Metal hip replacements may lead to cancer
London: Surgeons have cautioned that the controversial large metal-on-metal hip replacement joints should no longer be implanted in patients, following evidence of links with cancer, poisoning and pain.
The British Hip Society, which represents surgeons carrying out replacements, is so concerned about the failure rate of the metal joints that it has said no more should be used, the Telegraph reported.
There are currently 49,000 people in Britain with the large metal-on-metal hip joints.
The warning comes days after the health devices regulator said all patients with the large diameter joints should have annual blood tests and possibly MRI scans for the lifespan of the joint.
The tighter regulations have been brought in after research showed the large joints rub together causing miniscule particles of metal to leach out into the surrounding tissue and bloodstream.
Experts in Bristol have reportedly found abnormal cells in the blood of patients with the hips that could trigger cancers.
The Medicines and Healthcare products Regulatory Agency said last week that blood tests should be carried out annually to check levels of cobalt and chromium in the blood and if levels are rising, a scan should be conducted to check for damage around the joint with a view to replacing it.
Patients with joints measuring less than 36mm and those who have had only hip resurfacing are not affected.
A statement agreed by the British Hip Society at its meeting in Manchester last week said: “The British Hip Society advises that stemmed, large diameter metal-on-metal primary total hip replacements using bearings of 36 mm or above should no longer be performed until more evidence is available, except in properly conducted and ethically approved research studies.”
Patients have suffered pain and swelling of the joints and when scanned it has been found tissue surrounding the joint has been damaged, fluid may have collected and solid lumps have been detected.
Prof Joe Dias, President of the British Orthopaedic Association told the Daily Telegraph that around 5.5 per cent of the large metal on metal implants needed to be replaced because of wear and tear within five years compared to around two per cent of the standard metal on plastic ones.
“It is clear that as a class these large metal on metal implants, which were introduced to make the implant last longer in younger patients, are not fulfilling that aspiration. Because they are not fulfilling that aspiration, in that at the moment they are worse than metal on plastic, it does not make sense that surgeons continue to use them,” he said.
He said the advice from the British Orthopaedic Association and the British Hip Society is not driven by the concerns over metal ions in the blood causing cancer but by the failure rate.
“We use the best implant for the patient in front of you. We were trying to make the implant last longer but whenever you try to improve something sometimes you will succeed and sometimes you won’t,” Prof Dias explained.
“It is not clear that there is no advantage of using the large head metal on metal implants.
“We do want to reassure patients who have got a metal on metal implant you are not more likely to develop cancer - there is absolutely no evidence of that at this stage,” he stated.
Prof Dias added that the concern over the level of metal ions in the blood was currently related to soft tissue damage around the joint, which causes swelling and pain and makes any further surgery more complicated.