Strengthen your thigh muscles
In a 2009 study of 265 men and women with knee osteoarthritis, Mayo Clinic researchers found that those with the strongest quadriceps (thigh muscles) had less knee pain and better physical function than those with the weakest. But there's a right way and a wrong way to build those muscles. If you're an avid gym-goer, avoid the leg-extension machines, Kenny suggests. "They put far too much stress on the knee joint," he says.
Maintaining flexibility is important, especially in the muscles and tendons that connect directly to the knee, such as the hamstrings and the quadriceps. If these tissues become overly taut, they can pull the knee out of alignment.
Lose the weight, finally
Losing as little as 5 percent of your body weight can dramatically reduce your chances of developing knee arthritis, the most common cause of knee pain, according to the authors of a study presented last November at a meeting of the American College of Rheumatology.
Many doctors recommend taking 1,500 milligrams (mg) of glucosamine and 1,200mg of chondroitin daily to strengthen aging cartilage. Their use is controversial because no studies have proven they work. But no studies have found a downside, either. "I firmly believe that this helps," Nicola says.
Get to the doctor — pronto — if your knee is swollen
Likewise, a rattling, grinding noise, or a feeling of gravel moving around inside your knee, should prompt a visit to the doctor. These can be early warning signs of damaged cartilage. Fortunately, several techniques have been developed in the past few years to repair worn cartilage, including autologous chondrocyte implantation: a surgeon suctions out some of your living cartilage cells, grows millions of copies of them in the lab, then reinjects them into your knees. The technique is new — and is best used on tiny areas of worn cartilage. But researchers believe so-called tissue engineering could one day offer relief even for those with full bone-on-bone arthritis.
If your doctor recommends surgery right away, seek a second opinion
"I personally think there's more knee surgery being done these days than is warranted," says Kenny, himself a retired surgeon. Several major studies of arthroscopic surgery to remedy sore knees have found little or no benefit. Physical therapy, as well as anti-inflammatory medicines, can be just as effective — and less invasive.
After that fateful day on the tennis court, Linda Morse visited an orthopedic surgeon, who diagnosed a tear in her meniscus and scheduled her for surgery. But when he went into her knee, he found no tear—just a little arthritis. Since then, Morse has dedicated herself to protecting her knees. She exercises regularly, keeps her build lean, and doesn't play on hard tennis courts anymore. "It's made me diligent," she says of her injury scare. "Today I feel like I have the knees of a 40- or 50-year-old."
Gretchen Reynolds writes the Phys Ed blog for The New York Times online. For black-and-white reprints of this article, call 866-888-3723.