Metal-on-metal hip implants: where we are and what steps can you take

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This article reviews the brands, the injuries and the claims that have arisen from their use and offers guidance on how best to deal with the issues arising.

Over the past few years there has been an increasing focus upon the safety or otherwise of the surgical use of metal-on-metal (MoM) hip implants during hip replacement operations. This article intends to bring PI insurers and medical practitioners up to speed with: 1) the manufacturers/ brands of implants which are currently being investigated; 2) the alleged injuries caused by the use of metal-on-metal; 3) the status of the claims (largely in their infancy) that are already being pursued in the UK along with examples from the international arena where the claims are more advanced, and 4) advise certain action points.

Background and the alleged injuries caused by the use of MoM implants

From their arrival on the orthopaedic scene in 1997, MoM hip implants were marketed as the latest advance in hip replacement and were targeted at young active patients who needed a hip replacement that would last a whole lifetime. MoM devices have been implanted into over 60,000 patients in England and Wales since 2003 when the National Joint Registry first began to record procedures.

While cobalt-chromium implants have been used successfully in orthopaedics for years - for example, in knee operations and fracture repair - some MoM prostheses are thought to release ions on a much greater scale than previously thought. A failing MoM prosthesis is associated with circulating cobalt and chromium concentrations that may be several times higher than those seen in patients with well-functioning prostheses. It is alleged that these ions can seep into local tissue, causing reactions that destroy muscle and bone and leaving some patients with long-term disability. Case reports also suggest that very high blood metal concentrations are associated with systemic effects including cardiac, neurological, and endocrine dysfunction (see Metal Exposure after Hip Replacement and the Risks of Systemic Toxicity Journal of Trauma and Orthopaedics: Volume 03, Issue 02, pages 42-43 by J. Mark Wilkinson).

Following various investigations, the MHRA’s Committee on Safety of Devices concluded in July 2007 that patients should sign a consent form “which sets out the fact that the risks associated with metal wear debris have been discussed, including the genotoxic risk and possible sequelae.” The committee wanted to “ensure patients know there is a risk now and sign consent if necessary,” but, crucially for surgeons, clinics and their insurers, this requirement was not communicated widely - no alert was put out to surgeons or patients.

Only in March 2011 did the British Orthopaedic Association warn that large diameter MoM total hip replacements should be “carefully considered and possibly avoided.” In February 2012 the UK Medicines and Healthcare products Regulatory Agency (MHRA) published a medical device alert, updating it in June 2012 with advice on the management and monitoring of patients with MoM hip systems.

Litigation

DePuy ASR MoM systems is still the most widely publicised MoM litigation. In the USA, a settlement scheme was established after two test trials in 2013: qualifying claimants will receive a Part A “base award” of US$250,000. Factors which may result in reductions to the base award include: how long the MoM was implanted; whether the claimant smoked at the time of their surgery; whether the claimant had a previous hip implant; the claimant’s age at the time of the implant; and whether their BMI was greater than 35. This gives an indication of the types of awards and considerations that the court here may take into account.

A Part B “Supplemental Award” may also be paid to claimants who can demonstrate that they have experienced “extraordinary” events as a result of their MoM. Examples include bilateral hip surgery, multiple re-revisions and medical events associated with the revision surgery (such as a heart attack, stroke, deep vein thrombosis). The deadline to enrol in the American litigation passed on 1 May 2015.

In this jurisdiction, English claims are currently being brought under various Group Litigation Orders (GLOs) which are just starting to be actively managed by the Court.

Interestingly some claims have also been brought in England by foreign claimants as a result of the manufacturer defendants being domiciled in England. In Allen v Depuy International Ltd, a group of six sample South African claims and four sample New Zealand claims were brought. It was determined that the applicable law was the law of the place of injury (South Africa and New Zealand) and not the place of manufacture (England) as the claimants had argued. The South African law claims were then stayed, whilst the New Zealand law claims progressed to a further preliminary issue trial in March 2015 before Simler J to determine the effect of the applicability of New Zealand law.

It was held that the New Zealand claimants were precluded by the operation of the statutory bar in section 317(1) of the Accident Compensation Act 2001 (New Zealand) from bringing claims for damages for personal injuries in England.

Particularly relevant for insurers, the effect of the statutory bar was to remove heads of loss for negligently inflicted or other personal injury where cover was available under a comprehensive no-fault compensation scheme.

