We have been following the story of the metal on metal (MoM) hip implant claims in the UK courts, with our last update in December 2017. A key ruling by Mrs Justice Andrews DBE in Colin Gee & Others v DePuy International Limited provides a further chapter in the MoM story, and brings welcome news for device manufacturers and their insurers.
MoM: a brief synopsis
As we explained in our December update, MoM hip implants were introduced in the late 1990s as the latest generation of hip implants. Their unique feature was that both the head and socket were made from metal (a cobalt/chromium alloy). They were thought to be more durable than existing models, and as a result more suitable for younger patients. They were also thought to present a lower risk of dislocation because they often had a larger head.
Following increasing concern about soft tissue damage to MoM patients, the Medicines and Healthcare products Regulatory Authority (MHRA) issued a number of guidance notes concerning MoM patients and specifically, the further investigations required to determine if revision procedures should be undertaken to avoid damage. This in turn led to litigation against the MoM product manufacturers for the provision of allegedly defective products.
DePuy: claims by 312 patients
312 patients brought claims against DePuy. Following a Group Litigation Order in July 2014, six lead claimants were identified and the position of each is analysed in detail in the judgment.
Although DePuy was the only defendant in this case, as reported in December, claims have been brought against most, if not all, manufacturers of MoM prostheses. On the whole, those actions and related negotiations have then been stayed pending the outcome of the DePuy Litigation. As Mrs Justice Andrews DBE states in her approved press summary “Although the findings of the court are not binding on parties to those other proceedings, it is hoped that they will provide them with guidance”. The true impact of the ruling is therefore likely to extend well beyond this manufacturer and group of patients .
DePuy: was the MoM implant defective?
This was a trial of a preliminary issue. The court’s task was limited to determining one question, namely: “whether or not the defendant is liable to the claimant, subject to any development risk defence”. As the 762 paragraphs of Mrs Justice Andrews DBE’s judgment illustrate, reaching the answer was not straightforward.
The court had to determine whether or not the DePuy implant failed to meet the standard of safety that the public generally was entitled to expect at the time when the product was introduced to the market, such that it would be considered ‘defective’ for the purposes of section 3 of the Consumer Protection Act 1987.
The claimant patients argued that DePuy’s implant did fall short of the required standard. The “tendency or propensity” for damage constituted a defect, and the inherent potential for damage was sufficient.
That approach was robustly rejected by the judge. The Claimants then fell back on a secondary argument that the DePuy prosthesis had a materially greater risk of early failure and revision than its comparators, rendering it defective. Importantly the Consumer Protection Act provides that the claimants would not need to establish fault on the part of DePuy – a producer may be held liable for a defect that it took all possible precautions to prevent, subject only to the development risk defence.
If the claimants were able to establish a defect, they would still need to show causation. But as it turned out, it was not necessary to determine this issue in detail.
DePuy: not defective
In the course of a four month trial, the court heard from numerous experts in wide-ranging disciplines, considered two significant bodies of independent research data and analysed the medical guidance concerning MoM implants.
Importantly for product liability cases going forwards, detailed consideration was given to what circumstances the court should take into account when determining the requisite standard of safety. Following the reasoning of Hickinbottom J in the 2016 Wilkes case, Mrs Justice Andrews DBE confirmed that there is no rigid categorisation that must be followed. Rather, a judge is entitled to have regard to all circumstances, bearing in mind the need to be “vigilant not to let notions of negligence or other irrelevant considerations creep into that assessment”.
In undertaking that exercise, and particularly analysing the statistical evidence relied upon by the claimants, Mrs Justice Andrews DBE reached the following conclusions:
- It was known in 2002 that all prostheses produce wear debris and that this could cause adverse immunological reactions. DePuy had expressly warned of this risk occurring.
- A CE mark was granted for all the components in the DePuy implant despite the unquantifiable risk of an adverse reaction.
- A surgeon’s failure to discuss the risks with a patient could not have an adverse impact on the assessment of the objective safety of the product.
- There was no justification for setting the bar higher than the actual expectations informing the regulators, orthopaedic community, designers and manufacturers in 2002, even if it later became apparent that everyone was mistaken.
- There were far too many confounding factors affecting the reliability of the cumulative risks of revision for the DePuy implant to reach a conclusion based on the comparator evidence that the revision rates were materially worse.
The judge was unable to conclude on the balance of probabilities that there was a materially greater risk of the DePuy implant failing within the first 10 years than the comparator. So the claims against DePuy failed and there was no need for a detailed analysis of either the development risk defence or causation.
DePuy: the end of the story - good news for manufacturers and insurers
Unless the 312 claimants bring an appeal the case is over for them and likely many others in satellite litigation. For manufacturers and their insurers, this is a very positive outcome to an issue has been a concern for the device industry as a whole.
A note of caution - the decision concerned a claim against the manufacturer for product liability. It remains open for individual surgeons to be exposed to claims from patients that they were not fully informed of the potential risks involved with a MoM implant.
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