Background

The ulnar collateral ligament (UCL) of the elbow is critical for valgus stability of the elbow and is the primary elbow stabilizer. As such, the UCL plays an important role in most throwing sports, including baseball and javelin, as well as racquet sports and ice hockey.

Elbow injuries in young athletes are generally chronic, with persistent pain and instability from repetitive overhead activities. In the athlete, ligamentous injury can also be heralded by an acute traumatic event such as an elbow dislocation. This can then lead to chronic pain and valgus instability. An understanding of the anatomy and biomechanics of the elbow in throwing sports is essential to the correct diagnosis and treatment of this potentially disabling injury.

Functional Anatomy

The UCL originates at the posterior distal aspect of the medial epicondyle and inserts into the base of the coronoid process. At 90 º of flexion, it provides 55% of the resistance to valgus stress at the elbow. In full extension, the UCL, bony architecture, and anterior capsule equally maintain valgus stability.

The UCL is composed of 3 bands: anterior, posterior, and transverse. The anterior band, which arises from the anteroinferior surface of the medial epicondyle and inserts on the sublime tubercle of the ulna, provides the major contribution to valgus stability.

History

• Medial elbow pain is the most common symptom in athletes who throw. Pain may be especially prominent during the acceleration phase of the overhead throw.
• Pain is often chronic or recurrent, and it may lead to a slow erosion of the patient's throwing ability.
• Athletes may report having had similar pain in previous seasons of throwing.
• Rest generally helps to relieve the pain.
• Occasionally, during a single throw, athletes may experience acute pain over the medial elbow, sometimes associated with a popping sensation, that causes them to immediately stop throwing.