For clarity, the defendants to the majority of the claims and the GLOs are the manufacturers. This is not the case where there are allegations of “mix matching” implant components however, where breach of statute, contract and negligence are pleaded in individual cases and where individual practitioners and clinics are being accused of various misdemeanours including:

  • Mismatching where there was “uncertainty as to the wear of such components whereby there has been no specific testing”
  • Mismatching which was neither authorised nor condoned by the manufacturers
  • Producing or manufacturing the implants under sections 2(1) and 2(2) of the Consumer Protection Act (and therefore falling foul of strict liability provisions)
  • Breach of the Sale of Goods Act and the Supply of Goods and Services Act

In such cases, insurers need to be alive to the fact that their PI policy wording may well ‘bite’ and clinics and medical practitioners must swiftly appreciate that these are potential negligence cases which need to be notified as a matter of urgency and may not automatically fall to the manufacturers to cover.

Existing GLOs

DePuy International Ltd is resisting claims in respect of its large-headed MoM Pinnacle hip, and a GLO was made in respect of that group action on 31 July 2014, the defining issues being whether there was a defect in the defendant’s product and whether the damage was caused wholly or partly by a defect in the defendant’s product. The Register is still open and there is no closing date as yet. Lawyers representing over 1000 individual people who claim they were implanted with failed implants as well as those representing Depuy Synthes, Zimmer, Corin, Smith & Nephew and others attended a CMC at the High Court in London on 12 November 2015. The purpose of the CMC was to ascertain how to manage the claims through to Trial. 11 different prosthetic hip devices were the subject of that CMC including; the Pinnacle Ultamet total hip device (Depuy); the Zimmer/Metasul total and resurfacing devices (Zimmer); and, the Birmingham Hip Resurfacing device (Smith & Nephew).

A GLO under the Consumer Protection Act was also made in respect of Zimmer Durom Resurfacing hip systems in December 2014. The judge ordered that the Group Register be closed on 30 October 2015, after which no new individuals will be able to join the Group Action litigation. In both GLOs, Hickinbottom J has been appointed as the managing judge.

To provide some detail on some of the other manufacturers subject to claims:

Smith & Nephew - certain groups of patients implanted with the Birmingham Hip Resurfacing (BHR) system are allegedly at a higher risk of revision compared to other groups. Specifically, those patients who are at highest risk of harm and premature revision surgery when implanted with a BHR replacement are (it is argued): females; males aged 65 and over; and those who receive a femoral component size smaller than 48mm. Smith & Nephew have amended their instructions for use to ensure that these high risk patients are not implanted with a BHR device.

Finsbury Orthopaedics - Now owned by DePuy International (part of Johnson & Johnson), Finsbury Orthopaedics have recalled their ADEPT 12/14 modular head that was used on metal-on-metal implants in January 2013 due to findings of excessive metal wear debris. In January 2014 they then recalled their ADEPT resurfacing implant for all components smaller than a 48mm femoral head.

Wright Medical - The Wright Medical Conserve Plus has a seven year revision rate of 10.63 per cent, which is well above the NICE recommendations of less than a 5 per cent revision rate at 10 years.

The Corin Cormet hip system and Biomet devices M2a-38 and M2a-Magnum are both affected by excessive metal wear debris.

Action points

For surgeons and clinics
Reiterating the obvious, MoM implants should not be used. Asymptomatic patients with MoM hip implants have been advised to continue to follow-up with their orthopedic surgeon every one to two years to check for early signs of change. Thus, where patients report symptoms which could be attributed to their MoM implant, surgeons should consider several tests to evaluate the cause of the symptoms, including:

  • Joint aspiration
  • Soft tissue imaging
  • Blood tests including checking levels of metal ions in the blood

Medical practitioners (most likely to be surgeons) and clinics are advised to notify their insurer promptly if they become aware that they may be subject to a MoM implant claim – most likely to be of the "mixing and matching" variety. Along with the notification, provide copies of the employment contract and the dispatch notes for the products as this will assist lawyers in determining who was the ultimate legally defined ‘supplier’ of the components.

Additionally the following documents should be sought out and provided to insurers and/or lawyers once lawyers are involved:

  • Any clinic protocols on the use of hip implants and mixing and matching components
  • Relevant manufacturer information booklets
  • Information where possible from the National Joint Registry as to the number of operations conducted using these combinations
  • All relevant clinical notes

For insurers

Insurers are reminded that where a claim is brought, it may not be a pure product liability case. There may be arguments that individual practitioners have been negligent and therefore the claim may not be outside the usual PI policy remit. Also work closely with your insureds and lawyers to determine the correct contractual position as this could be very significant especially in a ‘mix and matching’ case. PI underwriters would be wise to exclude MoM cover from policies going forward and to carefully review all their policy wording relating to the use of medical implants of any kind.

For those insuring the manufacturers listed above and where the product liability policies bite, be alive to the fact that other GLOs may follow suit once it is clear how the current ones are progressing. Additionally, keep an eye on the closing date of the registers for the current GLOs as soon there may be arguments against latecomers to the litigation.

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