The DePuy Pinnacle metal on metal hip litigation - Kennedys represents successful defendant in landmark product liability group action

In a landmark group action ruling, running to 170 pages, the Honourable Mrs Justice Andrews DBE sitting in the High Court has ruled in favour of the defendant, DePuy, the manufacturer of the Pinnacle ULTAMET® metal on metal (MOM) hip replacement, finding that the product is not defective under the Consumer Protection Act 1987 (CPA).

The action tried the preliminary issues of defect and causation.

The group litigation incorporated over 300 claimants, and ended in a four month trial during which the court received evidence from over 40 witnesses, including 21 experts ranging from orthopaedics to engineering and behavioural psychology to statistics. This has resulted in a robust and authoritative judgment which clarifies the interpretation and application of the CPA.

Importantly, the court addressed the test for ‘defect’ under the CPA - the level of safety persons generally are entitled to expect of a product - in the context of a new product designed to improve on the previous generation of products.

The principles established in this judgment apply to all products used by consumers that come within the CPA. The decision will have significance for all manufacturers and distributors, not just those in the life sciences industry, as well as their insurers

Background

Conventional hip prostheses performed well in elderly and inactive patients but had a higher failure rate in younger and more active patients, predominantly due to the adverse biological consequences of component wear of polyethylene used in the bearing surface, leading to revision surgery. The ULTAMET® was one of a range of products developed by DePuy and manufacturers in the early 2000s that sought to improve durability by using alternative bearing materials, in this case MOM.

It emerged that revision rates of the new MOM bearings were reported as being higher than those of components using the other surfaces introduced contemporaneously. It was against this background that the claimants asserted that the ULTAMET® was not safe.

The law

This case was brought under the CPA’s “no fault” liability regime.

Under the CPA, a producer is liable for injury caused by a defective product. A product is defective if it is not as safe as the public generally are entitled to expect in all the circumstances.

The test to establish defect under the CPA is necessarily broad, given that it has to cover a very wide range of products from bottle tops and toys to pharmaceuticals. Complexities therefore arise because of its broad formulation, but the judgment emphasised that a lack of safety was the hallmark of whether a product was “defective” under the CPA.

Can a known and inherent characteristic be a defect?

• The court was asked a novel question, which was the basis of the claimants’ primary case on defect: whether a known and inherent characteristic of a product could in and of itself be a defect. Here that characteristic was the tendency of the product to produce metal wear debris which might cause an adverse reaction in some patients giving rise to replacement revision surgery.
• The defendant argued that a known consequence of the ordinary use of the product could not amount to a defect. Applying the claimants’ logic to this case would render all hip implants defective under the CPA, as material loss produced by the wear of the implants occurs in all types of hip implants (whatever their bearing surface: metal or polyethylene) with the potential to cause an adverse reaction.
• The judge agreed with the defendant and went so far as to assess this aspect of the claimants’ case as being “untenable”.

The benefit of hindsight?

• In the alternative, the claimants argued that the ULTAMET® had an “abnormal” potential for damage, in the form of a materially increased risk of an adverse reaction to the metal debris.
• The main thrust of their argument was reliance on data which they asserted showed that ULTAMET® performed less well than other non-MOM prostheses which were introduced at the same time as, or even after, the ULTAMET®. This inevitably introduced an element of hindsight to the legal assessment of what the public expected in the early 2000s when ULTAMET® was placed onto the market.
• The court took a common sense approach and directed that hindsight has no place in the formulation of the expectation of safety.
• The fact that other products introduced at the same time or later may turn out to perform better is not an appropriate benchmark.
• The court determined that the correct comparator was one which would have informed public expectation at the time the ULTAMET® was introduced, i.e. an established prosthesis which was already on the market at that time.
• The court found that ULTAMET® did as well as or better than established prostheses and there was no material increase in the risk of harm by reference to this comparator. Accordingly, the ULTAMET® was not unsafe.

It is also noteworthy that in her judgment, Andrews J expressed her view that the ULTAMET® “was a well-designed product with many positive engineering features” and that confounding factors artificially increased the ULTAMET® revision rates. The judge expressly referred to “the panic about MoM (metal on metal) hips that was engendered in consequence of the increasingly hysterical media reporting”. This reporting, according to the judge, typically contained no scientific research to support alarmist contentions, which may have led patients to seek surgical revision and influenced surgeons’ willingness to revise.

It is not yet known whether the claimants will appeal the decision.

Impact

This decision is binding on all claimants who were part of the group litigation. It is also likely to provide some influential guidance to claims against manufacturers of other MOM hip implants not only in England and Wales, but also in Europe and around the globe.

More generally, the judgment will provide manufacturers of products with some confidence that the courts will take into account the benefits of a product and the avoidability or otherwise of the risks inherent in certain products.

Given its decision that the safety of new products should be compared to products existing at the time they are introduced to the market, the court’s interpretation of the CPA should not discourage the development of new, potentially life enhancing, technologies in the future, as might have been the case if the claimants’ arguments had succeeded.

Kennedys acted for the successful defendant manufacturer, DePuy.

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Read other items in the London Market Brief - May 2018