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Conditions Expert Dr. Otis Brawley Chief Medical Officer,
American Cancer Society

Expert answer

The meniscus is a crescent-shaped pad of fiber and cartilage. There are two in each knee sandwiched between the tibia (bone of the shin and lower leg) and the femur (the bone of the thigh or upper leg).

Their purpose is to distribute the force of weight placed on the knee while walking and running. The meniscus stabilizes the knee during rotation, and lubricates the knee joint.

A meniscal tear is a very common injury. Traumatic tears occur most often from twisting motions commonly found in soccer, football, basketball and other sports. Older patients are more subject to degeneration of the meniscus and can be prone to tears with minimal twisting or stress.

There may be little or no pain at the initial injury and athletes often continue playing after a meniscal injury. Within a day or so after the tear, there is usually pain, swelling and stiffness of the knee.

A large tear can impair the smooth bending motion of the knee and cause locking, catching or "giving out" of the knee. A smaller tear can be perceived simply as instability of the knee.

A health care provider may make a presumptive diagnosis through history and physical examination or may do imaging with ultrasound or magnetic resonance imaging.

Some patients may also get the definitive diagnosis through exploratory arthroscopy, which is a surgical procedure in which a scope is placed in the knee allowing the surgeon to directly see the meniscus.

Initial therapy of a torn meniscus in a stable knee involves avoiding things that cause pain. One should apply ice to the knee 15 minutes every four hours and elevate the knee.

Crutches and a leg cuff may be needed to enable walking without pain and protect the knee from unnecessary bending and twisting. Nonsteroidal anti-inflammatory drugs, such as ibuprofen, are also useful.

After the initial inflammation subsides, exercises to strengthen the quadriceps and hamstring muscles of the upper leg are usually prescribed. This is best done under the supervision of a physical therapist.

Conservative therapy with muscle strengthening is frequently all that is needed for minor tears in which good knee function returns as inflammation subsides.

The meniscus has very little blood flow, and it often does not heal. Some patients getting conservative therapy for an old tear may have an occasional knee problem and may eventually choose to have surgical treatment.

Candidates for early surgery are patients who have persistent difficulty after the initial inflammation subsides. These patients are often unable to bear weight, have restricted knee movement, have continued pain or have other knee problems such as ligament damage. These patients generally have larger, more complex tears.

The meniscal surgery may be a repair of the tear or removal of part or all of the meniscus. The operation is most often done by arthroscopy, but in some instances has to be done through an open procedure with a larger incision.

Long-term, patients with untreated tears of the meniscus or who have removal of part or all of the meniscus are at increased risk for osteoarthritis.