General Information
The menisci are structures made of a material called fibrocartilage which serve as shock absorbers between the femur (thigh bone) and the tibia (shin bone). The menisci also to help maintain knee stability and facilitate joint lubrication and normal knee function. Tears can occur in patients of all ages. Tears often occur with twisting type activities but the exact mechanism of injury can be quite variable. At times patients can not remember the specific injury which caused the tear.
Symptoms of torn menisci include knee catching, swelling, locking, and/or pain. Locking means that the knee can catch unpredictably or "lock" in one position (usually in a bent position). Just as suddenly the knee can become "unlocked", often with another snap and then feel better. Meniscal tears can sometimes cause knee pain without catching or locking and can be associated with knee swelling. Meniscal tears may be associated with other injuries to the knee such as ligament damage, fractures or degenerative arthritis but also may occur alone. If a meniscal tear is suspected based upon history and physical examination, after x-rays are used to evaluate other possible causes of the symptoms, MRI scan is often used to diagnose the tear. MRI scans are good but not perfect tests for meniscal tears. Sometimes patients have symptomatic tears that were not detected on MRI scans.
Occasionally meniscal tears heal by themselves. Sometimes a meniscal tear does not heal yet may not cause problems and is discovered only incidentally during treatment for another condition or at autopsy.
WHEN DOES A MENISCAL TEAR REQUIRE SURGERY?
If the torn meniscus produces problems such as catching, locking and pain over a period of weeks to months without gradual improvement, surgical treatment may be suggested. After an acute meniscal tear if the patient is unable to completely straighten his or her knee after one to two weeks and is not making improvement, arthroscopic surgery is usually indicated. In that instance the torn meniscus is caught in between the femur and the tibia in such a way that it forms a mechanical block to motion. Sometimes the meniscal tear is not so large as to cause the knee to be “locked” but causes persistent swelling and pain which requires surgery. Arthroscopic surgery can remove or repair the torn meniscus.
It is important to realize that there is a subset of meniscal tears called “degenerative tears” that happen in knees that also have arthritis. In these cases as the joint damage from arthritis progresses the meniscus which is in between the joint surfaces can become compressed and torn. In this type of tear, treatment of the associated symptoms and arthritis with time, medications, injection and exercise therapy has a good success rate. Not every tear that is diagnosed on MRI scan needs surgery, especially if it is a degenerative tear. Sometimes however, symptoms do not improve without surgery. In that case, one has to be very careful that the arthritis is not too severe or arthroscopic surgery can fail to improve or even worsen your condition.
SURGICAL OPTIONS
Depending upon the type and extent of the meniscal tear, the patient’s age and activity level as well as the possible pre-existing presence of degenerative arthritis appropriate treatment may include either removal of the torn meniscal fragment or repair of the meniscus.
Removal of the torn fragment of meniscus can generally be performed as out-patient surgery and requires usually only two small incisions in the front of the knee. Crutches are recommended for 2-3 days to limit pain and swelling. Return to school or work may be possible within several days. Full return to activity depends on associated conditions within the knee and with the individual’s level of motivation and dedication during his post-operative recovery. Generally return to full work or athletic function is possible within 4-6 weeks with an isolated meniscal tear when the tear is treated by removal of the torn fragment (menisectomy). In some cases patients feel fully recovered within 2 weeks.
If your torn meniscus is repairable, I believe that is the preferred procedure. Available medical information suggests that repair of the meniscus (rather than removal), when possible, results in a decreased incidence of degenerative arthritis years later. Meniscal repair can usually be accomplished with an arthroscopic technique. Often one additional incision of approximately of one to two inches in size is necessary in the back aspect of the knee in order to complete the arthroscopic repair. The success of arthroscopic repair in relieving the pain and catching symptoms is approximately 90%.
After meniscus repair patients must use a knee brace while walking for the first month. Crutches are needed for about 7-10 days. Menisci take time to heal and because of this we do not recommend return to sporting type activities or work activities that include squatting for at least three months after surgery. Although meniscal repair involves a more prolonged initial recovery I firmly believe that it is in the best long term interest of your knee to repair the menisci if possible.
ASSOCIATED CONDITIONS
At times other problems within your knee such as degenerative arthritis, ligament injury or loose pieces of bone, cartilage or even localized scar within your knee can simulate meniscal symptoms. During the course of your knee arthroscopy your knee will be thoroughly examined and all associated conditions will be treated as necessary. Occasionally the menisci will be found normal and treatment otherwise directed at removal of the offending ligament, bone, scar or cartilage tissue.