How to appease your knees - preventing knee injuries

Nation's Business, May, 1993 by Marcia J. Pear

Picture a round ball sitting on a flat surface, held in place by rubber bands. Now imagine that you use that ball during virtually every waking activity. The odds of its wearing out will seem high.

That ball is the knee joint; the rubber bands holding it in place are ligaments, muscles, and tendons. Normal walking involves subjecting your knee joint to force equal to six times your body weight--a 150-pound man applies 900 pounds of pressure to his knees with every step. Yet by its very design, the knee lacks inherent stability, making it highly vulnerable to injury.

An estimated 50 million Americans suffer from knee pain. Each year, more than a million people undergo knee surgery to remove torn cartilage, the elastic connective tissue that covers and protects the ends of bones. And once the knee has been hurt, the chances of re-injuring it increase.

"The knee wasn't built for the types of activities we subject it to, like football, basketball, tennis, and step aerobics," says James M. Fox, attending surgeon at the Southern California Orthopedic Institute in Van Nuys, and author of Save Your Knees (Dell Publishing).

"People get into trouble because they don't prepare themselves for an activity," he says. "The time to get in shape for a sport is three months ahead of time, but many people try to get ready for their company's softball team by stretching right before the game starts."

The most common knee injuries are tendinitis, which is an inflammation of the soft tissues, or tendons, that surround the knee joint; and chondromalacia (literally, "cartilage wear"), an irritation or blistering, usually on the undersurface of the kneecap. Both conditions can arise either from overuse (for example, going on a 20-mile bike ride instead of your usual two miles) or exercising on a harder-than-usual surface.

The best way to head off knee trouble is to build up the muscles that support the knee. "Just as the guide wires on a sailboat relieve stress on the mast, the muscles on the front and back of the leg, known as quadriceps and hamstrings, respectively, take pressure off the knee joint," says Fox. The key is developing appropriate muscle strength and endurance.

Nadine M. Fisher, clinical assistant professor of rehabilitation medicine at the State University of New York at Buffalo, conducted a research study with people ages 20 to 80 who had osteoarthritis of the knee. In younger patients, the problem was mainly due to sports injuries; in older people, to general wear and tear.

Fisher's program began with simple isometric exercises (contracting a muscle and holding it tightly for a brief period) and progressed to full resistance training, targeting the quadriceps and hamstring muscles. After several months, 90 to 95 percent of participants had less pain and increased functional capacity, she says. "Once you've gained sufficient strength in your muscles and want to maintain it, a good exercise is climbing up and down flights of stair's."

Although the vast majority of knee problems can be managed successfully with a good rehabilitation program that includes strengthening, conditioning, and possible changes in footwear, a small percentage of people with irreparable cartilage damage may be candidates for surgery. Eugene M. Wolf, an orthopedic surgeon with California Pacific Medical Center in San Francisco, says: "Removing the cartilage is like taking the shock absorber out of your car. It's only a question of time before you start seeing uneven wear on your tires. If you lose your cartilage at a young age and continue to be active, by the time you're 40-something you can have a painful arthritic knee."

Until recently, surgery to remove torn cartilage was the best option for people with severely worn "shocks." Now, a new approach is shifting the emphasis from cartilage removal to repair

Cartilage transplants using frozen tissue from cadavers are currently being performed by a handful of orthopedic surgeons around the country, including Wolff "This is preventive surgery to halt degeneration of the knee," says Wolf.

Wolf recalls that "a 30-year-old woman who had injured her knee in a skiing accident had cartilage-transplant surgery 18 months ago. Recently, I looked at the inside of her knee using an arthroscope [a cameralike surgical instrument that illuminates the inside of a joint] for the first time since the operation, and her knee looked completely normal. She no longer has pain. She's playing tennis."