the plaintiff was unlikely to cope with the post-operative leg length discrepancy, then it was reasonable for him to have offered her remedial surgery in preference to a conservative approach: Dr Sullivan: T218.34 - T218.37. 232Before turning to the essential issues calling for decision against the background of the above portrayal of the array of expert evidence, the legislative framework for determining the liability issues needs to be identified.

Legislation 233The relevant provisions of the CL Act are s 5B, s 5C, s 5D and s 5O. 234Section 5B of the CL Act provides: 5B General principles (1) A person is not negligent in failing to take precautions against a risk of harm unless: (a) the risk was foreseeable (that is, it is a risk of which the person knew or ought to have known), and (b) the risk was not insignificant, and (c) in the circumstances, a reasonable person in the person's position would have taken those precautions. (2) In determining whether a reasonable person would have taken precautions against a risk of harm, the court is to consider the following (amongst other relevant things): (a) the probability that the harm would occur if care were not taken, (b) the likely seriousness of the harm, (c) the burden of taking precautions to avoid the risk of harm, (d) the social utility of the activity that creates the risk of harm. 235Section 5C of the CL Act provides: 5C Other principles In proceedings relating to liability for negligence: (a) the burden of taking precautions to avoid a risk of harm includes the burden of taking precautions to avoid similar risks of harm for which the person may be responsible, and (b) the fact that a risk of harm could have been avoided by doing something in a different way does not of itself give rise to or affect liability for the way in which the thing was done, and (c) the subsequent taking of action that would (had the action been taken earlier) have avoided a risk of harm does not of itself give rise to or affect liability in respect of the risk and does not of itself constitute an admission of liability in connection with the risk. 236Section 5D of the CL Act provides: "5D General principles (1) A determination that negligence caused particular harm comprises the following elements: (a) that the negligence was a necessary condition of the occurrence of the harm ( "factual causation" ), and (b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused ("scope of liability" ). (2) In determining in an exceptional case, in accordance with established principles, whether negligence that cannot be established as a necessary condition of the occurrence of harm should be accepted as establishing factual causation, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party. (3) If it is relevant to the determination of factual causation to determine what the person who suffered harm would have done if the negligent person had not been negligent: (a) the matter is to be determined subjectively in the light of all relevant circumstances, subject to paragraph (b), and (b) any statement made by the person after suffering the harm about what he or she would have done is inadmissible except to the extent (if any) that the statement is against his or her interest. (4) For the purpose of determining the scope of liability, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party. 237Section 5O of the CL Act provides: "5O Standard of care for professionals (1) A person practising a profession ("a professional" ) does not incur a liability in negligence arising from the provision of a professional service if it is established that the professional acted in a manner that (at the time the service was provided) was widely accepted in Australia by peer professional opinion as competent professional practice. (2) However, peer professional opinion cannot be relied on for the purposes of this section if the court considers that the opinion is irrational. (3) The fact that there are differing peer professional opinions widely accepted in Australia concerning a matter does not prevent any one or more (or all) of those opinions being relied on for the purposes of this section. (4) Peer professional opinion does not have to be universally accepted to be considered widely accepted." 238I now turn to a consideration of whether Dr O'Carrigan should be found to have been negligent as was argued on behalf of the plaintiff.

Legal principles for determining claim 239Allegations of negligence based on contended facts are matters that the plaintiff must prove by evidence, or reasoned inferences drawn from the available evidence, and in accordance with the requirements of s 5B of the CL Act. 240Having regard to the evidence of the technical intricacies inherent in the many procedural tasks involved in hip replacement surgery, as was explained by Dr O'Carrigan in his uncontradicted evidence (as summarised at paragraphs [93] to [100] above), it follows that this is not the type of case where a commonsense analysis of the observed or recounted sequence of events alone, uninstructed by expert evidence, can enable a court to conclude that negligence had occurred in either the primary procedure, or in the timing of the decision to re-operate: Adelaide Stevedoring Co Ltd v Forst [1940] HCA 45; (1940) 64 CLR 538, per Rich ACJ, at pages 563-564. 241In those circumstances, it is necessary to look to the expert evidence in order to seek guidance in discerning whether or not any acceptably reasoned arguments in favour of finding intra-operative negligence on the part of Dr O'Carrigan can be identified and sustained. 242It is plain from the evidence that the technicalities and procedural sequences involved in hip replacement surgery are based on principles derived from science, engineering and biomechanics. The application of those principles in surgical practice is an art for which the surgeon must draw upon his received knowledge, understanding and training when exercising professional judgment. 243The question of whether Dr O'Carrigan had, in the circumstances under review, departed from the standard of ordinary but reasonable skill and care expected of him in the practice of his art must be determined rationally, by reference to explanatory opinion evidence from his peers who are qualified to speak about such matters of judgment. 244If the analysis of the evidence from peers indicates that the claim made on behalf of the plaintiff is based on nothing more than conjecture, the conclusion that inevitably follows is that the allegations of negligence that are dependant upon an acceptance of peer criticism based on such conjecture, should not be accepted: Bradshaw v McEwans Pty Ltd (1951) 217 ALR 1 at p 5; Luxton v Vines [1952] HCA 19 at [8]; (1952) CLR 352 at pages 359-360. 245In determining whether Dr O'Carrigan had relevantly departed from the expected standard of reasonable care, the required analysis should be prospective, and not driven by hindsight considerations: Vairy v Wyong Shire Council [HCA] 62; (2005) 223 CLR 442 at [124], pages 461-463. 246Specifically, in Vairy, Hayne J identified the required approach at [126], p 461, as being: "That inquiry must attempt, after the event, to judge what the reasonable person would have done to avoid what is now known to have occurred. Although that judgment must be made after the event, it must seek to identify what the response would have been by a person looking forward at the prospect of the risk of injury." [Emphasis added] 247A surgeon is liable only for a default in not doing what he should have done when exercising reasonable skill and care. That standard does not involve omniscience for avoiding damage caused by a "mere error of judgment": Ainsworth v Levi [1995] NSWCA 9, p 5.40. 248In considering whether there has been a departure from the required standard of reasonable skill and care, there is some scope for allowing a degree of latitude for errors of judgment not amounting to breach of the standard of care: Dobler v Halvorsen [2007] NSWCA 335; (2007) 70 NSWLR 151, at [104]. 249The above principles will guide my determination of the issues calling for decision in this case.

