Snapping annular ligament of the elbow joint in the throwing arms of young brothers.

We examined young brothers with symptomatic snapping elbow in the throwing arm. Arthroscopic examination confirmed the mechanism of snapping, in which loose and protruded annular ligament-like tissue covered the volar half of the radial head in elbow extension and uncovered the radial head in deep elbow flexion. Arthroscopic resection of the annular ligament-like tissue was performed in one brother. Histologic examination of the removed tissue showed degenerated ligament tissue. Excision of loose annular ligament abolished snapping. Contralateral elbows of the brothers also showed similar asymptomatic snapping. Researchers suggest that a hereditary factor contributing to loose annular ligament and repetitive microtrauma from throwing is the cause of symptoms.