Ligament sprains and tears

Knee ligaments are tough bands of fibrous tissue that connect the ends of thigh and leg bones together and provide knee joint stability by limiting excessive movement. There are four knee ligaments. Two on either side of the knee joint, called collateral ligaments, and two within the knee joint, called cruciate ligaments. The collateral ligaments limit side bending and rotation of the knee joint and the cruciate ligaments limit forward and backward shifting of the knee joint. Ligament sprains and tears occur when a force on the knee exceeds the strength of the muscle’s and ligament’s strength.

The ligament on the inner side of the knee, the medial collateral ligament (MCL), is the one most commonly sprained or torn. This occurs with excessive inward bending of the knee. When the injurious force is great enough, other ligaments may be torn, especially the ligament on the inside front of the knee joint, called the anterior cruciate ligament (ACL). This occurs when the side bending force is accompanied by a force that shunts the leg bone forward. An even greater injurious force often leads to damage to a knee disc on the inner side of the knee, called the medial meniscus.

Modifiable contributing and maintaining factors include reduced hip, knee and ankle joint range of movement, and weak and/or shortened buttock, thigh and leg (gluteal, quadriceps, hamstrings and calf) muscles.