The ulnar collateral ligament (UCL) 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 joint. It is sometimes also referred to as the medial collateral ligament (MCL) of the elbow (not be confused with the MCL of the knee.)
The UCL attaches the ulna bone (which, along with the radius, is one of the two bones of the lower arm) to the humerus bone of the upper arm. It connects these bones on the medial (inner) side of the arm.
In most people, injuries to the elbow UCL are rarely caused by stress inflicted on the joint during a throwing motion. But for athletes such as baseball pitchers, javelin throwers or lacrosse players, the forceful repetitive motion of their sport can cause inflammation (swelling), cartilage injuries, bone spurs or even a tear in the ligament.
When the elbow UCL is torn, a person will still have a full range of motion in the elbow, as well the ability to throw. However, he or she will not be able to exert significant force into a throw. Elbow UCL tears are often the result of a gradual process of "attenuation" (weakening) of the ligament. In some cases, it may not be immediately clear that the ligament has been torn, but some people report hearing a pop at the time of injury.
Ulnar collateral ligament reconstruction, commonly known as Tommy John surgery, is a highly successful treatment for elbow UCL tears. Get more detailed information on elbow UCL tears and Tommy John surgery in the articles and other content below.