The medial collateral ligament (MCL) of the elbow of is part of the complex of ligaments and tendons that attach and stabilize the bones of the lower and upper arm where they meet at the elbow. Specifically, the MCL attaches the ulna – which, together with the radius, make up the bones of the lower arm – with the humerus, the bone in the upper arm.
When the MCL of the elbow is torn, the individual retains full range of motion in the joint and the ability to throw, but cannot exert significant force. MCL tears are often the result of a gradual process of attenuation (weakening). It may not be immediately obvious that a person has torn this ligament, although some people report hearing a pop at the time of injury.
Fortunately, surgical treatment of MCL tears often yields excellent results. Known by baseball fans everywhere as the "Tommy John surgery" – this treatment involves a procedure in which a tendon is taken from another part of the body and acts as a replacement for the injured ligament. Today, through efforts in research and innovation, orthopedic surgeons at Hospital for Special Surgery have fine-tuned the procedure and are now able to use a safer muscle-splitting technique that minimizes trauma to the muscles.