Metal on metal implants disintergrating
Medical regulators are considering new evidence about ‘metal on metal’ implants disintegrating, destroying muscle tissue and leaking metal into the bloodstream.
It comes as surgeons say that implants which have now been recalled have a failure rate of nearly 50 per cent after six years.
Some patients, however, may be unaware of the dangers.
Hip replacements, and less drastic hip resurfacing, usually offer a patient a 95 per cent chance of pain-free mobility for ten to 15 years.
But problems can occur with all-metal implants – used on 40,000 patients – when friction between the components causes tiny metal fragments to break off.
In 2010, two hip implants made by company DePuy were withdrawn from the market after concerns about their safety.
These accounted for around 10,000 of the metal on metal hips fitted in the UK since 2003.
Lawyers representing hundreds of patients who were given the DePuy ASR – used in hip resurfacing – and ASR XL – used in a full replacement – are preparing compensation claims which could run into six figures.
All patients with these products are advised to see a doctor to check levels of cobalt and chromium in their blood and whether they have any muscle damage.
It is unclear if all patients are aware of the risks. The British Orthopaedic Association suggested in a letter to surgeons that only 41 per cent had applied to be reimbursed for their treatment by DePuy.
Doctors say metal fragments could be toxic to the kidneys, and can also inflame tissue around the bone, destroying muscle.
Surgeons in the North East have compiled figures for 500 patients with DePuy implants showing a failure rate of up to 35 per cent after four years and 49 per cent after six years for full hip replacements.
Tony Nargol, an orthopaedic surgeon at North Tees and Hartlepool NHS Trust, said: ‘If some patients haven’t been told, that is appalling. We have been saying to the world that these implants are wearing out and there could be problems ahead, but we need to ensure the public gets the message.’
He said doctors should give all patients with an ASR – which stands for articular surface replacement – a blood test, take a sample from the liquid around their joint and have an ultrasound to check for damage.
Surgeons from Belfast and Cardiff also noted high failure rates for DePuy. The failure rate from other metal on metal devices can be as high as 15 per cent and patients are advised to have annual check-ups for five years.
IT consultant Penny Brown, 51, had a DePuy ASR resurfacing implant after years of gymnastics and skiing left her with a painful right hip. She was so pleased with the results, she agreed to help promote DePuy’s services.
Eight years later, however, she is taking legal action after her implant wore out and left the surrounding tissue full of debris.
It has since been removed. She said: ‘I cannot sit or stand for long periods and I’m a shadow of my former self. I’m no longer the hard working, vivacious woman I used to be and would still be if I had not had this implant.’
Metal on metal replacements became popular in the 1990s as they were thought to be more resilient than metal and plastic.
Bozena Michalowska of law firm Leigh Day, which is representing more than 300 victims, said patients may be entitled to compensation.
The Medicines and Healthcare products Regulatory Agency yesterday said it was consulting clinical experts on drawing up new guidance.
A spokesman said it had taken ‘prompt action’ over safety fears but added that most people with metal on metal replacements were at ‘low risk of developing serious problems’.
A spokesman for DePuy, a subsidiary of Johnson & Johnson, said the firm was working to support patients and reimbuse victims and doctors.
He said figures from the National Joint Register showed a failure rate of 17 per cent for ASR replacements after five years.