Evidence and issues in the proceeding
29 It is plainly neither necessary nor desirable to discuss the evidence and issues that emerged at trial in any great detail. That said, it is important to address that topic, if only to emphasise that the litigation involved considerable complexity and risk for the applicants and group members, both in relation to liability and the quantum of damages. While at an intuitive level the case against DePuy and Johnson & Johnson Medical may have appeared to be fairly straightforward and strong, it in fact gave rise to a number of complex factual and legal issues. The applicants were by no means assured of success, or complete success.
30 The applicants' case relied fairly heavily on data recorded by the Australian Orthopaedic Association in relation to the outcome of all hip replacements performed in Australia. That data revealed that ASR implants required earlier and more frequent revision than other hip replacement prostheses in their class. For example, in relation to complete hip replacements, the ASR implants had a revision rate at 7 years of 37.1 percent, whereas other comparable implants had a revision rate of 14 percent. There was also evidence of a similar high revision rate for ASR implants found in comparable registries overseas, in particular in the United Kingdom. The applicants also relied on evidence that revealed that DePuy's own internal health hazard evaluation led to its decision to initiate a worldwide recall of ASR implants in August 2010 because they were defective and could cause health problems.
31 The applicants contended that the grossly increased rate of revision in relation to the ASR implants, together with DePuy's decision to recall the ASR implants in 2010, was enough to demonstrate that the ASR implants were not fit for purpose and were not of merchantable quality. The applicants led evidence from a number of epidemiologists, biostatisticians and other witnesses in relation to the reliability of the revision data and the conclusions that could properly be drawn from it. Those witnesses included: Professor Ross Crawford, an orthopaedic surgeon and Professor of Orthopaedic Research and Queensland University of Technology; Professor Lyn March, Professor of Rheumatology and Musculoskeletal Epidemiology at the University of Sydney; Professor Kerrie Mengerson, Professor in the Science and Engineering Faculty at the Queensland University of Technology; and Professor Stephen Graves, a trained orthopaedic surgeon and director of the relevant registry at the Australian Orthopaedic Association.
32 The applicants also argued that if the evidence of the increased revision rates was not sufficient alone to establish liability under the Trade Practices Act, they were able to point to certain design defects which meant that the ASR implants had a susceptibility to wear and other processes which in turn increased the risk of revision. They led evidence from several bioengineering experts and orthopaedic surgeons to demonstrate that the particular design of the acetabular cup of the ASR implants increased the susceptibility of the implants to "edge loading", which in turn increased the risk of wear and poor clinical performance. The applicants led evidence from the following witnesses in relation to that aspect of their case: Professor Dennis Bobyn, an Emeritus Professor in the Departments of Surgery and Biomedical Engineering at McGill University; Professor John Medley, Professor in the Department of Mechanical and Mechatronics at the University of Waterloo; Dr Gregory Roger, Adjunct Associate Professor of Bioengineering at the University of Sydney; Dr Hugh English, an orthopaedic surgeon based in Brisbane; Dr John Ireland, an orthopaedic surgeon based in Sydney; Dr David Langton, an orthopaedic researcher who had carried out extensive research in relation to the performance of the ASR implants; and Dr Antoni Nargol, an orthopaedic surgeon. Professor Nicholas Athanous, Professor of Musculoskeletal Pathology at the University of Oxford gave evidence about the resulting increase in adverse tissue reactions as a result of increased wear in the metal on metal implants.
33 The applicants also relied on clinical evidence to support the statistical and engineering evidence. A number of the orthopaedic surgeons referred to earlier in the context of the epidemiological and statistical evidence expressed opinions which supported the use of registry data to demonstrate the increased rate of revision associated with the ASR implants. They noted, in particular, that it was unlikely that patient and surgical factors adversely affected the utility of the data. They also referred to various potentially problematic design features of the ASR implants. The clinical evidence included evidence from Dr John Mills, Mrs Stanford's treating surgeon, and Dr Bernard Zicat, Mr Dunsmore's treating surgeon.
34 In relation to causation and the quantum of damages, Mrs Stanford and Mr Dunsmore relied on their treating surgeons, as well as expert evidence from two physiotherapists, a rheumatologist, two neurosurgeons, a neurologist, two physicians in rehabilitation medicine, three occupational therapists, a psychiatrist, a forensic accountant and an architect. Both Mrs Stanford and Mr Dunsmore and their spouses also gave evidence concerning the way in which the surgery had impacted upon their quality of life.
35 Each aspect of the applicants' case on both liability and quantum was challenged by DePuy and Johnson & Johnson Medical. Detailed expert and other evidence which challenged, contradicted or otherwise impugned the applicants' case, was adduced.
36 In relation to the increased revision rates reported in registry data, DePuy and Johnson & Johnson Medical contested the utility of the registry data and argued that the increased revision rates reported in the data did not demonstrate that the ASR implants had any material defects. They contended, among other things, that the data was inconclusive; that there were limitations in the registry's methodology and other flaws in the data; that the reported revision rate for the ASR implants was inflated by a "learning curve" that affected surgeons implanting the devices; and that the revision rate for the ASR implants was affected by a "recall effect", whereby the revision decisions of patients and their surgeons were influenced by DePuy's recall of the ASR implants in August 2010. The evidence adduced by the respondents in relation to this aspect of the case included evidence from the following witnesses: Dr Michael Bailey, a biostatistician at Monash University; and Professor Val Gebski, Professor of Biostatistics and Research Methodology at the University of Sydney.
