A medial meniscus tear is an injury characterized by tearing of cartilage tissue located at the inner aspect of the knee and typically causes pain in this region. The knee joint comprises of the union of two bones: the long bone of the thigh (femur) and the shin bone (tibia). Between the bone ends are 2 round discs made of cartilage called the medial (inner) and lateral (outer) meniscus. Injuries to the medial meniscus are more common than lateral meniscus injuries. Occasionally a medial meniscus tear may occur in combination with injuries to other structures of the knee, such as the cruciate ligaments, the collateral ligaments, or the lateral meniscus.