The Ulnar Collateral Ligament (UCL) is the ligament on the inside or medial aspect of the elbow that provides stability against forces that stress that part of the elbow, such as throwing. The UCL is made up of three components; the anterior band, posterior band, and transverse band. The anterior band is the most important and is the main stabilizer. This ligament is most commonly injured with throwing a baseball or javelin and with elbow dislocations.
Injury to the UCL may occur acutely with a single event or gradually over time. Over time overuse, minor injuries and bad pitching mechanics can lead to stretching out of the ligament and eventual failure. When this occurs, one cannot continue to pitch without pain and there is a loss of velocity and control.
If there is an acute injury to the UCL or a chronic one that affects one’s ability to throw, it should be evaluated by a sports medicine specialist familiar with throwing injuries. Many of these injuries are not diagnosed accurately or there may be a delay in making the correct diagnosis and treating the injury appropriately if a specialist is not seen.