Isolated avulsion fracture of the lesser tuberosity of the humerus: report of two cases.

Isolated avulsion fractures of the lesser tuberosity of the humerus are exceptionally rare. Two cases are reported here, each involving a 12-year-old boy. The mechanism of injury appears to be a strong external rotatory force applied while the arm is at maximum external rotation and approximately 60 degrees of abduction. In children and adolescents the fracture most likely occurs through the apophyseal plate of the lesser tuberosity (traction epiphysis). In adults, clinical differentiation from the far more common calcific peritendinitis of the rotator cuff can be difficult. Whereas large, displaced fractures can be easily demonstrated on anteroposterior radiographs with internal and external rotation of the humerus, the axillary view is often necessary to detect smaller fragments with little displacement.