The meniscus is a ring shaped piece of tissue that acts as a cushion, or gasket between the thighbone (femur) and the shinbone (tibia). It functions as a shock absorber, distributing stress across the knee joint. It also acts to aid in smooth hinge-like knee motion. There are two menisci in the knee joint; one in the inside of the knee (medial meniscus) and one in the outside of the knee (lateral meniscus). Either of these structures may become ripped, or torn.
Common Causes
Pivoting or twisting, squatting or kneeling activities. Often there is some trauma to the knee, but many meniscus tears are ‘degenerative’ or simply occur as part of the aging process.
Symptoms
Pain in the knee, especially with squatting or kneeling, getting up out of a chair, getting in and out of a car, etc. The pain may be sharp, in the back of the knee. Patients may report clicking, or a sense of catching inside of the knee. Frank locking of the knee is highly suspicious of a certain type of meniscus tear. There may be intermittent swelling.
Physical Findings
Tenderness along the joint line of the knee, either medially or laterally. A sense of clicking with the knee flexed and rotated is suspicious for a meniscus tear.
Workup
Often the diagnosis is made solely on history and physical examination. MR scans are fairly accurate in detecting these injuries, if the diagnosis is uncertain.
Non-operative Treatment
Rest, anti-inflammatory medication, and physical therapy may improve symptoms to a very tolerable level.
Surgical Treatment
An operative arthroscopy, with either trimming of the torn piece of meniscus, or an arthroscopic meniscus repair.
Injury Comment
These are common injuries, especially with sports and in an increasingly active middle-aged population. Not all patients require an arthroscopy, but if surgery is required, the success rate is high.