Injury pattern for traumatic elbow dislocation described by O’Driscoll et al. A, Three stages of elbow instability from subluxation to dislocation: stage 1, disruption of the ulnar part of the lateral collateral ligament; stage 2, disruption of the other lateral ligamentous structures and posterior capsule; stage 3A, partial disruption of the medial ulnar collateral ligament and posterior medial ulnar collateral ligament only; and stage 3B, complete disruption of the medial ulnar collateral ligament and posterior medial ulnar collateral ligament. B, Soft-tissue injury progresses in a circle from lateral to medial correlating with those shown in A. LUCL, lateral ulnar collateral ligament; MUCL, medial ulnar collateral ligament; PLRI, posterolateral rotatory instability