At the British Hip Society annual meeting 2012 in Manchester which finished last week, the latest research on metal bearing hips has been discussed. Data from the National Joint Registry and several clinical studies from around the United Kingdom has been carefully reviewed .
At the last annual meeting in Torquay in 2011, it was stated that the use large diameter metal on metal bearings in primary total hip replacement should be carefully considered and probably avoided (see below). This year, having evaluated the latest research, the British Hip Society Annual General Meeting unanimously agreed the following statements on March 1st 2012:
- The BHS 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.
- This advice does not apply to hip resurfacing
- The British Hip Society endorses the guidance issued by the MHRA on the 28th February 2012. Patients who already have metal on metal bearing implants should be followed up.
- The British Hip Society will continue to monitor the latest research in this field and will provide further guidance once more information becomes available.
This topic was considered in some detail. Several units including Belfast, Southampton, Cardiff and Stockton on Tees presented well researched and audited results of these devices at short to mid-term. There was a predominance of the ASR XL device, which has been withdrawn, but large diameter MOM devices from other manufacturers may also be showing similar results.
The presented results show a higher than anticipated early failure rate. These range from 21% revision rate at 4 years (potentially rising to 35% if all currently known painful implants progress to revision) to 49% at 6 years for the ASR XL device. Other devices have a revision or impending revision rate of 12 – 15 % at 5 years.