Each knee has two menisci — the lateral meniscus and the medial meniscus. The menisci are crescent-shaped pads of cartilage that serve as cushions between the femur (thigh bone) and tibia (shin bone). They help stabilize the knee joint and the distribute the forces of weight and impact upon the knee. The lateral meniscus is located on the outside of the knee.
Meniscal tears are common athletic injuries, particularly in sports such as tennis, basketball and football, but they happen to other people in other situations as well. Typically, the meniscus tears when it is subject to opposing forces. The upper part of the leg rotates or pivots in one direction, while the foot and lower leg remain planted in position. The injury may cause pain and swelling and make it difficult to straighten the leg.
Tears in the meniscus may be small or large. Sometimes it tears in more than one place. The extent of the damage determines the treatment. A minor tear with no lasting symptoms may be treated with physical therapy exercises to strengthen the muscles around the knee.
Sometimes the meniscus can be surgically mended. Young people tend to respond to this treatment the best, especially those who are very fit and whose knees are otherwise in good shape.
When repair is not possible, the surgeon may remove a section of the meniscus. Removal of the entire meniscus is now used as a last-resort method because it makes the knee more susceptible to arthritic degeneration.