ALL metal hip joints 'must be banned': Failure rate 'four times higher than other types'
07:46 GMT, 13 March 2012
Experts are demanding that metal-on-metal hip replacements are banned after finding ‘unequivocal’ evidence of their poor performance.
The biggest study of its kind revealed the implants, fitted on almost 50,000 patients, have a failure rate almost four times higher than other types.
Researchers at Bristol University looked at data from more than 400,000 hip replacements of different types carried out over the past eight years.
Findings: The biggest study of its kind revealed the implants, fitted on almost 50,000 patients, have a failure rate almost four times higher than other types
The failure rate for metal-on-metal implants was particularly high in women in their 50s and 60s, and in patients with larger metal ‘heads’, the part which fits into the socket.
Professor Ashley Blom, head of orthopaedic surgery at the university, said: ‘The results we found cannot be accounted for by one rogue brand.
‘The bigger your numbers, the more security you have in your findings and this study dwarfs all the previous ones put together, and shows a higher failure rate than other types of implant.
‘We do not believe metal-on-metal articulations should be implanted, and all patients with these bearings, particularly young women implanted with large diameter heads, should have checks every year at the very least.
‘That is how often you have your car serviced and it shouldn’t be any less for a machine inside your body.’
Announcement: Two weeks ago, regulators announced that patients with metal-on-metal implants should have a scan and a blood test every year for life
In metal-on-metal implants, both the ball and socket of the hip are replaced with metal as opposed to one or both being another material, such as plastic or ceramic.
It is deemed a failure if there are problems and it has to be taken out.
The latest research, published in The Lancet, not only examined the largest number of patients but removed results from discredited ASR implants.
These implants were made by DePuy, a subsidiary of Johnson & Johnson, and were given to around 10,000 patients. But they were withdrawn in 2010 after having a failure rate of up to 20 per cent.
Professor Blom and his colleagues used data for England and Wales from the National Joint Registry, including 31,000 patients with metal-on-metal replacements.
This showed that failure rates were 6.2 per cent over five years. Metal-on-plastic implants had a much lower failure rate of only 1.7 per cent in the same period. The figure for ceramic ones was 2.3 per cent.
For 55-year-old women with a large head implant of 46mm, failure rates were as high as 10 per cent. It was more than 8 per cent with a 36mm diameter head.
Surgeons began uncovering problems with the devices when patients reported pain and mobility problems.
Two weeks ago, regulators announced that patients with metal-on-metal implants should have a scan and a blood test every year for life.
The Medicines and Healthcare Regulatory Agency guidance was issued after it emerged that tiny metal ions could break off and get into the bloodstream, potentially causing muscle and bone damage.
But yesterday the agency insisted the number suffering complications was ‘small’ and did not justify a ban.
Around 65,000 patients have received metal-on-metal hip implants since 2003, of which 49,000 are affected by the MHRA’s guidance because the joint head is 36mm or greater.