Harvard Medical School Adviser by the Faculty of Harvard Medical School

Q:

I am 72 years old and in good health. I've had left knee pain on and off for almost six months. It's not too severe, but it aches if I walk more than a mile or so. I also sometimes get sharp pain when climbing stairs. My doctor sent me for an MRI of both knees. It showed "mild to moderate osteoarthritis" in both knees and a torn meniscus in my RIGHT knee, which feels fine. I think I know what to do about my painful knee -- but what should I do for the torn meniscus in my "good" knee?

A:

Before we get to your interesting question, some background information may be helpful.

The meniscus is a crescent-shaped disk of fibrous tissue and cartilage. Each knee has two menisci located between the femur (thighbone) and tibia (lower leg bone); one is on the inside of the joint, the other on the outside. Together, the menisci act as shock absorbers, protecting the other cartilage tissue that covers the end portions of the femur and tibia.

As you age, the menisci weaken and fray. Even such a simple motion as getting in and out of a squatting position or rising from a low chair can tear a meniscus.

Your osteoarthritis diagnosis is a separate issue from your meniscal tear. Again, some background: Osteoarthritis is the most common form of arthritis, involving damage to the cartilage that covers the end of the bones. As it progresses, it can lead to abnormalities in the bones themselves.

Osteoarthritis, the most common form of arthritis, involves damage to the cartilage that covers the end of the bones. As it progresses, it can lead to abnormalities in the bones themselves. Ordinary X-rays can diagnose arthritis in the knee, but MRIs are necessary to evaluate the menisci. As MRIs have come into widespread use, arthroscopic meniscal surgery has become the most common orthopedic operation in the United States.

A torn meniscus can cause pain, and surgery can help. But MRIs are so sensitive that they often detect abnormalities that are not causing any clinical problems. It's a well-known issue in many parts of the body, but does it also apply to the meniscus?

To find out, doctors in Massachusetts performed MRIs on the knees of 991 people between the ages of 50 and 90. The subjects were chosen at random, and researchers didn't know whether or not they had any knee symptoms.

These MRIs found that meniscal damage was common. The prevalence ranged from 19 percent in women ages 50 to 59, to 56 percent in men ages 70 to 90. Meniscal tears became more common with increasing age. And they were more common in people who had knee arthritis than in people who didn't.

None of these observations were surprising. But another finding was unexpected, and it relates directly to your question. Meniscal tears were nearly as common in people who had no knee pain as in those with painful knees. In people who also had knee arthritis, 63 percent with knee pain had tears and 60 percent who were pain-free had tears. In people with no arthritis, 32 percent with pain had tears and 23 percent without pain had tears.

Doctors should always treat patients, not X-rays or MRIs. Since your right knee feels fine, there is no need to treat the meniscal tear. But if you had pain, the decision would be more difficult, since it would be hard to know if your pain was caused by the arthritis, the tear, or both. If your symptoms were mild, it would probably be best to treat the arthritis first, keeping meniscus surgery in reserve in case your symptoms got worse.

That brings us to your painful, arthritic left knee. A standard program would include limiting high-impact exercise, bending and kneeling. Applying ice after activity may help. A knee brace, even a simple drugstore knee sleeve, can provide beneficial support. Most doctors recommend acetaminophen (Tylenol and other brands) for pain relief, with nonsteroidal anti-inflammatory drugs, such as ibuprofen (Motrin and other brands) and naproxen (Aleve, generic) as the next option. Finally, muscle-strengthening exercises can take pressure off your knee joint and reduce pain and stiffness.

Strengthening the muscles around your knees and maintaining their power reduces stress across the joint. Muscle-strengthening exercise can help you improve flexibility around your knee and build up supporting muscles. Further, building adequate strength and flexibility around the knee makes you less susceptible to bursitis and tendinitis.

It's a long answer to your question, but there is a short answer, too. It's the time-tested adage: If it ain't broke, don't fix it.

(Submit questions to harvard_adviser@hms.harvard.edu.)

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