Isolated Avulsion Fracture of the Lesser Tuberosity of the Humerus

An extremely rare isolated avulsion fracture of the lesser tuberosity, not complicated with other proximal humeral fractures or posterior shoulder dislocations, occurred in a 12-year-old girl. The avulsion fracture of the upper part of the lesser tuberosity appears to have been caused by hyperextension and hyperexternal rotation of the shoulder. In this position, the coracohumeral ligament, superior glenohumeral ligament, and subscapularis tendon could have pulled out the upper part of the lesser tuberosity. She gained full recovery of left shoulder function after three months of conservative treatment, although follow-up roentgenograms show nonunion of the fracture. An isolated avulsion fracture of the lesser tuberosity is extremely rare. Only 12 cases, none in children, have been found in the literature since Hartigan's report in 1895.