The medial collateral ligament (MCL), also known as the ulnar collateral ligament (UCL), serves to attach the ulna to the humerus and contributes to joint stability. Tears to this ligament most frequently develop as a result of repetitive, forceful throwing motions, so they are typically seen in baseball or lacrosse players. With this condition, you may experience inflammation and pain in the elbow, and lose the ability to exert force into a throw. To treat an MCL tear, your orthopedic specialist may suggest a ligament reconstruction, typically referred to as a Tommy John surgery.