A torn (MCL), is an injury to the medial collateral ligament. This ligament extends from the upper-inside surface of the tibia to the bottom-inside surface of the femur. The ligament prevents the knee joint from medial instability, that is, instability in the inside of the joint.
Linda J. Vorvick, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.