Définition

The medial collateral ligament (MCL) is a supporting structure on the medial part of the knee joint. View image Its primary function is to resist valgus (twisting outwards away from the mid-line) and external rotation forces of the tibia in relation to the femur. The mechanism for MCL injury is typically a large valgus and/or external rotation force that is suddenly placed on the knee joint. Injuries to the MCL range in severity from a few torn fibres to complete disunity of the ligament.