Further Information about Metal on Metal
Metal on polyethylene total hip replacements have been shown to be highly successful in the medium and long term. However with increasingly higher expectations of patients there is always the need to improve results, one of problem has been wear of the hip replacement joint and the need for revisions, particularly in younger patients. This led to innovations seeking to improve the survival of the total hip replacement in this category. The large head metal on metal stemmed implants were one of these innovations.
This recent analysis in the Lancet of the data from the National Joint Registry has demonstrated that in the medium term up to 7 years, more stemmed large head metal on metal implants need revision than metal on polyethylene total hip replacements. The analysis of this data demonstrates that the aspirations we had for this particular innovation have not been met.
However around 94% of patients with these implants have had significant pain relief and have not needed revision although a greater proportion fail, particularly if a large ball greater than or equal to 36 mm in diameter is used on a stemmed hip replacement, if the patient is young and if the patient is a female. Patients need to consult their surgeon if they are worried.
Hip surgeons at the recent British Hip Society meeting in Manchester, after considering the mounting evidence, had already issued a statement advising surgeons to stop using this this type of hip replacement. We agree that surgeons and hospitals must now not use such implants (large heads, stemmed, metal on metal bearings) which are not performing as well as was hoped.