In the world of prosthetic hips, what was old is new again. A procedure known as hip resurfacing, once tried two to three decades ago, is experiencing a resurgence in the U.S., thanks to improved technology.
The new technique has several advantages over standard total hip replacement (THR) and is an attractive alternative to many people, said Peter Brooks, M.D., a Cleveland Clinic orthopedic surgeon, according to Cleveland Clinic's Men's Health Advisor.
“I think it's probably preferable in the right patient,” he said. “They absolutely love it. They love the concept.”
However, the procedure isn't for people with weak bones or kidney problems, so it may not be ready to supplant THR as the gold standard in hip prostheses. What's the difference?
In hip resurfacing, a surgeon shaves the head of the femur (the large thigh bone) where it connects to the hip socket (acetabulum). A metallic cap covers the femoral head, guided by a small, short stem drilled into the bone. The capped bone fits into a metallic cup inserted into the acetabulum.
A THR requires the removal of the entire femoral head and neck, replaced with a metallic device with a ceramic or metallic head and a long, thick metal stem that's driven deep into the femur.
The hip resurfacing devices of the 1970s and early 1980s, which used a metallic femoral head and a thin plastic socket, had a high failure rate, and by the mid-1980s, hip resurfacing had largely fallen out of use. A new metal-on-metal resurfacing device has been used in tens of thousands of patients worldwide for more than a decade, but it received U.S. Food and Drug Administration approval only in May 2006. Other devices are awaiting FDA approval.
The advantages
Whereas THR replaces the entire femoral head and neck, resurfacing preserves bone and targets only the problem area: the arthritic surface of the femoral head and acetabulum.
The long stem of a THR alters the natural biomechanics of the hip, resulting in a gradual thinning of the bone at the top of the femur that makes a follow-up THR difficult. Resurfacing preserves the normal hip mechanics and femoral thickness, delays the need for a THR and can easily be converted to a THR should it fail, Dr. Brooks said.
The larger head of the hip resurfacing system makes it more difficult to dislocate, and resurfacing patients generally do not have to follow all the precautions—such as avoiding bending forward more than 90 degrees or crossing their legs—that their THR counterparts must do to prevent dislocation in the weeks after surgery.
Dr. Brooks' patients also have reported that resurfacing feels more natural than a THR.
“I have a number of patients who have a hip replacement on one side and hip resurfacing on the other, and they uniformly prefer the hip resurfacing,” he said.
The disadvantages
Despite these pluses, resurfacing has drawbacks. In about 1 to 2 percent of cases, a fracture may develop at the femoral neck, just below where the new metal cap ends. The fractures, which usually occur within four months of surgery, sometimes can be repaired with pins, but a THR may be necessary if the fracture does not heal.