Replace bad knees, get better heart?

Total knee replacement (TKR) in elderly patients with osteoarthritis (OA) may lower their risk of both heart failure and total mortality, suggests new research presented at this year s meeting of the American Academy of Orthopedic Surgeons.

Osteoarthritis, the most common form of arthritis, affects perhaps 30 million Americans to some degree and nearly everyone has some joint symptoms by age 70. Those with severely arthritic knees may be advised to undergo TKR, a surgery in which the damaged cartilage and bone are replaced with implants to improve the knee s motion. This surgery can be done on one or both knees, as indicated.

In order to assess the benefits of TKR in older OA patients, investigators used Medicare records to separate these patients into two groups: those who underwent TKR, and those who did not. Most significantly, the researchers found that TKR patients had half the risk of mortality, as well as a lower rate of congestive heart failure, when compared with patients who had not undergone the surgery. These results were true at three, five, and seven years after surgery.

Yet ACSH s Dr. Gilbert Ross wonders how accurately the study s outcomes actually represent the benefits of the TKR procedure itself, as opposed to reflecting the better health necessary to undergo the surgery in the first place. The investigators indicate that they controlled for underlying health problems, but Dr. Ross is skeptical that it's possible to truly account for all possible health differences in this case. And while he acknowledges that the increased mobility allowed by TKR might be responsible for some benefits to patients health, he doubts that it could account for such a radical decrease in the risk of mortality. It seems possible that the decrease may be due to selection bias. he says. That being said, as a former rheumatologist, I can attest to the often-miraculous improvement in mobility and general well-being derived from TKRs in appropriately-selected patients.