Issue 1 - Alleged negligence concerning first procedure 250In analysing whether the adduced evidence supports a finding of intra-operative negligence having occurred in the first procedure, a number of preliminary matters need to be stated. 251The first such matter is to identify the duty of care owed to the plaintiff and the scope and content of that duty. 252In that regard, Dr O'Carrigan owed the plaintiff a duty of care that required him to take reasonable skill and care as would be expected from an orthopaedic surgeon exercising ordinary skill in performing a hip replacement procedure: Wallace v Kam [2013] HCA 19, at [8], following Rogers v Whitaker [1992] HCA 58; (1992) 175 CLR 479, at [14], p 489. 253Dr O'Carrigan's duty in that regard extended to ensuring that when operating on her left hip he would adhere to accepted protocols and checking procedures so as to be able to recognise and avoid foreseeable complications such as leg lengthening where it was reasonably possible to do so. The scope and content of that duty did not extend to a guarantee that the operation would be successful as "... Of all sciences medicine is one of the least exact": Thake v Maurice [1986] QB 644, at p 688. The practise of the surgeon's art should not be seen as being an exception to that statement. 254The second such matter is the factual evidence given by Dr O'Carrigan that comprised the sequencing and the detail of the intra-operative steps of the first procedure he performed, had not been contradicted by other evidence. It can therefore be accepted that the sequential details of that procedure were as stated by Dr O'Carrigan. 255The third such matter is, notwithstanding that within the operating theatre at the time of the first procedure, Dr O'Carrigan had the surgical assistance of Dr Michael Solomon, a senior colleague and mentor, as the operating surgeon, Dr O'Carrigan was solely responsible for any intra-operative judgments, decisions and actions that were made and implemented in the course of that operation. Dr O'Carrigan acknowledged this in his evidence. 256The relevance of that matter is that a submission was made on behalf of the plaintiff that was critical of the fact that Dr Solomon was not called by the defence to give evidence in the proceedings. In my view, that submission can have no force as no relevant challenge was made to the evidence of Dr O'Carrigan so as to raise the spectre that evidence from Dr Solomon, corroborative or otherwise, was required on any matter of fact on which Dr O'Carrigan gave evidence. 257If the plaintiff's case was based on a proposition that the required operation protocols were not adhered to or not correctly applied by Dr O'Carrigan, then this would be something that could be sought to be proven either by calling a witness to attest to such facts, or to rely on admissions and inferences. The plaintiff's case proceeded upon the latter basis. 258The fourth such matter is that, although in his evidence Dr O'Carrigan, conceded in hindsight he had made an intra-operative error of judgment in selecting a size 2 femoral stem prosthesis and this had resulted in the plaintiff suffering a leg length discrepancy, his concession in that regard, without more, does not necessarily amount to an admission of, or a proper basis for a finding of, negligence on his part: Vairy v Wyong Shire Council. 259The fifth such matter is that Dr O'Carrigan's judgment, later conceded by him in hindsight to have been erroneous, was made in the clinical setting by a process of reasoning and judgment, including by testing, which involved subjective "feel" based upon his experience, and was not simply an accidental or mistaken selection of a piece of surgical hardware thought to be size 1 but which was in fact size 2. An error of the latter variety gives rise to an entirely different analysis. 260The sixth such matter is that it was common ground amongst the experts that leg length discrepancy was a foreseeable consequence of total hip replacement surgery. It was also common ground that leg lengthening as a complication of hip replacement surgery can happen in the best of hands with all due precautions having been taken. 261When the plaintiff gave her consent to having the first procedure she was warned that leg lengthening could occur as a possible complication of the surgery. The significance of this is that the occurrence of leg lengthening following hip replacement surgery, without more, does not necessarily and of itself require a finding of negligence: s 5B(1) of the CL Act. The suggestion that the error in question could have been avoided by the exercise of reasonable skill and care, and a finding on the balance of probabilities that there had been a failure to apply reasonable skill and care, involve different levels of satisfaction. 262In those circumstances, for there to be a finding of negligence, it is first necessary to identify the occurrence of one or more sentinel events or turning points that either occurred or could reasonably be inferred to have occurred during the surgery, and that such event or events had foreseeably given rise to the opportunity for the error to occur. 263The subsidiary task is to then determine whether, but for the failure to exercise the required standard of reasonable surgical skill and care, that error had occurred: s 5D of the CL Act. 264In looking to the expert evidence tendered in the proceedings in respect of the first procedure, and reducing that evidence to its essentials without diminishing its force by restatement in more simplified terms, the evidence in favour of a finding of an intra-operative breach of duty of care on the part of Dr O'Carrigan seems to be based on the following constructed propositions that emerged from the concurrent expert evidence: The expected surgical result (a)The expectation is that the operating surgeon will make the right choice of prosthetic femoral stem size, where experience shows that most operators manage to achieve the desired result most of the time, and if the correct intra-operative sequences are followed and the wrong sized stem is found to have been fitted, this is suggestive of intra-operative error in the application of the checking sequences: Dr Sullivan; Hindsight analysis or prospective / retrospective equivalence (b)On behalf of the plaintiff it was argued that the conclusion arrived at retrospectively by Dr Sullivan to the effect that Dr O'Carrigan should have decided to fit the smaller or size 1 femoral stem in the first procedure, as occurred in the remedial procedure, should also be determinative of what should have occurred in the course of the first procedure, even on a prospective analysis, as is required when following the instruction in Vairy v Wyong Shire Council; Remediable unacceptable result (c)Dr O'Carrigan's acknowledged error of judgment in the first procedure which resulted in the insertion of the wrong sized femoral stem prosthesis was professionally unacceptable because of what was assumed by Dr Bracken to be recognisable palpable tissue and joint tightness, with inhibited flexion and abduction at the time of final intra-operative testing, which should have in turn led to a realisation that something was wrong and required immediate correction before completion of the first procedure, that being at a time when it was convenient and possible to remedy joint tightness (and by inference probable leg lengthening even though not perhaps recognisable at that time) without the need for the subsequent remedial procedure which was performed 6 weeks later: Dr Bracken. 