The medial collateral ligament (MCL) refers to one of four ligaments which are critical in order to provide the stability of the knee joint. This is a ligament which is made of tough fibrous material. It functions in order to control excessive motion by limiting the mobility of the joint.
The medial collateral ligament spans the complete distance from the end of the thigh bone to the top of the shin bone. It is on the inside of the knee joint. It helps to resist the widening of the inside of the knee joint.
Since the medial collateral ligament tends to resist the widening of the inside of the knee joint, it usually gets injured when the outside of the knee joint gets struck. This tends to cause the outside of the knee to buckle, which makes the inside widen. When this medial collateral ligament gets stretched too far, it becomes susceptible to tearing as well as injury.
An injury in such as way may occur as an isolated injury, or it may even be a part of a complex injury to the knee. Other ligaments, usually the anterior cruciate ligament, or the meniscus (cartilage), may also be torn along with the medial collateral ligament injury.
The most common symptoms following such a ligament injury is pain which is directly over the ligament. Swelling over this torn ligament may appear, besides bruising as well as generalized joint swelling is common. In more severe injuries, patients may complain that the knee is unstable, or feel as though the knee may buckle. Symptoms of such ligament injury tend to correlate with the extent of the injury. MCL injuries are graded on a scale ranging from I to III.
Grade I MCL Tear refers to an incomplete tear of the MCL. In this case, the tendon is still in continuity, and the symptoms are minimal.