Defective Knee Replacement Implants

Here at McCarthy + Co Solicitors LLP, our team has acted for many clients in knee replacement claims, from cases involving implant loosening and premature wear to those requiring corrective surgery. This work is led by our head litigation lawyer, John McCarthy, who has extensive experience in defective medical device claims, including for patients fitted with knee implants such as the DePuy Attune, and devices from manufacturers including Zimmer Biomet and Stryker. To arrange a time to speak with John, complete our quick and confidential online form.

How knee implants fail

Modern knee replacements are usually very successful and long-lasting. When an implant fails early, however, it can cause significant pain and disability and often requires revision surgery. Common modes of failure include:

• loosening of the implant from the bone, causing pain, instability, and reduced movement;
• wear of the implant materials over time, producing debris that inflames the surrounding tissue;
• misalignment of the components, leading to abnormal movement and faster wear;
• infection at the implant site;
• fracture of the bone around the implant; and
• complete failure of the implant, requiring revision surgery.

Where a failure of this kind results from a defect in the implant, rather than from its natural lifespan or the way it was fitted, there may be grounds for a product liability claim against the manufacturer.

How often do knee replacements fail?

It helps to see the failure of a defective implant against the backdrop of how knee replacements usually perform. Implant performance is tracked by national joint registries, and regulators expect a knee implant to have a low failure rate over its lifetime. Most knee replacements comfortably meet that standard, as the figures below show, which is why an early failure is worth investigating.

Sources: the NICE benchmark of 5% at 10 years, as cited in the National Joint Registry 21st Annual Report; the 3% figure from a 2020 registry review; the under-55 figure from National Joint Registry annual report data; and the partial-knee range from a 2020 multi-registry summary.

The most common reasons for a knee revision are infection, aseptic loosening, and instability. Well over a million primary knee replacements are recorded in the National Joint Registry, and a well-performing modern implant has around 96 to 97 per cent survivorship at ten years. Revision is markedly more likely in younger, more active patients, and partial knee replacements are revised more often than total knee replacements.

The DePuy Attune knee system

The DePuy Attune knee system, introduced in 2013, is one we are frequently asked about. From around 2017, a number of published case series and retrieval studies reported early loosening of the tibial baseplate, the metal tray fixed to the shin bone, through debonding at the interface between the implant and the cement. In response, DePuy introduced a redesigned tibial baseplate, the Attune S+, in 2017, intended to improve cement fixation.

It is important to be balanced about what this means. The Attune has not been recalled over the tibial loosening issue, and national registry data has not shown it to be a clear outlier, with reported revision rates broadly in line with, or better than, comparable implants. At the same time, individual patients have experienced early tibial loosening and needed revision surgery. Whether a particular case involves a defective product is therefore a fact-specific question, which turns on your medical records, the retrieved implant, and independent engineering and medical evidence. We can advise you honestly on how the law applies to your situation.