265Shortly stated, the plaintiff's case was argued on the basis that the expected surgical result was not achieved, and that the unacceptable result that occurred as a consequence, was both recognisable and remediable at the time of the first surgery. 266In my view, there is a flaw in the analysis advanced on behalf of the plaintiff in that it relies upon an impermissible hindsight analysis, and in so doing, it seeks to draw an unacceptable equivalence between the retrospective recognition of intra-operative error and the prospective analysis of the facts, as is required by Vairy v Wyong Shire Council. 267In my view, no intra-operative sentinel event involving foreseeable and avoidable error has been identified, either in the factual description in the operation note, hospital notes or correspondence from Dr O'Carrigan, nor in the oral evidence of Dr O'Carrigan, that would reasonably support a finding of negligence. 268The highest the case for the plaintiff can be put is that at the time of the first operation when Dr O'Carrigan made the wrong intra-operative judgment that the size 2 femoral test stem was the appropriate size and that it had been placed in what he considered to be the correct position of insertion sufficiently down the canal of the femur, and when he then tested the fit and the tension in hip joint and surrounding tissue structures, he was said to have made incorrect judgments that could have been avoided if he had exercised reasonable skill and care. 269To succeed on that case, the plaintiff must rely upon the radiological evidence, available inferences reasonably drawn from the known facts, and from the expert evidence. 270The relevant known facts are that the plaintiff's actual or true left leg lengthening, unaffected by postural adjustment, was measured at re-operation at 1cm. This discrepancy was corrected at re-operation when the size 2 femoral stem was substituted with a size 1 femoral stem. Of itself, a discrepancy of that measurement did not bespeak negligence. 271The hindsight concession of error of judgment by Dr O'Carrigan on those facts can be excluded from this analysis because that concession was only made in hindsight: Vairy v Wyong Shire Council. 272No inference of negligence could reasonably arise from the later remedial procedure which ended up being completed by using a posterior approach as distinct from the earlier anterior approach, and where placement of the prosthesis on the posterior approach could be checked by measurements using a hip calibrator: s 5C(c) of the CL Act. 273The expert evidence in support of the proposition that the erroneous placement of the size 2 stem ought to have been recognisable by Dr O'Carrigan before he completed the operation, was in the form of an assumption based inference raised by Dr Bracken. That argument was to the effect that when Dr O'Carrigan tested the prosthesis and the surrounding tissues before wound closure, he ought to have felt that the hip was tight and that the surrounding tissues were incorrectly tensioned, that flexion was inhibited and that there was abduction, thereby indicating an incorrect adjustment or fit of the prosthesis, which required remedial action before completion of the procedure and wound closure. 274The difficulty with acceptance of the underlying assumptions for that proposition is that those underlying factual matters were not accepted by Dr O'Carrigan, and his denial was neither inherently improbable, nor were his denials controverted by other evidence. 275Furthermore, the arguments based on assumptions from Dr Bracken's evidence regarding soft tissue tension pay no regard to the technical difficulties referred to by Dr O'Carrigan in his evidence at T131.6 - T131.46 which are cited at paragraph [140] above concerning the importance to the analysis of the difficulty with feedback regarding the assessment of soft tissue tension following traction release when using the anterior approach as distinct from the posterior approach. 276The plaintiff's case in respect of the first procedure, which required the drawing of the submitted inferences, is problematic on that evidence. 277In general, there are some cases where inferences based on assumptions can trump a denial of the assumed matters. However, for acceptance, such cases require that the assumptions themselves be compellingly supported by the facts as being incontrovertible, but that is not the case here. 278In my assessment, the factual foundations for the proposition that there was or must have been palpable hip tightness, inhibited hip flexion, inappropriate soft tissue tension and abduction of the left leg, was not supported by the evidence. That is not a criticism of Dr Bracken. He applied his analysis to the facts as they were presented to him, and he then tried to identify a reasonable hypothesis that might serve to explain the plaintiff's post-operative leg lengthening, hence his assumption. 279Dr Bracken's hypothesis must be considered in the light of the evidence in order to determine whether there is a reasonable basis, other than unsupported assumption, for finding that the elements he had assumed to have been present, were in fact present. 280The material given to Dr Bracken did not include the detail of the evidence Dr O'Carrigan gave in the proceedings, which is summarised at paragraphs [93] to [100] and [121] to [147] above, and it did not include the detail or the substance of Dr O'Carrigan's thought processes and actions on those matters, which might have otherwise been available for consideration if, for example, there had been answers to interrogatories directed at those matters. 281Whether or not the assumptions and related inferences within the hypothesis raised by Dr Bracken were soundly based so as to justify the inferences and findings sought on behalf of the plaintiff, is a question that must be evaluated in the light of the explanatory discussion that occurred when the experts gave their evidence concurrently. 