Tuesday, February 13, 2007

The Problem For those with older or injured knees, it hasn't been clear if weight-bearing exercise helps or hurts. Some small studies have suggested it might protect against osteoarthritis (OA), perhaps by building cartilage; others have found the opposite. "There has been a lot of discordance and confusion in the literature about 'Can you?/Can't you?' " says David Johnson, an orthopedic surgeon and sports medicine specialist at Washington Hospital Center. Until now. According to a study in the journal Arthritis Care & Research, moderate exercise has no effect -- positive or negative -- on the development of OA in the knee, even for people who are overweight or obese.

The Study The study, led by Boston University School of Medicine professor of medicine and epidemiology David T. Felson, involved nearly 1,300 participants who were examined once, when their age averaged 53, and again nine years later. Each time, they were asked how much they exercised and whether they had knee pain, and X-rays were taken of their knees. The data showed no link between exercise and arthritis. Concluded the researchers, "Physical exercise can be done safely without concerns that persons will develop knee OA as a consequence."

Osteoarthritis wears away cartilage, a protective tissue that eases the movement of joint bones, causing those bones to rub together painfully. Two major risk factors for OA are injury and family history. ("My father had it," Johnson says, "and now I do.") It usually develops after age 45.

The Reaction Johnson says the findings will immediately change what he tells his patients. "I am beset by patients who need to be active but who are afraid they are going to develop OA if they exercise," he says. "This article gives us the green light to tell patients they can and should" exercise.

-- Matt McMillen

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