Imaging description

The radiographs show a comminuted spinal fracture in the distal half of the humerus with a butterfly fragment (Figure 17.1). The butterfly fragment is typically seen medially. No underlying lesion is seen to suggest a pathological fracture.

Importance

Distal humerus fracture can be caused by severe muscular pulling from throwing action without direct trauma and is called ball-thrower’s fracture. Because the lack of history of trauma may prompt the search for underlying pathology, knowledge of this entity is important to preclude unnecessary imaging studies or biopsy.

Typical clinical scenario

Ball-thrower’s fractures commonly affect recreational athletes who are involved in throwing actions. The average age of patients was 25 and 36 years from two large series. It can occur in teenagers and rarely affects professional players. The majority of the patients are male. The patient is trying to perform a hard throw, during which a closed, external rotation spiral fracture occurs in the distal humerus. The sound of the fracture may be heard by the patient and/or others. The fracture is considered to occur during the acceleration phase before ball release. The throwing objects vary and include a stone, snowball, handball, softball, baseball, and hand grenade. Ballthrower’s fracture has uneventful prognosis with conservative treatment with a hanging cast for 6–8 weeks.

Differential diagnosis

Little League shoulder (physeal stress fracture), medial epicondyle injury, and stress fracture of the proximal ulna may be suspected clinically as sports-related injuries. Radiographic study is diagnostic for ball-thrower’s fracture. MRI may be helpful for subtle physeal stress fractures, stress fractures, and medial epicondyle injuries.