282When the concurrent evidence of the experts is examined it becomes plain that the following matters are determinative, and preclude acceptance of the assumptions relied upon by the plaintiff: (a)The experts have agreed that leg lengthening following hip replacement surgery can occur without there having been a departure from accepted standards of practice. In those circumstances, where leg lengthening has occurred, without evidence or compelling inference of an identified departure from the expected standard of care, the plaintiff's case cannot succeed. A surgical result that is less satisfactory than was expected, does not necessarily equate with negligence; (b)Evidence is required to contradict the appropriateness of Dr O'Carrigan's judgment that in the first procedure, after undertaking sequential broaching of the femur, he determined that a size 2 femoral stem was the appropriate means of achieving stability of the prosthetic femoral stem for weight bearing. In the context of the whole of the evidence, Dr O'Carrigan's hindsight concession of an error of judgment in the selection of femoral stem size is an insufficient basis to satisfy that evidentiary requirement for proof of negligence; (c)Evidence is required to contradict the appropriateness or Dr O'Carrigan's assessment of the "feel" of the final fit of the prosthetic implants. Evidence along those lines was not called; (d)Dr O'Carrigan's duty was to exercise reasonable skill and care in carrying out the procedure. That duty did not extend to a duty not to make mistakes that were unavoidable whilst taking intra-operative decisions and actions; (e)The description given in the evidence of the process by which the surgeon identifies relevant anatomical landmarks, not necessarily by sight, during surgery, and then works towards selecting and fitting a prosthetic femoral stem, does not connote a process of precision. Instead, as the evidence indicates, the process involves tolerance for variations. Accordingly, an outcome whereby an actual 1cm leg length discrepancy has occurred does not necessarily have to be considered to be unacceptable or as falling outside the parameters of what would be expected to have resulted from competently performed hip replacement surgery. 283The key points of difference in the evidence as to whether, at the end of the first procedure, the plaintiff's hip was palpably tight, with inhibited flexion and inappropriate abduction involves a divergence between the assumption based evidence of Dr Bracken on the one hand, and the factual evidence of Dr O'Carrigan on the other, as that latter evidence was supported by the evidence of Dr Sullivan. 284Those divergences of opinion are not resolved by applying the weight of numbers, and they must be determined by an analysis of the underlying reasons for those points of difference. 285On one side of the analysis, Dr Bracken's evidence proceeded on the assumption that intra-operatively, the plaintiff's left hip must have been tight with palpable inhibited flexion, incorrect tissue tension and with the leg in abduction. There was no factual evidence to support those propositions. 286Dr Bracken arrived at that assumption based on his own experience of performing hip replacement surgery on over 1000 occasions, including by use of the anterior approach. However, this was in circumstances where his experience did not involve use of the traction table or a traction boot. These were devices which, according to the evidence, were released to a degree for testing purposes, but nevertheless necessarily inhibited the range of intra-operative leg movement that could be obtained to manually test the hip and the associated soft tissues before surgical closure. 287I consider this factor to be a matter of some importance because Dr Bracken referred to the intra-operative process for testing the result of the operation and assessing the range of hip movement as if there were no restrictions on such testing, drawing upon his own experience of hip replacement surgery, which he last performed about 20 years ago. That evidence was given in the context where he had no experience in the use of the specific Medacta prosthetic hip system that had been used by Dr O'Carrigan in this instance. There was no evidence that would reasonably permit an assumption that all prosthetic hip systems were the same. 288Doubts and reservations therefore arise as to the validity of Dr Bracken's assumptions as to hip tightness and the related assumptions he invoked as being observations available to be made by Dr O'Carrigan during the first procedure. 289On the other hand, Dr Sullivan, who has in fact used the Medacta prosthetic system, and whose orthopaedic opinions concerning hip replacement surgery were founded upon experience from current practise, described limitations in the testing of hips intra-operatively when using the anterior approach due to the traction boot and the particular operative position that was necessarily required when using the anterior approach to such surgery: T193.40. 290In that analysis, for the above reasons, where differences of opinion have arisen in the evidence on what Dr O'Carrigan ought to have detected on intra-operative testing of the plaintiff's left hip, I prefer the factual evidence of Dr O'Carrigan to the effect that when he "felt" and assessed the results of his surgery, there were no such problems detected. 291I also prefer the opinion evidence of Dr Sullivan to the assumptions made by Dr Bracken because Dr Sullivan's evidence was based on current practise and experience using the Medacta system. I am reinforced in that view especially where Dr O'Carrigan's evidence on the key aspects of intra-operative events was not materially challenged. 292In my view, on the foregoing analysis, the evidence and arguments in the case for the plaintiff have not identified any sentinel turning point or points during the first procedure that serve to reliably show that on the balance of probabilities Dr O'Carrigan had, by his intra-operative judgments, decisions and actions, when viewed prospectively, departed from the standard of reasonable care that was expected of him as an orthopaedic surgeon in the circumstances in which he operated on the plaintiff on 2 August 2011. 293In viewing these conclusions through the prism of s 5B of the CL Act, whilst the requirements of s 5B(1) concerning foreseeability and significance of risk and the need for precautions against risk are satisfied, the requirements of s 5B(2), the need to show that the leg lengthening in question could more probably than not have been avoided if reasonable skill and care had been exercised, have not been established: s 5D of the CL Act. 294Accordingly, I am compelled to find that Dr O'Carrigan was not negligent in the performance of the first procedure which resulted in a 1cm lengthening of the plaintiff's left leg.

