Are your knees putting up a protest, creaking and aching at every step, keeping you awake at night and nearly immobile during the day? Fortunately, you don't have to take this lying down anymore.

Kitty Cornett has been a jock her entire life, playing hard at powder puff football, tennis, league-level soccer, competitive biking and jogging.

Now, at only 43, this Knoxville, Tenn., woman's knees are showing the strain: Injured and reinjured, pushed to the max many times, they've developed osteoarthritis (OA). Knee pain has made her give up the sports she loves, and her joint motion is so limited she even has trouble getting out of her car. "It's awful," she says. "I've gone from an active lifestyle to this. Today, I can't even walk around the block."

Kitty Cornett is one of 21 million people with osteoarthritis —an overwhelming number of them with knee OA. Sore knees are the reason for almost 11 million doctor visits a year. In 1999, some 267,103 of these knees ended up with a total joint replacement —97 percent because of OA, according to the American Academy of Orthopaedic Surgeons.

"There's an epidemic of knee OA, and it's taking a tremendous toll," says William J. Arnold, MD, a Chicago-based rheumatologist who specializes in knee OA and cartilage replacement.

Roland W. Moskowitz, MD, head of the Arthritis Research Institute at Case Western Reserve University Hospitals in Cleveland, and an OA and cartilage expert, agrees. "But we've made great strides toward new therapies and in the near future we expect to have even more," he says.

"Even 10 years ago, OA prevention and repair was the holy grail that we thought was unattainable. Now we are beginning to understand the process of the disease that allows us to directly target it, and keep OA from getting worse —or even repair cartilage," says Dr. Moskowitz.