By Consultant Orthopaedic Surgeon and Hip Specialist, Mr Warwick Radford
Metal on Metal Hip Replacements – should I be concerned?
Recent television programmes and press articles have highlighted surgeons’ concerns regarding metal on metal hip replacements to the point where some say they should no longer be used. Several manufacturers have already withdrawn this type of implant. The metal on metal debate is complex and can be confusing to the lay person as all hip replacements contain at least one metal component – which is why they frequently set off the alarms at airports. However, in relation to metal on metal (MOM) implants, both articulating surfaces have to be made of metal and the majority of hips implanted in the UK are not of this type (usually they have a metal on plastic bearing, or else ceramic on plastic or ceramic on ceramic).
The problem with MOM hips is that metal ions (Cobalt and Chromium) are released from the surfaces due to wear that occurs in everyday use. The amount of ions released can be measured in the blood and for many people these amounts are within acceptable limits. Unfortunately, in some people there are complications with the hip replacement when the tissues around the hip react badly to these ions, leading to inflammation which can damage adjacent muscles and bone. This process is not always apparent and can occur unnoticed by the patient. It is for this reason that the MHRA (Medicines and Healthcare products Regulatory Agency) recently recommended that patients with MOM hips be followed up on a regular basis. Ideally this follow-up should be by an Orthopaedic Surgeon with experience of MOM bearings who should examine your hip, take an x-ray and measure your metal ion levels with a blood test. Most patients with MOM hips will not have any problem but the results may suggest further tests are needed – usually an MRI scan or CT scan or both.
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By way of reassurance, the majority of MOM hip replacements are functioning well and should continue to do so, but it is wise for anyone who has, or thinks they may have, a MOM hip replacement to seek advice and an appropriate referral via their GP if necessary.
Can metal on metal hip replacements cause cancer?
Recently there has been some concern that MOM hips may be linked to bladder cancer, although the evidence has not been peer-reviewed or proven. To put Cobalt-Chromium MOM bearings into context, these were first used 50 years ago. It was because some lasted for more than 30 years that these metals were chosen for MOM hip replacements. Over the years researchers have looked into whether any type of hip replacement can cause cancer but to date no direct link has been found.
I think I might have a MOM hip replacement – what should I do?
Contact your surgeon or the hospital where this was carried out to find out (many of my patients have already done so).
I had a resurfacing hip replacement – is that OK?
All resurfacing hip replacements use a metal on metal bearing – you should have a check-up with an Orthopaedic Surgeon.
I know I have a MOM hip and it’s absolutely fine – am I OK?
Probably – but you need to be sure so see your GP to be referred to an Orthopaedic Surgeon for a follow-up.
