The medial collateral ligament of the elbow (UCL) consists of three bundles: the anterior band (strongest, primary valgus stabiliser at 30-120 degrees of elbow flexion), the posterior band (active at greater than 90 degrees flexion), and the transverse band (minor). The anterior band is the primary structure injured in throwing athletes from repetitive valgus loading, producing the chronic medial elbow pain and instability of UCL insufficiency.
| Origin | Medial epicondyle of the humerus |
|---|---|
| Insertion | Sublime tubercle of the ulnar coronoid (anterior band) and olecranon (posterior band) |
| Actions | Primary elbow valgus stabiliser; resists the valgus forces of throwing and heavy lifting |
|---|
UCL reconstruction (Tommy John surgery) uses a palmaris longus, gracilis, or ipsilateral long toe extensor graft to reconstruct the anterior bundle through bone tunnels in the medial epicondyle and coronoid (docking or figure-of-8 techniques). Return to throwing sport takes 12-18 months. Acute complete UCL tears in non-throwing athletes can be managed non-operatively.
Anterior bundle MCL degeneration in overhead throwing athletes producing valgus elbow instability managed with UCL reconstruction (Tommy John surgery).
