What causes my knees to pop when I walk? I am afraid that running or walking daily for two miles has caused this. Would stretching be beneficial? It's embarrassing to have noisy knees!

If you don't recall a specific event (like stepping off a curb or into a hole, twisting your knee and hearing a pop), and you're not having any pain, what you're experiencing may be normal wear-and-tear. This means the gradual wearing down of the cartilage (the meniscus) that cushions the knee. The rough edges of micro-tears rubbing against each other can cause that noise, as can minute pieces of cartilage that have broken away and are floating in the knee capsule.

You may also have the beginnings of chondromalacia patella, the wearing away of the smooth underside of your kneecap as your kneecap rides over the bones of your thigh (femur) and lower leg (tibia).

Although there is cause for concern, don't panic. If you're not experiencing pain, your knees aren't swollen and your mobility is not limited, monitor your situation for another week or two. If you feel pain or instability walking up or down stairs, feel like your knee is going to give out or lock, or feel like you can't straighten it, see an orthopedic surgeon immediately. Even if you're not experiencing any of these, don't put off seeing a surgeon. You don't want a minor tear to become a major one. These days most damage to the meniscus can be repaired arthroscopically.

You may also try strengthening your legs and doing more stretching to maintain the proper balance between your quads and hamstrings. Do leg extensions and leg curls in the gym at least twice a week. (I strongly urge anyone with knee problems to maintain a gym membership in order to use those two leg machines.)

Stretching the muscles of your legs is always a good thing to do. Knee problems can be brought on or exacerbated by tight quadriceps, hamstring, and calf muscles -- all areas that get tighter when we use our legs for exercise.

A good book on stretching is Sport Stretch by Michael Alter. If you can't find it at your local bookstore, you can order it from the Perform Better catalog (800-556-7464). Avoid walking on hilly terrain or up and down stairs until you get this sorted out.

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