Knee Replacements: Are You Too Young, Too Old, Too Fat, or Too Active?

US News & World Report—March 12, 2010

Getting a new knee because the original has worn out and may have become painfully arthritic is an increasingly common surgery in America. First-time knee replacement surgeries rose 63 percent between 1997 and 2004, according to a 2008 paper in Arthritis Care & Research.

Findings coming out of the 2010 American Academy of Orthopaedic Surgeons annual meeting this month are shedding helpful light on knee replacements, including how active one can be with an artificial knee, how young or how old one should be to undergo the surgery, and the varying benefits to be gained.

When patients and their doctors decide whether to proceed with a knee replacement, "It's always a quality-of-life issue," says Mark Figgie, M.D., chief of the Surgical Arthritis Service at Hospital for Special Surgery in New York. Osteoarthritis, which causes the cartilage in joints to wear away, is the usual culprit when knee pain has made walking painful. Even sleeping can be very uncomfortable—sometimes unbearably so—because a day's worth of moving around has inflamed the joint. And being unable to enjoy the activities you once did—say, golf or cycling—also can be a quality-of-life factor, says Figgie.

The results of a knee replacement vary with the health of the patient, but generally show improvement in the quality of life area. Weight can be a factor in the success of the replacement. Figgie notes that generally speaking, people who do best after a knee replacement are in good shape: "It's better to be fit than fat," he says. 

And older knee replacement patients may reap the added benefit of improved balance, according to other research coming out of this year's AAOS meeting. Israeli researchers found that subjects with an average age of 73 who had total knee replacements enjoyed significant improvements in balance, pain, and self-reported quality of life. With age and "as patients get more and more deformity [in the knee joint], it gets more painful," says Figgie, who was not involved in the research. As the study showed, he adds, post-knee replacement patients again have a straight knee and the ability to fully flex the joint. This provides them more stability, which improves their walking and, of particular importance to older folks, reduces the risk of falling. As long as patients are healthy enough to withstand the effects of surgery, he says, they are not too old to have a shot at improved quality of life with a knee replacement.

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