Experts published evidence suggesting people given the best-selling Pinnacle hip implant may need surgery to have them removed. File image
Hip implants given to 12,000 people in Britain are ‘unacceptably’ prone to failure, doctors have warned.
Experts have published evidence which suggests people given the best-selling Pinnacle hip implant are at high risk of needing surgery to have them removed.
The metal-on-metal hip implant, made by Johnson & Johnson’s prosthetics company DePuy, is the most-used in the world.
But it is already subject to a multi-million pound US lawsuit, and now further concerns have emerged in the UK.
Surgeons in Britain say they have operated on patients with ‘black tissue’ caused by chemicals leaching out of the metal joint.
They say the implants are too often made slightly too big or too small, with the resulting friction causing chromium and cobalt to rub off into the blood stream.
DePuy was forced to recall a different implant - the ASR - in 2010 after the devices were linked to muscle and bone damage.
In March this year, Johnson & Johnson was ordered by a Texas federal jury to pay $500 million (£340million) to five people who said they were injured by the Pinnacle joints.
Johnson & Johnson has said the company will appeal against that verdict but thousands more people have launched action.
According to the National Joint Registry, 11,871 people in England and Wales have received the Pinnacle implant.
Study leader Dr David Langton, whose work was published last night in the medical journal BMJ Open, said: ‘We have found that they fail at a higher rate than conventional ones but they fail in a much nastier way.
‘You get very high levels of chromium and cobalt around the hip and that can go into the bloodstream. There can be black metal-stained tissue.
‘What we’ve found is that some of our patients have come back with lots of pain. The implants have then been taken out by us.
‘In total myself, I’ve looked at between 150 and 200 Pinnacle implants.’
Dr Langton, from the University Hospital of North Tees, added: ‘We’ve reported this and had several meetings with DePuy and the MHRA.
‘We physically handed the implants to DePuy and showed them how they were not the right size and how they were going to fail. In my opinion, they should never have left the factory.
‘Hips should fail at no more 0.5 per cent per year but we found the Pinnacle has been failing at a significantly higher rate than that.’
The research team found that Pinnacle metal on metal implants manufactured and implanted since 2006 are more prone to failure.
They found a ‘revision rate’ - in which further surgery is needed - in 16.4 per cent of cases, which they said was ‘unacceptably high’.
The team looked specifically at the long-term performance of the 36mm Pinnacle hip.
Over the study period, 489 metal on metal Pinnacle hips were implanted into 434 patients.
The metal-on-metal hip implant - similar to the one pictured - made by Johnson & Johnson’s prosthetics company DePuy, is the most-used in the world
Of these, 352 patients attended future clinics and 71 metal hips required surgical removal and replacement.
The study found that before 2006, 12 per cent of implants failed to meet the manufacturer’s product specification, meaning they were slightly the wrong size or shape.
But after 2006 more than 36 per cent failed to comply.
And in over 40 per cent of cases, the taper surface - a key part of the implant - was defective.
The authors said this was significantly associated with the excessive release of metal particles.
A spokesman for the MHRA said last night: ‘MHRA take allegations of device non-conformities seriously and will investigate these with manufacturers when sufficient evidence is presented to MHRA.
‘The majority of patients who receive hip implants have well-functioning hips and are at a low risk of developing any serious problems.’
A spokesman for DePuy insisted that the company stood behind the ‘strong record of safety and effectiveness’ of its hip implants, and claimed there were ‘significant flaws’ with the way Dr Langton’s research was conducted.
She added: ‘There are no manufacturing problems … as the Langton paper suggests. The paper is also inconsistent with the results of many peer-reviewed studies that were conducted with more scientific rigor and transparency.’