Experts call for metal hip replacements to be banned

In the latest in a long line of reports damming the use of metal-on-metal hip replacements, medical experts have this week urged surgeons to stop using metal-on-metal hip units, stating: “Metal-on-metal stemmed articulations give poor implant survival compared with other options and should not be implanted.”

The report, published in the Lancet medical journal, conducted research based on the National Joint Registry of England and Wales, one of the largest databases of joint replacement records in the world. The report’s findings support those of previous studies which have found the failure rates of metal-on-metal hip replacements to be significantly higher than traditional ceramic models.

These findings follow the Medicines and Healthcare Regulatory Agency’s (MHRAs) updated advice to surgeons released just two weeks ago. This latest guidance sets out requirements for almost 50,000 metal hip patients to be followed up and tested for problems annually, for the life-time of the hip implant.

The report found that across all models of metal-on-metal hip replacement metal implants failed sooner than other types, with a revision rate of 6.2% after just five years. This compares with 2.3% for ceramic-on-ceramic models and 1.7% for metal-on-plastic. Where the metal ball and socket of an all-metal hip rub against each other, metal particles of cobalt and chromium (used in the manufacturer of the units) are released into the bloodstream causing swelling, loss of mobility and persistent pain.

This latest report looked at over 31,000 metal-on-metal implants and found a direct correlation between failure rates and the type and size of the unit implanted; with larger units more susceptible to failure. A 1mm increase in the head size of the metal-on-metal unit led to a 2% increase in the risk of failure.

In addition to failure rates differing between type and size of the unit, rates also differed between the sexes with women facing a greater risk of their implant failing than comparable men.

The authors of the report said supported the MHRA advice, stating: “All patients with these bearings should be carefully monitored, particularly young women implanted with large diameter heads.”

However, they went on to say surgeons should look to use other models of hip implant in hip replacement operations, arguing: “We think there are better alternatives so we don’t see a reason to use stemmed metal-on-metal implants any longer.”