The meniscus is a C-shaped cartilage between the thigh bone (femur) and the shin bone (tibia) in the knee. There are two meniscal structures; the medial meniscus (inside of the knee) and the lateral meniscus (outer side of the knee). The meniscus acts as a shock absorber and protects the cartilage of the knee joint, keeping it from wearing out and causing early arthritis. The meniscus also adds to the stability of the knee joint.
Causes for Meniscus Tears
Most injuries are sports-related. Most frequently this is a twisting-type force injury causing the meniscus to tear or rip and pinching it between the femur and the tibia. In some cases tears can be associated with a ligament rupture. Not all meniscal injuries result from sporst related activity. In some cases something as simple as getting up from a squatting position will do. Other meniscal tears occur gradually over time and in older patients these may represent degenerative meniscal tears and may not show any symptoms. The location of the tear within the meniscus may determine the type of treatment which is most appropriate.
An acute meniscal tear may be heard as a "pop" and feels as a tear or rip in the knee and within a few minutes to hours you can experience painful swelling of the knee. However, some injuries show little swelling and minimal pain or discomfort. Patients most often describe a popping or catching in their knee. Some actually can feel something out of place. In severe cases the knee will actually lock, preventing the patient from fully extending or straightening the knee -- or occasionally from flexing or bending it. The pain or discomfort is usually along the joint line or where the femur and tibia bone come together. It often starts out relatively painful; then with time, much (if not all) of the pain disappears except with certain activities. Some patients will have the tear become asymptomatic (no symptoms) for a time, especially if their activity level decreases significantly.
Very few meniscal tears will heal on their own, only very small tears that are in the outside of the meniscal tissue, and usually only in young patients, will heal on their own. Those tears associated with an unstable knee, such as when a ligament injury occurs, have a poorer prognosis due to their risk of re-injury. Treatment is individualized according to the symptoms and the patient's activity level. Some patients can live with a meniscal tear without significant worsening over time, others will not be able to function at their pre-injury level without treatment. There is no known medicine or therapy that will heal or fix a torn meniscus. It is a mechanical problem requiring a mechanical solution. This usually means either partial excision or repair of the tear. Excision versus repair is often decided at the time of arthroscopic surgery and will depend on the patient's age, the age of the tear, the size and location, as well as the patient's activity level. Because the the meniscus is an important structure in protecting the knee from early arthritis, repair is always preferable to removal.