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.
Review Date 4/21/2019
Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.