Issue 2 - Alleged negligence concerning timing of second procedure 295When Dr O'Carrigan gave consideration to the plaintiff's need for revisionary surgery, and the timing of that surgery, the duty of care he owed required that he take reasonable care to provide her with the appropriate professional advice for the purpose of her deciding which option she should take from the range of treatment options available for the management of her leg lengthening which was of concern to her: Rogers v Whitaker [1992] HCA 58; (1992) 175 CLR 479 at [5], p 483. 296In the course of discharging that duty of care, Dr O'Carrigan provided the plaintiff with his considered advice on the risks and benefits of either an early operation, or a delayed operation. That advice was summarised in the consent form prepared by Dr O'Carrigan, and which identified the range of those options as being to watch and wait, which would risk incurring ongoing worsening problems according to the natural history of the condition, or to have revision surgery to shorten the affected leg: Exhibit "B", p 86. 297At paragraphs [182] to [190] above, I have reviewed the evidence comprising Dr O'Carrigan's reasoning that lay behind the clinical judgment he made in favour of recommending to the plaintiff that she have early revision surgery 6 weeks following the first procedure. 298Essentially, Dr O'Carrigan's reasoning was that if the leg lengthening was not corrected at that time rather than waiting for 12 months, the plaintiff faced worsening pain and distress, and since she was not adjusting well to her leg length discrepancy, and because there was pelvic significant tilting with contractures, 6 weeks was an adequate period to have waited to see if accommodation was going to occur, and to leave the operation for a longer period of time would risk worsening of pain leading to chronic pain. In addition, due to the nature of the healing process involving bony growth into the prosthesis, a delayed operation would involve greater scope for risk and complications as osteotomy would be required to split and then reassemble the femur around the prosthetic stem. 299Dr O'Carrigan's reasons as identified above were not fundamentally contradicted by other expert evidence. 300At paragraphs [231] to [232] above I have reviewed the expert evidence that set out the arguments both for and against revisionary surgery at the 6-week stage. 301Essentially, the timing of the second operation was dependent upon an assessment of reasonableness of the judgments made by Dr O'Carrigan as the treating orthopaedic surgeon as to whether, why, and when, revisionary surgery was indicated. 302As to the questions of whether and why revisionary surgery was required, the plaintiff made it plain to Dr O'Carrigan that she was concerned about her leg lengthening, and that she was also concerned about having to wear a built-up shoe. Dr O'Carrigan had also been made aware that the plaintiff was upset by the leg length discrepancy, and that it was causing her discomfort and inconvenience in her day-to-day life. 303In my view, based on the cited evidence given by Dr O'Carrigan and the evidence given by the expert witnesses, those reasons seem to be an adequate and appropriate basis for him to have recommended revision surgery to the plaintiff. 304This leaves the question of the appropriate timing for the revision surgery to take place. This question must be resolved by reference to the evidence of Dr O'Carrigan and the expert evidence as it involves consideration of issues that are within the remit of the experts. 305I consider that in this case, the criticism by experts of the timing of the revisionary surgery involves a process of second-guessing the clinical judgments that Dr O'Carrigan made at the time. It is therefore necessary to review the pathway by which that professional criticism unfolded concerning Dr O'Carrigan's advice as to timing of the operation. 306The starting point of that analysis is an acceptance of the proposition that Dr O'Carrigan's judgments under present review were made by him in accordance with his duty to ensure that at all times he acted with the best interests of his patient in mind: Sidaway v Board of Governors of Bethlem Royal Hospital & Maudsley Hospital [1985] UKHL 1; [1985] AC 871, at 904; Breen v Williams [1996] HCA 57; (1996-1997) 186 CLR 71, at 97, 105. 307In that regard, I do not accept the suggested criticism that was put to Dr O'Carrigan in cross-examination to the effect that he decided he would not investigate the plaintiff's leg lengthening on 8 August 2011, or soon thereafter, because, as it was suggested, he already knew that he had used the wrong sized femoral stem. Instead, I accept Dr O'Carrigan's forthright denial of that proposition: T163.48 - T164.10. I accept that at all times he acted in good faith and in the best interests of the plaintiff: T146.27. 308Since the criticisms of the timing of the revision surgery were the subject of debate amongst the experts, a decision on which body of opinion should be preferred, must be determined by rational analysis. 309In examining the basis of Dr Bracken's opinions that were critical of the timing of Dr O'Carrigan's revision surgery, it is of some relevance to observe that Dr Bracken's opinions had significantly changed over time. That is not necessarily a criticism of Dr Bracken, rather, it is simply a reflection of how on analysis, the nature of the issue under present consideration is such that reasonable minds may differ concerning the appropriate timing for revision surgery in this case. 310Dr Bracken's initial opinion, expressed in his report dated 12 April 2012 stated that the plaintiff's left leg lengthening had led to an intolerable situation, this in turn had led to a recommendation for a revision operation as soon as possible, and which, once carried out had led to a satisfactory outcome. Dr Conrad's report dated 20 November 2012 was essentially in similar terms to the report of Dr Bracken. 311Dr Sullivan's report dated 8 January 2013, in response to those opinions, stated that it was reasonable for Dr O'Carrigan to have allowed a small period of time to pass before performing the revision procedure to allow for some prospect of adjustment and also because earlier remedial surgery involved increased risk of infection. 312Both Dr Bracken and Dr Conrad had the opportunity of considering the report of Dr Sullivan. Dr Bracken ended up being in substantial agreement with Dr Sullivan, and thought that it was doubtful that the plaintiff's problem with leg lengthening would have settled down had Dr O'Carrigan waited for 12 months. In contrast, Dr Conrad thought that Dr O'Carrigan should have waited 12 months to allow natural adjustment to occur. He said that if revision surgery would have been delayed for that period, on the balance of probability, it would not have been needed. At the trial, against that latter view, Dr Sullivan explained the principle to the effect that patients should initially be encouraged not to have a revision, was based on the premise that the patient considered that discrepancy could be accommodated: T210.40. 313Shortly before the trial, Dr Bracken revised his first opinion and stated that if the plaintiff had been treated conservatively instead of re-operating early, there was a high probability that the revision operation may well not have been needed. That alteration in the opinion of Dr Bracken occurred without a change in his basal assumptions. Instead, his altered opinion was issued after a period of reflection and consideration of the views of the other experts. This indicates that if a meeting of experts had been arranged earlier, the areas of dispute may well have been narrowed, if not resolved. 314In weighing the factors for and against early revision surgery, as respectively listed at sub-paragraphs (a) and (b) of paragraph [231] above, in my assessment of the evidence, the pivotal factors that are determinative on the issue of the timing of the revision surgery are firstly, the position of advantage that Dr O'Carrigan occupied as the treating surgeon assessing the indications for early intervention as opposed to delaying a revision, and secondly, in conjunction with that factor, Dr O'Carrigan's own assessment of the plaintiff's coping ability, and her emotional reaction to living with her acquired leg lengthening problems. 315In that weighing exercise, I consider that some significant credence and weight must also be given to the views of Dr O'Carrigan as to how and why he was going to manage the particular problem, including when revision should be suggested to take place. Those judgments were contemporaneously reactive to the complaints the plaintiff made at the time, and it was not suggested that Dr O'Carrigan's observations concerning those matters were wrongly made. 316In those circumstances, the debate comes down to a matter of clinical judgment. In that regard, I prefer the evidence of Dr O'Carrigan and Dr Sullivan to that of Dr Bracken and Dr Conrad because Dr Bracken's initial opinions varied over time, and more importantly, all experts agreed it was most important that a clinical assessment be made as to how the patient was coping with the leg length discrepancy: T209.25 - T209.43. 317In that regard Dr O'Carrigan carried out that clinical assessment, which was to the effect that the plaintiff was not coping and was not likely to adjust to the discrepancy over time. That assessment was not contradicted as being wrong or improbable. The plaintiff was concerned to correct the problem and was anxious about it. That was the clinical impression she gave Dr O'Carrigan and he recounted that impression in his evidence concerning those events. That evidence was not contradicted by any evidence in reply, either from Ms Lange, her partner, her daughter or her parents, all of whom were present at the critical consultation with Dr O'Carrigan on 23 September 2011. 318Dr O'Carrigan was the practitioner who had the relevant discussion with his patient, and he was the one who had to assess and weigh the apparent significance to his patient of her ongoing symptoms, her reaction in having to live with leg lengthening and the problems this was causing her, including her emotional reaction to those problems. 319Those matters required clinical judgment. I am not persuaded that Dr O'Carrigan's clinical judgment has been shown to be wrong. 320I am reinforced in that view by the opinion of Dr Sullivan, which supported Dr O'Carrigan's judgment, and because Dr Bracken conceded that the critical judgment as to whether it was likely that the patient would posturally cope over time was a judgment to be made by the surgeon on the evidence before him: T209.42 - T209.47. 321I therefore find that Dr O'Carrigan had acted in accordance with the requirements of reasonable skill and care for a practitioner in his situation when he recommended to the plaintiff that she have revision surgery on 23 September 2011, 6 weeks after the first procedure. He did so after considering the physical, functional and psychological issues affecting the plaintiff, and after he had taken time to make expert measurements on the x-rays, weigh the options, and cogently reason that it was preferable to operate earlier rather than to risk increased disability and complications in a delayed revision operation. 322In those circumstances, the reasons of the treating clinician should not be discounted and second-guessed lightly from the leisurely vantage point of hindsight where the patient was properly informed of, and was appropriately guided through, the available management options, and chose accordingly. 323Against that proposition, none of the factors within the expert evidence and which are summarised at sub-paragraph (a) of paragraph [231] above, and which are against early intervention, involve absolute statements that require rejection of the reasons given by Dr O'Carrigan as summarised in paragraphs [182] to [190] above, in justification for the early revision surgery. 324I therefore find that the evidence does not satisfy the requirements of s 5B of the CL Act, particularly s 5B(c) concerning the precautions that ought to have been taken by a reasonable person in the position of Dr O'Carrigan. There is no reasonable basis from within the evidence adduced to support a finding of breach of duty of care and negligence concerning the timing of the revision surgery.

