Alan M. Reznik, M.D.
The Medial and Lateral meniscal cartilages are gasket like cushions in the knee. Positioned between the femur and tibia, they distribute the weight transferred from the larger femur above to the smaller tibia below. The Menisci also help with the stability of the knee joint. Healthy Menisci convert the relatively flat tibial surface into a more stable shallow socket
Meniscal tears can occur in any age group. In younger people, the meniscus is a fairly tough and rubbery structure. Tears in the meniscus usually occur as a result of a forceful twisting injury or with hyperflexion of the knee. In younger age groups, meniscal tears are more likely to be caused by a sports injury. In more mature individuals, it can occur with squatting down, twisting or a fall. In older individuals, the meniscus can be weaker and easier to tear. Sometimes meniscal tears can occur as a result of a minor injury, even from the up and down motion of simple squatting. Degenerative tears of the meniscus can also be seen as a part of osteoarthritis of the knee, gout and other arthritic conditions.
In many cases, knee pain is the most common complaint and the patient cannot recall one clear associated injury that leads to the meniscus tear. The pain may be felt along the joint line where the meniscus is located. Sometimes the symptoms are much more vague and occasionally they involve the whole knee. If the torn portion of the meniscus is large enough, locking may occur. Locking simply refers to the inability to fully straighten the knee or loss of the ability to move the knee. Locking occurs when a piece of torn cartilage, or meniscus, is stuck between the bones (see the picture above). In other words, the meniscus is caught in the hinge mechanism of the knee. Once stuck, it will not let the knee straighten out or move completely. (To see Dr. Reznik's video, "The Locking Knee", go to Youtube.com/DrAReznik.)
Left alone, over time the locking and/or constant rubbing of the torn meniscus on the articular cartilage will cause damage or degeneration of the knee joint. As a result, the knee may also become swollen, stiff and tight.