Knee implant used by NHS known for years to be faulty

A knee-replacement implant, used in thousands of UK operations, was known to have a concerning failure rate eight years before it was finally withdrawn, the BBC has discovered.

Patients have told File on 4 Investigates how they were left immobile or addicted to painkillers after receiving the NexGen knee implant, because it ended up slipping out of place. Hundreds of people have now had to undergo a second corrective operation.

Knee surgeons say the implant's US manufacturer, Zimmer Biomet, took too long to acknowledge there was a problem with one particular component.

Zimmer Biomet says patient safety is its "top priority" and that its products are approved in accordance with the relevant regulations.

Debbie Booker from Southampton had an operation to replace her left knee in 2016.

Although initially it appeared to have been successful, she started to experience severe pain a year later while on holiday in Majorca.

"I laid a bag of ice on my knee and for four days I had to do that every few hours because I was in agony," she says.

Debbie says the pain resulted from the knee implant slipping from the tibia and wearing away the bone.

Over the next few months she says she became reliant on prescription painkillers: "I was on fentanyl and morphine. It took me a long time to come off of the morphine because I was addicted."

Zimmer Biomet started marketing this modified version in 2012. It was cheaper than the earlier model, so it made financial sense for the NHS, according to Prof David Barrett, a knee specialist at Southampton University.

"[The NHS] were justified by saying, 'we have every reason to think it'll be fine,'" he says.

In the decade that followed, more than 10,000 patients were fitted with this version of the implant.

However, File on 4 Investigates has discovered that concerns were first flagged in 2014 by the National Joint Registry (NJR) which keeps a record of implant surgery across England, Wales and Northern Ireland.

At that point, there was insufficient data to draw any reliable conclusions, the NJR told us. It is not an easy task to isolate a specific component that is not working as it should, it added.

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Source: BBC News, 12 August 2025