vessels, but each has a large central section which is avascular and does not get a direct blood supply. This poses a problem in a meniscus injury, as blood flow is diminished and the avascular areas tend to not heal. Injury The tear of meniscus is among the most common knee injuries. It is usually caused by torsional stress; twisting or turning of the knee too quickly with the foot planted on the ground while the knee is flexed. The feeling of a "pop" in the knee is usually felt when the meniscus is torn. Athletes, particularly those who participate in contact sports, are at a greater risk for meniscal tears. Sports-related meniscal tears often occur with other knee injuries, such as an anterior cruciate ligament tear. A torn meniscus is commonly referred to as torn cartilage in the knee. Menisci tear in different ways and are noted by how they look, as well as where the tear occurs in the meniscus. Two types of tears include minor, which includes stiffness and swelling within two to three days but usually goes away in two to three weeks. Then there is severe, which without treatment, a piece of meniscus may come loose and drift into the joint space. Tears include longitudinal, parrot-beak, flap, bucket handle, and mixed/complex. Epidemiology Injury to the medial meniscus is about five times greater than injury to the lateral meniscus due to its anatomical attachment to the MCL. Lateral meniscal tears are more common in acute ACL injuries, whereas medial meniscal injuries are more common in chronic ACL-deficient knees and more amenable to repair. Meta-analysis shows that in acute injuries of the ACL associated with a meniscus tear, 44% were of the medial meniscus, whereas 56% were of the lateral meniscus; in chronic ACL insufficiency, 70% were medial whereas 30% were lateral. Medial collateral ligament Injury Because the medial collateral ligament resists widening of the inside of the knee joint, the ligament is usually injured when the outside of the knee joint is struck. This force causes the outside of the knee to buckle, and the inside to widen. When the MCL is stretched too far, it is susceptible to tearing and injury. This is the injury seen by the action of "clipping" in a football game. An injury to the MCL may occur as an isolated injury, or it may be part of a complex injury