THERE is nothing like a new hip or knee to put the spring back in your step. Patients receiving joint implants often are able to resume many of the physical activities they love, even those as vigorous as tennis and hiking. No wonder, then, that joint replacement is growing in popularity.
In the United States in 2007, surgeons performed about 806,000 hip and knee implants (the joints most commonly replaced), double the number performed a decade earlier. Though these procedures have become routine, they are not fail-safe.
Implants must sometimes be replaced, said Dr. Henrik Malchau, an orthopedic surgeon at Massachusetts General Hospital in Boston. A study published in 2007 found that 7 percent of hips implanted in Medicare patients had to be replaced within seven and a half years.