I'm just starting to research the idea of a metal hip joint resurfacing procedure. What can you tell me about this treatment?

Hip resurfacing arthroplasty is a type of hip replacement that replaces the arthritic surface of the joint but removes far less bone than the traditional total hip replacement.

Because the hip resurfacing removes less bone, it may be used for younger patients. Hip joint resurfacing is a good idea for those who are expecting to need a second, or revision, hip replacement surgery. The need for a revision operation increases as they grow older and wear out the original artificial hip replacement.

During the procedure, the femoral head is dislocated out of the socket. Special powered instruments are used to shape the bone of the femoral head so that a new metal surface will fit snugly like a cap on top of the bone. The cap is held in place with a small peg that fits down into the bone. The hip socket may stay the same, but more often it is replaced with a thin metal cup.

The patient must have enough healthy bone to support the cap. The metal materials hold up well under the increased activity of a younger adult group of patients. There is a lower risk of hip dislocation after joint resurfacing compared with a total hip replacement. This may be because the fit is so much closer and better for hip resurfacing.

There have been some problems with metal-on-metal hip joint resurfacing. For example, tiny pieces of metal can fleck off the implant with prolonged wear and tear. Those metal ions can create irritating debris in the joint contributing to increased wear and tear.

Long-term reports of metal-on-metal hip resurfacing are fairly limited in number. Future research efforts are needed to observe the natural history after hip joint resurfacing and report on long-term results.

One study after 12-months reported a 75 per cent satisfaction rate. But this means that one-quarter of the patients were not happy with the results. Factors contributing to suboptimal recovery are unknown. It could be a lack of rehabilitation after the operation. It could be a different type of rehab is needed for hip joint resurfacing.