Issue 3 - Defence invoking s 5O of the Civil Liability Act 2002 325In case I be wrong in my conclusions concerning Issue 1 and Issue 2, I will proceed to deal with the pleaded defence that invokes s 5O of the CL Act, as well as setting out my assessment of the damages the plaintiff would otherwise have been awarded if, contrary to my liability findings, she had been successful in her claim. 326In order to successfully invoke a defence founded upon s 5O of the CL Act, Dr O'Carrigan carried the onus of showing that he should not incur a professional liability due to negligence on his part because at the relevant time, he had acted in a manner that was widely accepted in Australia by peer professional opinion as competent professional practice: s 5O(1) of the CL Act: Halvorsen v Dobler [2006] NSWSC 1307; Dobler v Halvorsen [2007] NSWCA 335. 327In a consideration of a defence based upon s 5O(1), irrational peer professional opinion cannot be relied upon to support such a defence: s 5O(2) of the CL Act. 328A defence based on widely accepted peer opinion may be upheld even where peer professional opinions in question may differ (s 5O(3) of the CL Act) and where a particular opinion is not universally accepted: s 5O(4) of the CL Act. 329The relevant peer professional opinion relied upon by Dr O'Carrigan in this case is that of Dr Sullivan. 330In respect of the first procedure, Dr Sullivan was of the opinion it was generally accepted amongst orthopaedic surgeons that none of the techniques for attempting to restore anatomy, leg length and offset were infallible, and at this stage of development of the art of total hip replacement surgery, it was not yet possible to completely eliminate leg length discrepancy following total hip replacement surgery, noting that all techniques had their drawbacks: report of Dr Sullivan, 18 January 2013. 331The experts also agreed that the phenomenon of leg length discrepancy sometimes occurs despite all the required steps of precaution having been carried out even in the most expert hands: Dr Sullivan T186.35 - T186.40; Dr Bracken T189.49; all experts T189.50 - T191.10. 332In his supplementary report dated 3 April 2013, Dr Bracken stated that he was in general agreement with everything Dr Sullivan had to say in his report. Therefore, in light of the terms s 5O of the CL Act, for the purposes of identifying peer opinion within the scope of that section, it would appear to be unnecessary to go to Dr Conrad's opinion on the question of competent peer professional practice in Australia. This is because the evidence that I have cited clearly indicates that the defence claimed under s 5O of the CL Act, has been satisfactorily established in respect of the first procedure. 333In respect of the timing of the second procedure, Dr Sullivan was of the opinion that a revision at 6 weeks incurred less risk of significant complications (T187.15), and the timing of such a revision was a judgment call to be made by the treating surgeon (T213.43 - T213.48) in circumstances where Dr O'Carrigan had the requisite skill and experience to make that judgment (T214.24 - T214.28) and there were no absolute considerations for taking an alternative wait and see approach in the hope that postural accommodation would occur, especially where there was a concern over the ability of the patient to cope (T214.30 - T214.46). 334The opinion of Dr Sullivan as cited above in respect of the timing of the revision procedure was not irrational, as is evident from that summary of his views. 335The fact that in contrast, Dr Conrad considered it was preferable to undertake frequent reviews of the leg discrepancy over time before deciding to operate (T215.30 - T215.41) is not determinative in circumstances where the patient's concerns had to be addressed in light of her ability to cope with the discrepancy, a pressing matter which Dr O'Carrigan had to deal with at the time. Dr O'Carrigan gave cogent reasons for the position he took in that regard, and those reasons were supported by rational peer opinion as cited above. 336Dr Bracken's assumption to the effect that Dr O'Carrigan "had a bit of a panic" when he decided on the timing of his recommendation for the revision procedure, does not accord with my assessment of Dr O'Carrigan's evidence or the assessment of the evidence of the plaintiff on that matter, especially where a judgment had to be made on whether the plaintiff was likely to accommodate the problem: Dr Bracken: T218.17. 337In that regard, Dr O'Carrigan made a judgment call based on the particular animated clinical situation that he had before him. Dr Bracken's comment based on an assumption that Dr O'Carrigan "had a bit of a panic" was based on his "impression". In my view, in such circumstances, the considered judgment of the treating surgeon should not be trumped by a hindsight "impression" gained by a medico-legal reviewer where there is room for reasoned and not irrational disagreement amongst peers. 338Overarching all of the evidence on timing was Dr Sullivan's opinion that if Dr O'Carrigan had formed the view that the plaintiff was unlikely to cope with post-operative leg discrepancy, a view that was clinically open for him to form in the circumstances, then it was reasonable for him to have offered the plaintiff the remedial surgery when he did: Dr Sullivan: T218.34 - T218.37. 339It follows that Dr Sullivan's reasons in respect of each procedure were not irrational and can therefore be taken to represent relevant peer professional opinion as to what constituted competent professional practice in Australia: s 5(O)(1) of the CL Act. 340In those circumstances, where it has not been shown that the relevant opinions of Dr Sullivan were unsupported by cogent reasons, then those opinions should not be characterised as being in any way irrational. 341Accordingly, Dr O'Carrigan must succeed in his defence that invokes s 5O of the CL Act.

