The role of the supinator muscle in the pathophysiological mechanism of a pulled elbow.

A pulled elbow is a common childhood orthopaedic injury that is usually caused by longitudinal traction on the hand. The pathophysiological mechanism of a pulled elbow involves interposition of the annular ligament into the radio-humeral joint. Recent ultrasonographic studies have shown that both the supinator muscle and annular ligament were trapped into the radio-humeral joint. This paper discusses why pulled elbows can occur during pronation and how a pulled elbow can be reduced either by hyperpronation or supination followed by elbow flexion based on the function of the supinator muscle.