The medial collateral ligament (MCL) connects the femur (thigh bone) and tibia (shin bone) on the inner aspect of the knee. Along with its counterpart on the outer aspect of the knee (lateral [or fibular] collateral ligament) it assures the 'medial-lateral' (i.e. left-right) stability of the knee.

Injuries to the MCL are called sprains (or tears) and they fall into two broad categories : - Simple sprains (Grade I): here the ligament has been slightly stretched and is quite painful. However the knee is not unstable. - Severe sprains (Grade II and III): the knee now 'opens up' when the person walks or when the doctor stresses the knee. The orthopaedist can readily distinguish between the two types on his physical examination. An MCL injury can be associated with other injuries such as a tear of the anterior cruciate ligament, and it is paramount not to miss such injuries.

Severe sprain

Treatment options

Simple sprains : this does not require immobilization of the knee. It can be treated with medications, physical therapy and bracing. The patient can expect a full recovery.

Severe sprains : this mandates the use of at least a sturdy hinged brace and serious physical therapy to prevent lasting stiffness. In the past long leg casts were applied for these conditions, but this approach has been supplanted by the type of brace seen in the illustration. As with simple sprains, a patient can expect a full recovery.

On very rare occasions, surgery can be contemplated to resuture or reconstruct the MCL.