Toxic metal hip implants 'could affect thousands more people than PIP breast scandal'
UK regulators knew of risks but did not warn doctors and patients, alleges BMJ investigation
MHRA announces most patients with metal-on-metal hips should have regular MRI scans
By Claire Bates
Last updated at 3:38 PM on 28th February 2012
Tens of thousands of UK patients may have been exposed to dangerously high levels of toxic metals from failing hip implants, according to an investigation published in the British Medical Journal.
This is despite the risks being known for decades.
Hip implants, like breast implants did not have to pass any clinical trials before they were put into patients.
However, the report reveals that cobalt and chromium ions can seep into the tissues of patients with 'metal on metal' hip implants, causing local reactions that destroy muscle and bone, and leaving some patients with long term disability.
Studies have also shown that metal ions can leach into the bloodstream, spreading to the lymph nodes, spleen, liver and kidneys, before leaving the body as urine. There are also concerns about damage to chromosomes, leading to genetic changes.
Local tissue reactions associated with metal ions were first described in detail as long ago as 1975. However, according to the investigation the manufacturers remained silent in the face of mounting evidence of risk.
'This is one very large uncontrolled experiment exposing millions of patients to an unknown risk. We will only find out about the safety of these devices after large numbers of people have already been exposed,' says Michael Carome, Deputy Director of Public Citizen's Health Research Group.
The study by the BMJ in partnership with the BBC, also revealed that some companies changed the design of the metal hips - making the head of the joint larger - without performing safety trials first.
Experts say it is likely that these changes are responsible for the release of high levels of toxic metals into the body.
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The BMJ said despite concerns being raised, UK and U.S regulators failed to warn doctors and patients of the potential dangers.
They said evidence was mounting about high metal concentrations in patients with articular surface replacement (ASR) hips as early as 2006. But it was another four years until the UK regulator, the MHRA, issued an official safety alert and the ASR hip was recalled from the market.
Instead, it said the MHRA appointed a committee that included company representatives and several consultants to decide the fate of metal on metal hips.
As a result, the regulator concluded patients should be told about the risks, but no alert was issued to surgeons or patients.
During this time, implant rates peaked. In England and Wales over 20,000 large diameter metal on metal hips were implanted thereafter, while in the US, metal on metal hips are still being marketed to orthopaedic surgeons.
Just two hours before the BMJ report was released today, the MHRA published new guidance for British patients with all metal artificial hips.
The regulator said most patients should be followed up throughout their lifetime with regular magnetic resonance imaging (MRI) scans to check for any potential problems.
The regulator said around 49,000 patients out of 65,000 with all-metal hips were in a high risk category but insisted the scans were a 'precautionary measure.'
Dr Susanne Ludgate, Clinical Director of the MHRA, said: 'Most patients with metal-on-metal hip replacements have well functioning hips and are at a low risk of developing any serious problems.
However, Nick Freemantle, Professor of Clinical Epidemiology and Biostatistics at University College London says: 'We shouldn’t be in this position where we don’t know and there’s so much uncertainty. The stability of a compound should have been ascertained before it was used widely in people. As yet, we don’t know the consequences of this.'
Dr Fiona Godlee, BMJ Editor in Chief says: 'Hip replacements are one of the great successes of modern medicine. But a combination of inadequate regulation and untrammelled commercialism has caused actual and potential harm for large numbers of patients around the world.
'They should have known about the risks, as the manufacturers and regulators did, but they were not told.
'No pre-market system can ensure all devices are safe, but they can certainly make it more likely,' add Dr Carl Heneghan and colleagues in an accompanying article.
'Creating an independent system for post-marketing analysis for implantable medical devices that is robust and increasing international coordination around device alerts and withdrawals should go some way to sorting out the current mess.'
Full details of the investigation will be broadcast on BBC Newsnight tonight
What is a metal on metal implant?
Traditional hip replacements – carried out since the 1950s – used a metal ball and a plastic socket. In the 1990s, however, metal on metal types became popular.
In these products both the femoral ball, which sits on top of the leg, and the acetabular socket it fits into which is attached to the hip, are made of metal.
It was thought these could cope with more wear and tear.
Around 40,000 have them and they are still being fitted.
What is the concern?
In 2010, regulators became worried about the number of patients needing their operations redone because their muscle tissue had been damaged by the metal on metal hips.
It turned out tiny metal particles were getting into the blood, poisoning it and leaving patients in pain and with lasting damage to tissue. If the problem is not identified early enough, further operations can be more difficult.
Are all MoM hips dangerous?
The Medicines and Healthcare products Regulatory Agency ordered two types of hip implant manufactured by DePuy to be taken off the market.
Surgeons say their failure rate could be 50 per cent after just six years for full hip replacements, far higher than previously thought. Other metal on metal implants – of which the most popular is the DePuy Pinnacle – may also have higher than average failure rates, but there is not enough evidence yet to be sure.
What should I do if I have one?
If you have a DePuy ASR or ASR XL implant or do not know whether you do, you are advised to see your doctor and ask for a blood test to check the metal level, even if you are not experiencing any pain.
If you have another brand of metal on metal implant you are advised not to panic, but to have an annual check-up for five years. There is a website for ASR patients at asrrecall.depuy.com. DePuy has a helpline on 0800 2794865.
What is happening now?
The MHRA has issued a new alert for everyone with a metal on metal implant because surgeons fear the devices are more dangerous than had been appreciated. It says most patients should have regular MRI scans to monitor the hip. It can be viewed at mhra.gov.uk
Read more: http://www.dailymail.co.uk/health/article-2107640/Toxic-metal-hip-implants-affect-thousands-people-PIP-breast-scandal.html#ixzz1niouRGwW
Michael K Irwin