(A) A direct force applied to the posterior aspect of the elbow causes the sharp articular margin of the olecranon to wedge the medial condyle from the distal humerus.
(B) Falling on the outstretched arm with the elbow extended and the wrist dorsiflexed causes the medial condyle to be avulsed by both ligamentous and muscular forces.
Reproduced with permission from: Beaty JH, Kasser JR. The elbow: Physeal fractures, apophyseal injuries of the distal humerus, avascular necrosis of the trochlea, and T-condylar fractures. In: Rockwood and Wilkins' Fractures in Children, 5th ed, Beaty JH, Kasser JR (Eds), Lippincott Williams & Wilkins 2001. Copyright © 2001 Lippincott Williams & Wilkins.
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