Olecranon fractures exhibit a bimodal distribution: low-energy injuries in the older age group and higher-energy mechanisms in the younger population. The mechanism of injury often dictates the fracture pattern. An indirect injury results from a fall onto an outstretched hand. As the hand touches the ground, a forceful contraction of the triceps muscle pulls a portion of the olecranon off in an avulsion or oblique fashion. This is in contrast to a direct mechanism in which a force is applied directly to the olecranon, leading to a more comminuted fracture pattern. Less commonly, the olecranon may fracture when the elbow is hyperextended, as the bone is impacted against the olecranon fossa of the distal humerus.
1. Bucholz RW, Heckman JD, Court-Brown CM, Tornetta P, Koval KJ. Rockwood and Green's Fractures in Adults: Rockwood, Green, and Wilkins' Fractures, 2 Volume Set. Sixth Edition. Lippincott Williams & Wilkins; 2005