Issue 4 - Assessment of damages 342In case I be wrong in respect of my liability findings, for the purpose of any reconsideration of the matter on an appeal, in the paragraphs that follow, after identifying the plaintiff's probable statistical life span, I set out my assessment of the plaintiff's damages claim.

Plaintiff's probable life span 343In assessing the plaintiff's damages, there is nothing that reasonably arises from the evidence to suggest that the usual statistical median life span would not apply to the plaintiff's circumstances. At the age of 48 years, the plaintiff has a rounded down probable median statistical life span of a remaining 40 years. For the purposes of assessing some of the claimed future losses, the undiscounted 5 per cent multiplier for 40 years is 917.5. The plaintiff has a remaining working life of 19 years. The undiscounted 5 per cent multiplier for 19 years is 549.3.

Non-economic loss 344On behalf of the plaintiff it was submitted that her damages for non-economic loss should be assessed at $187,500, which is the equivalent of 35 per cent of a most extreme case according to the provisions of s 16 of the CL Act. 345In contrast, on behalf of the defendant it was submitted that those damages should be assessed as being no more than $75,000, this being the equivalent of 28 per cent of a most extreme case. 346It was argued that the plaintiff's functional capacity has improved from that which prevailed before the first operation and that the plaintiff's economic capacity had recovered to that which prevailed before that surgery. It was also argued that the plaintiff's demeanour, her care over her appearance, her interest in social activities and her motivation to work are inconsistent with the existence of a significant psychiatric problem. 347The assessment of the physical component of the damages for non-economic loss poses difficulties because from a functional point of view, Dr Brightman was unable to identify the difference between the plaintiff's pre-operative condition, her post-surgical condition, or the effects of the two operations: Exhibit "B", pages 13 and 14. 348Nevertheless, the plaintiff has acquired additional scarring, and has had a harrowing experience as a result of the leg lengthening and the need for a later remedial operation. She has also been left with some significant psychological consequences including depression and anxiety. 349In assessing this head of damage, I have had regard to my findings at paragraphs [210] to [213] concerning the plaintiff's injuries and her related disabilities. Those disabilities have had, and will continue to have, a significant and deleterious impact on the plaintiff's enjoyment of the amenity of her life. In those circumstances, I consider that the appropriate assessment of non-economic loss would be 29 per cent of an extreme case pursuant to s 16 of the CL Act, which is the equivalent of $96,500. 350If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for non-economic loss in the amount of $96,500.

Past economic loss 351On behalf of the plaintiff, it was submitted that her damages for past economic loss should be assessed in the sum of $36,000. This was said to have been based on an allowance of say 15 hours per week at $22 per hour net. 352In contrast, on behalf of the defendant, it was submitted that there has been no discernable difference between the loss of earnings that would have inevitably flowed from the first procedure, and for which there could be no claim for damages for loss of earnings, and the additional time taken by the plaintiff to recover from the second procedure, as there would have been substantial overlap of those two periods. 353In my view, save for an allowance for a confined number of additional weeks, the submission made on behalf of the defendant must be accepted as being largely correct. 354In those circumstances I consider that a reasonable allowance for past loss of earnings would be for 12 weeks at 15 hours per week at $22 per hour net. This amounts to the sum of $3960. 355If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for past economic loss in the amount of $3960.

Past loss of superannuation 356If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for past loss of superannuation on the basis of the conventional calculation of 11 per cent of past economic loss damages, which yields the amount of $435.

Future economic loss 357On behalf of the plaintiff it was submitted that her damages for future economic loss be assessed at 10 hours per week at $22 per hour over the remaining 19 years of her working life, in the sum of $135,000. 358On behalf of the defendant it was submitted that this component of the claim made on behalf of the plaintiff was unreasonable, and that the maximum amount awardable should be of the order of $50,000. 359In my view the evidence does not permit the projection of a precise weekly sum over the remainder of the plaintiff's working life. Instead, I consider that a monetary buffer amount is the more appropriate method by which to compensate the plaintiff for her future loss of earning capacity: Penrith City Council v Parks [2004] NSWCA 201; State of NSW v Moss [2000] NSWCA 133, (2000) 54 NSWLR 536; Allianz Australia Insurance Ltd v Kerr [2012] NSWCA 13. 360I consider that any such buffer should be in a significant amount to reflect the likely difficulties the plaintiff continues to have with prolonged sitting and sedentary tasks. This would be likely to adversely affect her in the management role to which she aspires and is likely to achieve, as well as causing her difficulties with some tasks involving mobility and dexterity. She has difficulty lifting and has sustained pain in her leg afterwards. She is also disadvantaged on the labour market due to her additional restrictions. I consider that the appropriate buffer sum should be in the amount of $75,000. 361If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for future economic loss in the amount of $75,000.

