The lateral collateral ligament (LCL) is one of the four knee ligaments. It spans the distance from the end of the femur (thigh bone) to the top of the fibula (thin, outer, lower leg bone) and is on the outside of the knee. The lateral collateral ligament resists widening of the outside of the joint. A lateral collateral ligament injury happens from a direct force from the side of the knee, causing moderate to severe knee pain and ligament injury which often leads to knee surgery. It is much less frequent ligament injury than the medial collateral ligament (MCL) but commonly occurs with other ligament injury to the knee.





