Hip replacement method 'unacceptable' for women

Surgeons should stop carrying out a common type of hip replacement operation on women because of "unacceptably high" failure rates, doctors claim today.

Total hip replacement with acetabular fracture fixation Photo: ALAMY

They have found the method, called hip resurfacing, leads to up one in nine operations in women failing within seven years, frequently because the joint becomes too painful.

Failure rates are up to six times higher than with more traditional techniques, they warn in The Lancet.

With hip resurfacing, the 'socket' part is completely replaced, just as it is in a total hip replacement. But rather than the 'ball' - the top section of the femur - being removed and replaced, it is retained.

Instead, the surgeon grinds down the uneven outer surface, and replaces that with a metal cap. The end result is a type of 'metal-on-metal' hip replacement.

The technique has been around since the late 1980s. Manufacturers of the implants have claimed they give patients better movement, and more years before the top of the femur needs to be removed. In particular, they have been marketed at under 55s.

More than 4,000 people undergo hip resurfacing in England and Wales every year, according to the National Joint Registry, and they account for about one in every 13 hip replacements.

But analysis of the registry by doctors in Bristol, Exeter and Derby shows startlingly high failure rates among women.

Ashley Blom, professor of orthopaedic surgery at Bristol University, said: "Resurfacing failure rates in women were unacceptably high. In view of these findings, we recommend that resurfacing procedures are not undertaken in women."

For a woman operated on at 55, the chance of her needing a 'revision' operation in seven years ranges from 8.5 to 11.7 per cent, depending on the size of the head of her femur. The smaller this bone, the greater the chance of failure.

These rates are much higher than using the 'traditional' option of a replacement metal ball and a plastic socket. With these, only about two per cent fail in seven years.

The failure rate of ceramic-on-ceramic joints - often recommended for younger patients - is just over three per cent.

Although the doctors want to stop hip resurfacing in women in the future, Prof Blom said those who had already undergone the operation should not be unduly worried.

He said: "If you're a 55-year-old woman with a small hip size, there's still nearly a 90 per cent chance that your hip resurfacing operation will not need revising in seven years.

"Hip replacements are fantastic things. What we are trying to do here is work out what's the best of a pretty good bunch.

"But if you do have a hip resurfacing, you do need to be monitored about once a year, especially if you are in pain."

In men, hip surfacing failure rates do not seem to differ much from other techniques.

The study is the latest to uncover problems with certain types of hip replacement. In 2010 one type of metal-on-metal implant, made by DePuy, was recalled due to very high failure rates. Earlier this year the Medicines and Healthcare Products Regulatory Agency (MHRA) warned tiny particles from metal-on-metal implants could leak into the blood, potentially causing neurological problems.

Professor Tim Briggs, a consultant orthopaedic surgeon, and until recently medical director of the Royal National Orthopaedic Hospital, welcomed today's research, saying it added to evidence there was a problem with hip resurfacing.

However, he said there could still be instances where it was the best option for a woman.

"It should be taken on a patient-by-patient basis, with decisions based on informed consent after full discussion," he said.

A spokesman for Birmingham Hip, a major manufacturer of hip resurfacing implants, said the conclusions "reinforce our existing analysis of the BHR Hip - that patient selection is very important".

Being a female patient was already a known "risk factor" that led to higher failure rates, he said.

But he added: "The BHR Hip gives younger patients the opportunity to enjoy pain-free living earlier in life and restores a higher level of physical activity than a total hip replacement, whilst keeping future treatment options open."