Metal-on-metal hip replacements 'high failure rate'

17 Mar 2012, 02:16
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Metal-on-metal hip replacements 'high failure rate'

Metal-on-metal total hip replacements have a much higher failure rate than other options and "should not be implanted", say researchers. They said data from the world's largest register of hip implants provided "unequivocal evidence" of the failure rate.


The risk was greatest for women, the young and for large implants.


The UK health regulator has already advised annual checks for people with large head metal-on-metal implants.


Hip replacements are one of the great successes of modern medicine, restoring movement and cutting pain. Yet, all replacements have a risk of failure, such as the new joint coming loose, dislocating or through wear and tear. This study, published in The Lancet, showed some fail far more than others.


Patricia Clement suffered pain on a daily basis after having a metal-on-metal hip implant. Hip replacements come in different varieties such as all metal, all ceramic or metal-on-plastic.


Researchers at the University of Bristol analysed information from 402,051 hip replacements recorded in the National Joint Registry of England and Wales. It showed that, overall, 6.2% of metal-on-metal hips had failed within five years. At the same point only 1.7% of metal-on-plastic - and 2.3% of ceramic-on-ceramic - had failed.


The risks were greater in women. The report said: "Revision rates for stemmed metal-on-metal implants in women were up to four-times higher." Men were three-times more likely to need a replacement.


Larger implants were also linked to an increased risk of problems with metal-on-metal with "each 1mm increase in head size being associated with a 2% increase" in the risk of revision. Ceramic implants performed better as the head size increased.

Risks were also higher for younger patients.

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