The posterior bundle of the elbow MCL fans out from the medial epicondyle to the olecranon, providing supplementary medial stability particularly in the flexed position. It is less important than the anterior bundle for valgus restraint but contributes to posteromedial elbow stability with the olecranon and the posteromedial joint capsule.
| Origin | Posterior inferior medial epicondyle |
|---|---|
| Insertion | Medial olecranon border |
| Actions | Taut in elbow flexion; contributes to postereomedial elbow stability; the posterior band of the MCL complex |
|---|
Posteromedial elbow impingement from valgus extension overload in overhead athletes involves the posterior MCL bundle, medial olecranon, and olecranon fossa osteophytes. The moving valgus stress test provokes posteromedial pain from 120-70 degrees of flexion. Arthroscopic debridement of posteromedial osteophytes combined with UCL reconstruction (if unstable) addresses this combined pathology.
Valgus extension overload producing medial olecranon and posterior bundle stress fractures and osteophytes in throwers managed with arthroscopic debridement.
