Hip resurfacing has lost favor with many surgeons because it can increase the amount of potentially harmful metal ions in the bloodstream. It also has a risk of bone fracture just below the metal cap placed on the top portion of the thighbone — particularly in women with poor bone quality.

Unlike traditional hip replacement, hip resurfacing doesn't completely replace the "ball" of the hip with a metal or ceramic ball. Instead, the bone is reshaped and capped with a metal prosthesis. The hip socket is fitted with a metal cup.

As these metal surfaces rub together, there is the potential for wear and release of metal ions. This can cause reactions in some people.

The socket prosthesis for a traditional hip replacement is usually lined with a thick layer of hard plastic, so there isn't any metal-on-metal contact. However, the "ball" portion of an artificial hip is usually much smaller than what you're born with, so there's a higher risk that it might pop out of the socket (dislocate).

The risk of dislocation is much lower for hip resurfacing, because the ball portion of the joint can remain larger. This may make hip resurfacing a better choice for people who need to squat for work.

The best candidates for hip resurfacing are men under 60 who have strong, healthy bone. The risk of fracture is higher for older people, especially small-framed women whose bones have been weakened by osteoporosis.