New hip and knee replacements may wear out in just three years

Thousands of patients who have their hips resurfaced or a new type of knee replacement may need to have them changed within three years.

Those having the latest medical procedures were more likely to need further corrective surgery down the line, according to a study by the Royal College of Surgeons of England.

The failure rate of a total hip replacement (l) is 1/111. The failure rate for hip resurfacing is 1/38

The researchers looked at data for 327,557 hip or knee replacement procedures carried out between April 2003 and September 2006 in the National Joint Registry.

They found overall one in 75 patients needed their joint replacement revised within three years of the first operation. This was comparable with other developed countries.

However, they found those who had a total hip replacement only had a 1in 111 chance of needing corrective surgery. This compared to 1 in 38 of those who had their hip resurfaced.

In a traditional hip replacement the entire head of the thigh bone is replaced with a ceramic or metal ball. This fits into a ceramic, metal or plastic socket in the hip bone.

But in hip resurfacing a cap of metal alloy is fitted over the thigh bone head and this connects into a metal socket grafted on the hip bone.

The authors of the study, published in the journal PLoS Medicine, found revision rates were particularly high in women, possibly because they have weaker bones on average compared to men.

Jan van de Leulen who led the study said: 'On the basis of our data, consideration should be given to using hip resurfacing only in male patients.'

Graham Gie, a consultant orthopaedic surgeon said hip resurfacing had been directly marketed to younger patients as offering a more active lifestyle after surgery.

'There isn't really the long-term evidence to back those claims up,' he said.

'While at the same  time the metal on metal joint has created another type of failure - fracture of the femur,' he added to The Times.

Researchers also looked at the newer type of knee replacement - unicondylar - which was introduced in the mid-1980s and involves only replacing the damaged knee compartment rather than the whole knee.

In conclusion, the study authors said: 'The highest rates after hip replacement were seen in patients who had undergone hip resurfacing and the highest rates after knee replacement in patients who had a unicondylar prosthesis.'

"Revision rates after hip resurfacing were especially high in women. It is essential to continue following up these patients to assess whether these differences remain beyond the first three years, because it has been shown that risk factors for revision as well as reasons for revision change with time after the joint replacement."

The research was the first ever study of joint replacement, tracking over half of all such operations carried out on the NHS in England over the period.