Medial Collateral Ligament Injury
The medial collateral ligament (MCL) is one of four ligaments that help stabilise your knee joint. It is located on the inside of your knee joint, and spans from the end of your thigh bone (femur) to the top of your shin bone (tibia).
The MCL is usually injured when the outside of the knee joint is struck. This force causes the outside of the knee to buckle, and the inside to widen. When this happens, your knee can become unstable and easily widen on the inside.
An injury to the medial collateral ligament may occur alone, or it may be part of more serious injury to the knee. Other structures that could also be injured at the same time include include the anterior cruciate ligament (ACL) and the meniscus.