The ulnar collateral ligament of the elbow has three bundles: the anterior bundle (the primary valgus stabiliser), the posterior bundle (a fan-shaped thickening of the posterior capsule, most active beyond 90 degrees of flexion), and the transverse bundle, which runs from olecranon to coronoid and adds little stability. In baseball pitchers the anterior bundle sustains cyclic valgus overload near its tensile limit with every pitch, making UCL reconstruction (Tommy John surgery) one of the most common procedures in professional baseball. Its integrity is essential in the late cocking and acceleration phases of throwing, when valgus stress peaks.
| Origin | Anteroinferior surface of the medial epicondyle of the humerus |
|---|---|
| Insertion | Sublime tubercle on the medial coronoid process (anterior bundle) and medial margin of the olecranon (posterior bundle); the transverse bundle runs between the two on the ulna |
| Actions |
|
|---|
Resists valgus stress at the elbow, with the anterior bundle acting as the primary valgus stabiliser between about 30 and 120 degrees of flexion.
UCL insufficiency in overhead athletes produces medial elbow pain during the late cocking and acceleration phases of throwing and reduced velocity; the milking manoeuvre and moving valgus stress test reproduce the pain. MRI arthrography is the most sensitive imaging study, and the T-sign (contrast tracking along the ulnar attachment beneath the ligament) shows a partial undersurface tear. UCL reconstruction with a palmaris longus or gracilis graft restores valgus stability, with return to throwing at 12 to 18 months and roughly 80-90% of professional pitchers returning to play. Non-throwing athletes with UCL tears can often be managed non-operatively.
Valgus overload injury from overhead throwing producing medial elbow pain at late cocking and acceleration, confirmed by positive moving valgus stress test and MRI arthrography, with surgical reconstruction for athletes wishing to continue overhead sport.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
