Orthopedics – Treatment Options

Feb 18, 2007

Doctors are beginning to offer a new alternative to hip replacement — one aimed at younger, athletic baby boomers who have worn out their joints too soon. Now they no longer have to wait until they hit their 60s for a fix. It is called hip resurfacing, covering a damaged hip’s ball and socket with smooth metal rather than cutting away worn bone and replacing it.

The operation hit the U.S. market last spring with Food and Drug Administration approval of the British-designed Birmingham Hip Resurfacing System. It isn’t the first time orthopedic surgeons have tried resurfacing worn-out hips. But where earlier attempts failed, data from Europe suggest this latest approach uses longer-lasting materials — with the additional promise of a joint that may hold up to the heavy recreation of today’s 40- and 50-somethings better than traditional hip implants.

Not everyone’s a good candidate, specialists caution. Resurfacing isn’t for patients with thinning bones — part of the joint could break — or those who have poorly functioning kidneys that can’t eliminate microscopic metal particles produced when the joint’s reinforced pieces rub together.

Moreover, while patients typically recover quickly, resurfacing is harder to perform than a hip replacement, and only a small fraction of the nation’s orthopedic surgeons so far are trained to do it.

But interest is growing, as evidenced by a focus on hip resurfacing at the annual meeting of the American Academy of Orthopaedic Surgeons — and a growing demand for hip repair from ever-younger patients.

Until now, “you might have told someone to soldier on for as long as you possibly can,” because a standard hip replacement before age 60 is itself likely to wear out, explains academy spokesman Scott Rubinstein of the Illinois Bone and Joint Institute.

With the new resurfacing option, “people may be a little more aggressive” in treating younger creaky joints, he adds. More than 400,000 total or partial hip replacements are performed each year, a number growing as the population ages.

Typically, surgeons replace a hip by cutting off the femoral head, the joint’s ball, and replacing it with a metal ball mounted on a rod implanted deep in the thigh bone. A plastic socket replaces the original. Those artificial hips can bring tremendous relief to people crippled by hip pain.

But the metal-on-plastic friction means the implants can begin wearing out in about 15 years, sooner if sports or other activities increase pressure on the joint. For the average 65-year-old, that’s no problem. A 50-year-old, in contrast, could very well wear out an initial replacement and have little thigh bone left to fit another.

“You’re dealing with Swiss cheese,” is how hip replacement pioneer Mitchell Sheinkop describes the remaining bone.

Enter resurfacing. Surgeons lightly shave the damaged femoral ball and fit a metal ball snugly over it. That ball rolls in a metal cup reinforcing the socket. The idea: Metal-on-metal shouldn’t wear out as fast, and if patients do need another replacement in 15 or 20 years, the thigh bone is largely intact.

“This resurfacing initiative has interest because we’re sparing bone,” explains Dr. Sheinkop, a Rush University professor and joint replacement director of the Neurologic and Orthopedic Institute of Chicago. What’s the evidence? The FDA cited studies showing the Birmingham Hip resurfacer lasted at least five years, approving its sale on condition that manufacturer Smith & Nephew Inc. continue tracking its endurance for 10 years.