How safe are metal-on-metal hip implants?

A British Medical Journal and BBC Newsnight investigation has revealed that hundreds of thousands of patients may have been implanted with poorly regulated and potentially dangerous hip devices. The implants concerned are metal-on-metal, where the head and the lining of the cup it fits into are made of cobalt-chromium alloy rather than ceramic or polyethylene.

Since arriving in 1997, they have been hailed as a leap forward for orthopaedic medicine. In reality, they have been responsible for an average failure rate after seven years of 11.8% for resurfacing and 13.6% for metal-on-metal total hip replacement. This compares with rates of 3.3% – 4.9% for hip implants made from other materials.

The failure rates for women who underwent this treatment have been reported as being up to five times higher than failure rates found in male patients.  Professor Ashley Blom, who led the team of researchers from Bristol University, has suggested that resurfacing implants should never have been used in women and should not have been recommended to the majority of men either.

In 2010, the UK regulator, the Medicines and Healthcare products Regulatory Agency (MHRA) issued a product recall for DePuy ASR, a brand of metal-on-metal hip replacements. The concern is that as the hip replacement wears down, metal particles can be released which react with the surrounding soft tissue and enter the joint and bloodstream and can cause extensive damage to muscle and bone. This is known as genotoxicity and can lead to long-term disability as well as severe pain.

The MHRA’s advice remains that those patients with a metal-on-metal hip implant should be closely monitored for five years and probably for the life of the implant. Those patients who have had a hip replacement withdrawn and are experiencing pain should have the cause of that pain thoroughly investigated immediately.

Multiple studies and research organisations have expressed concern about the level of toxicity and the cancer causing potential of metal-on-metal hips. Some studies have shown that the use of these hip replacements have resulted in 20% of patients having 600 times the normal level of cobalt in their bodies, and the risk of developing lymphoma, leukaemia and malignant tumours have increased accordingly. The British Medical Journal and BBC Newsnight have both reported that De Puy may have been aware of the possibility of carcinogenic potential of their implants in 2005, but failed to reflect their concern whilst continuing to advertise and supply their hip implants to the general public.

If you have had a metal-on-metal hip replacement or resurfacing treatment and are concerned about the potential failure rate or the increased likelihood of contracting a serious illness, please contact Jane Rogers or Gillian Tayler on 0117 929 0451 who will be happy to assist in the matter.


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