Future loss of superannuation 362If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for future loss of superannuation, using the conventional assessment at 14.01 per cent of such damages. Accordingly, I would have assessed the claim for future loss of superannuation in the amount of $10,507.

Past domestic assistance 363On behalf of the plaintiff it was submitted that the plaintiff should be awarded damages for past domestic assistance in the assessed sum of $10,000. 364In contrast, on behalf of the defendant it was submitted that no damages should be awarded for past domestic assistance because the evidence does not demonstrate that such assistance was needed and was provided for a minimum period of 6 hours per week for 6 months: s 15 of the CL Act. 365On the evidence it is difficult to differentiate the degree of domestic assistance required as a result of the second procedure alone. Although the plaintiff said she received about 8 hours per week of domestic help at the time of the hearing, the state of the evidence does not permit a differential assessment between the level of assistance that has resulted from the first procedure and that due solely to the effects of the second procedure. Without that differentiation, the essential requirements of s 15 of the CL Act cannot be satisfied. 366I therefore find that the submission made on behalf of the defendant is correct and it should be accepted. I would therefore have made no award of damages for past domestic assistance.

Future domestic assistance 367On behalf of the plaintiff, a claim was made for future paid domestic assistance in the amount of $100 per week, which is roughly equivalent to 4 hours per week at $26 per hour, over her probable life span, in the projected sum of $90,000. The restrictions imposed by s 15 of the CL Act do not apply to that claim. 368The plaintiff no longer does the gardening. She gets assistance with shopping. Her partner did some of the cleaning around the home before the first procedure. He works long hours and it would appear that he no longer provides as much assistance as he used to in the past. This head of damage is difficult to assess on the evidence. However, the claim of $100 per week, when seen as representing about 4 hours per week, seems reasonable, and I would allow that claim. 369The projection of $100 per week at the claimed rate of $26 per hour at 5 per cent over 40 years (x 917.50) for future paid care yields the undiscounted sum of $91,750. 370I consider that a projection of that kind should be discounted by 25 per cent for vicissitudes, including for the difficult to assess prospect that at least some of the plaintiff's future restrictions in respect of her domestic tasks would be due to the effects of the first procedure, for which there could be no claim for damages. After discount, this reduces the assessed amount to $68,812. 371If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for future domestic assistance in the amount of $68,812.

Future treatment expenses 372On behalf of the plaintiff it was submitted that the plaintiff's damages for future treatment expenses should be assessed in the amount of $45,000. 373In contrast, on behalf of the defendant, it was submitted that such damages should be assessed at no more than $2000. 374I consider it is likely that the plaintiff will incur some occasional future medical and allied expenses on an unpredictable basis. In view of the unpredictability of that expenditure, I consider that a modest buffer should be awarded in the amount of $5000. 375If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for future treatment expenses in the amount of $5000.

Past out-of-pocket expenses 376The parties ultimately reached agreement that the out-of-pocket expenses incurred by the plaintiff as a result of the second procedure were in the sum of $5226.75. If the plaintiff had been entitled to an award of damages I would have assessed the plaintiff's damages for past out-of-pocket expenses in the amount of $5226.75.

Summary of damages assessment 377My assessment of the plaintiff's damages is summarised as follows: (a) Non-economic loss $96,500 (b) Past economic loss $3,960 (c) Past loss of superannuation $435 (d) Future economic loss $75,000 (e) Future loss of superannuation $10,507 (f) Past domestic assistance $Nil (g) Future domestic assistance $68,812 (h) Future treatment expenses $5,000 (i) Past out-of-pocket expenses $5,226.75 Total $265,440.75

378If the plaintiff had been entitled to a verdict in her favour, damages would have been assessed in the amount of $265,440.75.

Disposition 379As the plaintiff's case has not been made out, the defendant is entitled to a verdict in his favour.

Costs 380As the defendant has been successful in the proceedings, he should have his costs paid by the plaintiff on the ordinary basis, unless otherwise ordered. This should be subject to the qualification that those costs should not include the costs associated with the expert witnesses giving their evidence concurrently. 381I have come to that conclusion because in their approach to the expert evidence the parties made no effort to convene or to seek an early order to convene a pre-hearing meeting of experts with a view to narrowing the scope of the dispute within the evidence of those experts, and to seek to facilitate agreement within the opinions of the experts. 382In my view, the nature of the issues calling for expert opinion in this case were readily amenable to such a course, as became readily apparent in the course of the oral evidence of those experts. I consider that if those experts had been properly guided in their tasks, within the spirit and application of s 56(3) of the CP Act, they most probably would have reached a position where they could have succinctly stated their respective agreements and disagreements in a short memorandum or report with supporting reasons. 383If the parties had approached the matter in that way in order to facilitate a just, quick and cheap disposition of the proceedings, or to at least narrow the issues at an early stage, it is very likely that oral evidence from the experts would have been considerably shortened, if not rendered unnecessary. 384Since in this case neither party sought to take such a course, either by consent, or in the absence of consent, by seeking an appropriate direction from the court at an interlocutory stage in the event of a dispute over the point, I consider that each party should have to bear their own costs of the concurrent expert evidence session.

Orders 385I make the following orders: (1)Application by defendant to amend defence to plead the materialisation of an inherent risk pursuant to s 5I of Civil Liability Act 2002 is dismissed; (2)The defendant is to pay the plaintiff's costs of the dismissed application; (3)Verdict and judgment for the defendant; (4)The plaintiff is to pay the defendant's costs of the proceedings on the ordinary basis unless otherwise ordered; (5)Each party is to bear their own costs associated with the expert evidence given concurrently by Dr Bracken, Dr Conrad and Dr Sullivan, such costs to include witness expenses and the cost of representation during the taking of that evidence; (6)The exhibits may be returned; (7)Liberty to apply on 7 days notice if further orders are required.

DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 04 October 2013