Located along the knee joint, the medial collateral ligament (MCL) is a flat band of connective tissue that connects the femur bone in the thigh to the tibia bone in the lower leg and helps to support the knee joint. It is also known as the tibial collateral ligament. As the MCL runs vertically along the inside of the knee, it specifically stabilizes the joint against forces that would push the knee inward.
This inner knee ligament is accompanied by the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and lateral or fibular collateral ligament (LCL). The ligament also is accompanied by bands of fibrous tissue that connect the upper and lower leg bones. These accompanying tissues help maintain the structure of the knee joint.
The top, or proximal, end of the medial collateral ligament attaches to the femur bone just below a point on the inside edge of the bone known as the adductor tubercle. This is also approximately where the adductor magnus, a large inner-thigh muscle, inserts above the knee. From there, the MCL descends several inches, where the bottom or distal end attaches to a portion of the tibia known as the medial condyle, which is a surface found on the top inside edge of the tibia bone. Also located at this point is the per anserinus, a convergence of the tendons of three inner-thigh muscles — the sartorius, gracilis, and semitendinosus — that cross the knee joint and insert at the tibia superficially to the distal end of the medial collateral ligament.
Commonly injured in sports such as football and downhill skiing, the MCL is susceptible to lateral blows and other forces that drive the knee excessively inward. When this occurs, the ligament can be stretched to the point of a sprain or even torn. Depending upon the degree of damage, recovery can take weeks or months, and recommended treatment can vary accordingly. In the case of mild sprains, resting and icing the joint is the suggested therapy. Over-the-counter anti-inflammatory drugs may also be advised, as reducing inflammation and swelling to the injured ligament is the goal of treatment.
If, on the other hand, a more severe injury to the medial collateral ligament is sustained, arthroscopic surgery may be required to repair the damage. Most moderate injuries to the MCL alone can be treated without surgery. An injury severe enough to tear the MCL is often accompanied by damage to other knee ligaments, such as the ACL. Surgery to address multiple ligament injuries can take months of healing time, followed by rehabilitation and long-term conditioning to maintain joint integrity and lessen the risk of re-injuring the area.