On 1 December 2015 we wrote this article on metal-on-metal (MoM) hip implants and the current state of claims. Below we provide an update on the issue.
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). As such, they were thought to be more durable than existing models, and they were frequently presented as being more suitable for younger patients. They were also thought to present a lower risk of dislocation because they often had a larger head. About 56,000 patients had MoM implants over a number of years.
Unfortunately, MoM implants proved defective and have now been withdrawn from use. At the risk of over-simplification, there are essentially two problems with them. First, rather than being more durable than other models, their failure rate is significantly higher – in some instances more than six times higher than the average. As a consequence many patients have undergone revision surgery that would not have been necessary had a different model been used. Second, friction on the metal implants leads to particles breaking off and entering the patient’s body. This can lead to inflammation of soft tissue around the implant and discomfort.
The Medicines and Healthcare products Regulatory Agency (MHRA) has understandably taken an interest in MoM hip replacements. Advice was given in 2012 on the treatment of patients with these implants. At that stage the MHRA recommended that asymptomatic patients did not require further follow up unless they had implants with a particular sized head, or had DePuy products implanted.
On 29 June 2017 the MHRA issued revised guidelines advising that all MoM hip implant patients, whether suffering from symptoms or not, should undergo further treatment. Specifically, blood level testing and radiographs had to be undertaken, and in many cases MRI scans are required too.
The change has been occasioned by increasing concern about soft tissue damage to MoM patients. Specifically, orthopaedic experts have noted that soft tissue injury and even tissue necrosis can occur in MoM patients who display no outward symptoms of implant degeneration or failure. Early detection of such problems gives patients better prospects of success if a revision procedure is required. Therefore the MHRA requires further investigations to be undertaken of all patients. The evidence shows that the majority of MoM implant patients had a satisfactory outcome and will still not require further surgery. Given the higher than average failure rate, that is not something the MHRA is prepared to assume.
Some coverage of the MHRA’s announcement focused on the presence of ions in the bloodstream. This is used as a test to determine whether the implant is eroding – a word down implant releases metal fragments. Despite some commentary to the contrary, the presence of such ions is not an indication of sepsis or blood poisoning. The Department of Health has been keen to point out that only in a handful of cases has a high level of metal ions in the blood been linked to symptoms elsewhere in the body.
There is litigation afoot against a number of MoM implant manufacturers. In respect of three manufacturers there are Group Limitation Orders (GLOs) in place: these relate to DePuy Pinnacle implants, Zimmer implants and Corin implants. Claims against other manufacturers of MoM implants (specifically Biomet, Finsbury and Smith & Newbury) have been brought, but no GLOs have been ordered in respect of such.
At present a trial is proceeding in respect of the DePuy Pinnacle and the Corin implants. That trial started in mid-October 2017 and is expected to end in late January 2018. We understand that approximately 300 claimants involved, with Leigh Day & Co as the lead solicitors. It has been billed as the biggest product liability case to reach the courts in years.
Claims against other manufacturers are stayed whilst the DePuy and Corin claims are resolved. The decision in the DePuy/Corin litigation will not bind the other manufacturers, but it will be highly influential and may lead to those matters being compromised.
Outside the main litigation there have been other actions involving MoM implants, including one reported decision. That decision was Wilkes v DePuy International Ltd and concerned a MoM implant where the C-Stem (a part of the implant) fractured. It was the trial of a preliminary issue, specifically whether DePuy was liable under the Consumer Protection Act 1987. That claim failed. The court found that the C-Stem met regulatory standards and had a very low failure rate (c0.004%). It was not, therefore, defective within the meaning of the Act. Given the high failure rates of the MoM implants in the GLO litigation, a court may reach a different conclusion in respect of those.
A number of settlements have been reported from 2015 and 2016 via Lawtel’s PI case reports. Most concern the positioning of the acetabular cup which allegedly resulted in the failure of the implant, in some cases relatively rapidly. The reported settlements are around £20,000 to £25,000, with one slightly higher where the claimant had ongoing symptoms as a result of an adverse reaction to metal debris. This might give an indication of the likely quantum in the GLO claims if liability is established, although much will depend on each patient’s circumstances.
Two points emerge from the review of the current position.
First, we are reasonably close to having a decision that will set out clearly where we stand on MoM implants. Assuming the DePuy/Corin action runs its course, that decision will arrive in the first half of 2018. Regardless of the outcome, it is likely to lead to a number of settlements as the other manufacturers use the decision to inform their approach to their claims.
Second, the MHRA’s decision to have all MoM patients investigated may lead to further claims in the short term. The medical research showed that patients could be suffering harm from their implants without that being evident at this stage. Discovery of such harm could lead to claims. On the other hand, such claims may have developed in the future in any event. Examining those patients now could mean that their claims are flushed out now, rather than materialising at some point in the future.