Thousands of patients having hip or knee replacements on the NHS may find that their new joints do not last more than a few years.
A study of joint replacements in England has found that the latest surgical techniques of hip resurfacing or partial knee replacement have a lower success rate than older, more established methods, which replace the entire joint.
Despite success in most cases, one in seventy-five patients requires a revision of the joint replacement within three years of the original operation, the study by the Royal College of Surgeons found. The researchers said that newer surgical joints, which are designed to offer greater mobility and quicker recovery times, could be twice as likely to fail than standard ones.
Hip and knee replacements are among the most common operations done on the NHS, with about 160,000 carried out in England and Wales in 2006, mainly on sufferers of osteoarthritis.
Many patients need to have second or even third operations because plastic, ceramic or metal prosthetic joints can wear out after 10 to 15 years. But the study, which is published in the journal PLoS Medicine, found that some patients – particularly those who had hip resurfacing and so-called unicondylar knee replacements – needed to have their operations redone much sooner.
In hip resurfacing doctors replace just the surface or one side of the faulty joint instead of the whole ball and socket. Similarly in unicondylar knee replacements, doctors replace only one side of the knee joint.
The researchers analysed nearly 170,000 procedures carried out between 2003 and 2006, equivalent to about half of all operations performed in England in this period. They found an overall revision rate of 1.4 per cent, or about one in seventy-five people. Yet hip resurfacing had a revision rate of 2.6 per cent compared with 0.9 per cent for whole joint replacements cemented to the bone. Unicondylar knee replacement had a revision rate of 2.8 per cent, exactly twice the failure rate of a cemented joint.
The highest revision rates were among women who had undergone hip resurfacing, which could be explained by them having on average, weaker bones than men, the researchers said.
Jan van der Meulen, of the London School of Hygiene and Tropical Medicine, who led the study, said: “On the basis of our data, consideration should be given to using hip resurfacing only in male patients and unicondylar knee replacement in elderly patients.” The findings matched those from other countries, he added. Gordon Blunn, a biomedical engineer at University College London, said that hip resurfacing was often deemed appropriate for patients in their forties and fifties. “About 50 per cent of hip replacement patients in this age group have resurfacing and the revision rate is about 5 per cent after eight years,” he said.
Graham Gie, a consultant orthopaedic surgeon, was not surprised by the failure rates. “Hip resurfacing has only been around since the Nineties but it has been directly marketed to younger patients, in particular, as offering them a more active lifestyle following surgery,” he said.
“There isn’t really the long-term evidence to back those claims up, while at the same time the metal on metal joint has created another type of failure – fracture of the femur.”
Courtesy: http://www.timesonline.co.uk