37 DePuy and Johnson and Johnson Medical also called evidence from several clinical experts that suggested that surgeons were influenced by the so-called "recall effect" and that this inflated the revision rates for the ASR implants. The witnesses relied on in respect of this issue included: Dr Michael Dixon, an orthopaedic surgeon based in Sydney; and Professor Keith Petrie, Professor of Health Psychology at the Faculty of Medicine and Health Sciences at the University of Auckland. DePuy also relied on evidence from Dr Cuckler, who maintained that the ASR implants did not perform any worse than comparable implants in the same class.
38 DePuy and Johnson & Johnson Medical also challenged the applicants' evidence concerning the design features of the ASR implants, in particular the alleged susceptibility to edge loading. They contended that the ASR implants were no more susceptible to edge loading than other implants in their class and that, in any event, there was no demonstrated correlation between edge loading and poor clinical performance. They also pointed to evidence that they contended established that the design of the ASR implants accorded with scientific knowledge at the time of supply, including the known risks with these types of implants. In relation to this aspect of their defence, DePuy and Johnson & Johnson Medical relied on evidence from the following experts: Dr John Cuckler, an orthopaedic surgeon based in the United States with particular expertise in hip and knee replacement, biomaterials research and implant design and development; Dr Avram Edidin, a biomedical engineer; Professor David Williams, an expert in biocompatibility; Mr Christopher Hunt, a bioengineer employed by DePuy; and Dr Graham Isaac, a Distinguished Engineering Fellow employed by DePuy.
39 In response to the applicants' negligence case, DePuy and Johnson & Johnson Medical called evidence from Ms Sally Hunter, the director of regulatory affairs at DePuy's Leeds office, in support of DePuy's case that it followed all relevant regulatory processes in relation to the supply of the ASR implants; and Dr Aran Maree, the Medical Director for Johnson & Johnson Medical in Australia at the time, in relation to the company's claimed adherence to regulatory and complaints investigation processes. DePuy and Johnson & Johnson Medical argued that the evidence showed that the ASR implants were extensively tested according to accepted testing standards at the time of supply.
40 In relation to quantum, DePuy and Johnson & Johnson Medical relied on evidence from a rehabilitation physician, a toxicologist, a vocational psychologist, a psychiatrist, and a quantity surveyor.
41 Aside from the difficult factual and evidential issues the subject of the evidence called by the parties, the litigation raised several legal issues, in particular in relation to the proper construction of s 74B and 74D of the Trade Practices Act. The main issue in relation to those sections was whether the question of merchantability and fitness for purpose should be approached on the basis of the state of scientific knowledge at the time of supply, or the knowledge at the time of trial.
42 The applicants argued that a product's fitness for purpose must be determined by reference to the actual performance of the product and the current state of knowledge, as opposed to a hypothetical inquiry into whether any defect was within the state of scientific knowledge at the time of supply. DePuy and Johnson & Johnson Medical contended, however, that it was necessary for the applicants to demonstrate that the ASR implants were not fit for purpose by reference to the state of knowledge at the time of supply. They argued that, for them to be liable, any identified defect must have been within the state of scientific knowledge at the time of supply. DePuy and Johnson & Johnson Medical claimed that the evidence showed that the design of the ASR implants accorded with the scientific knowledge at the time of supply, including the known risks associated with those types of implants.
43 There were also questions of law concerning causation. Those questions arose in the context of the applicants' case based on the registry data and the elevated revision rate in respect of the ASR implants. In simple terms, there was an issue about which party bore the evidentiary onus: did the applicants have the onus of proving that the increased revision rates were caused by a design feature or defect in the ASR implants; or in the circumstances, did DePuy and Johnson & Johnson Medical effectively bear the onus of showing that the statistically high revision rates were the result of "confounders", such as the recall effect, or patient and surgical factors unrelated to any design features of the ASR implants.
44 The divergent position of the parties was not limited to the question of liability. Difficult questions of fact and law also arose in relation to the assessment of damages. To give but one example, the assessment of general or non-economic damages in respect of the causes of action under the Trade Practices Act was governed by provisions in Div 3 Pt VIB of that Act (now the Competition and Consumer Act 2010 (Cth)). In the cases of the cause of action in negligence, however, each of the states and territories had different statutory regimes for the calculation of non-economic loss. A question arose as to which regime or regimes should be used to assess damages. As discussed later, the settlement scheme has in effect adopted the Commonwealth statutory regime for the purposes of the assessment of compensation payable under the scheme.
45 Needless to say, the parties were well apart on the quantum of damages. In closing submissions, Mrs Stanford submitted that her damages in respect of the Trade Practices Act causes of action should be assessed at $1,223,586, whereas DePuy and Johnson & Johnson Medical submitted that the damages were properly assessed as being $111,130. Mr Dunsmore submitted that his damages in respect of the Trade Practices Act causes of action were properly assessed at $886,138, whereas DePuy and Johnson & Johnson Medical contended that Mr Dunsmore was only entitled to damages assessed in the amount of $63,005. The parties were equally divided in respect of the assessment of damages in respect of the cause of action for negligence, though the amounts claimed for damages in respect of negligence were generally higher.
46 This short and highly simplified summary of the evidence and issues in the litigation serves to illustrate that the applicants and group members faced a number of factual and legal hurdles at the trial. They were by no means assured of success in respect of the common issues concerning liability. Nor could it confidently be asserted that, even if liability was established, damages would necessarily be assessed in the amounts contended by Mrs Stanford and Mr Dunsmore. The reasonableness of the proposed settlement must be considered in the context of the significant litigation risk faced by the applicants and group members in this difficult case.
47 The trial concluded on 26 June 2015. The trial judge reserved his judgment. In early October 2015 the legal representatives of the parties attended a mediation. It would appear that an agreement in principle to settle the proceedings was reached between the parties in late 2015 or early 2016. On 31 March 2016, the parties executed a Settlement Deed.