The meniscus is a C-shaped cartilage structure in the knee that sits on top of the leg bone (tibia). Each knee has two menisci, an inner and outer meniscus. The meniscus functions like a cushion between the rounded thigh bone (femur) and flat tibia. It also serves to help distribute the forces between the two bones over a greater area (rather than point to point), helps supply nutrition to the cartilage that lines the bones (articular cartilage), and helps stabilize the knee. The meniscus is a rubbery tissue that loses its elasticity with age. Nonetheless, each individual meniscus can be torn. Meniscus tears are very common, occurring in up to one third of all sports injuries. The inner or medial meniscus is injured most often.
Signs and Symptoms
• Pain or tenderness with standing, squatting or kneeling on the affected leg as well as tenderness along the joint of the knee.
• Swelling which can start right after injury, but up to 1 to 2 days after.
• Locking or catching of the knee joint, causing an inability to straighten the knee completely. Giving away or buckling of the knee.
• Direct insult to the knee such as trauma including twisting, pivoting, or cutting (rapidly changing direction while running).
• Contact sports (football), sports in which cleats are used with pivoting (soccer) or sports in which good shoe grip and sudden change in direction are required (racquetball, basketball, squash)
• Previous knee injury
• Associated knee injury, particularly ligament injuries such as a combined anterior cruciate ligament (ACL) tear.
• Poor physical conditioning (strength and flexibility)
• Year round sports
• A torn meniscus does not usually heal itself unless the tear is small and located in the outer portion of the meniscus where the blood supply is. However, the only definitive treatment for meniscal tears requires surgery. Surgery may provide complete healing over a period of 6 months combined with physical therapy. If the meniscus does not heal, it may need to be removed; it does not regenerate (grow back). Once removed, it’s gone.
• The success of a meniscus repair is about 80% when the anterior cruciate ligament (ACL) is intact. If the ACL is not reconstructed, success decreases to less than 40%.
• Because the function of the meniscus is to distribute joint forces and cushion, loss of meniscus is associated with early development of arthritis in the knee joint. Thus, the goal of surgery is to eliminate symptoms while trying to save the meniscus and protect the underlying cartilage. Removing the meniscus should be the last and only option.
• Frequent recurrence of symptoms, resulting in a chronic problem; appropriately addressing the problem decreases frequency of recurrence.
• Repeated knee injury, particularly if sports are resumed too soon after injury or surgery.
• Progression of the tear (the tear gets larger) if untreated.
• Arthritis of the knee in later years (with removal of meniscus or without surgery).
• Injury or destruction of the articular cartilage which lies under the meniscus.
• Complications of surgery, including infection, bleeding, injury to nerves (numbness, weakness, paralysis) continued pain, giving way, locking, non-healing of meniscus (if repaired), need for further surgery, and knee stiffness (loss of motion).