Purpose: Boxer's fracture is one of the most common fractures treated by hand surgeons. In patients who have less than 30 degrees of dorsal angulation and no malrotation, conservative treatment is usually acceptable. Commonly reported complications are non-union, malunion, rotational deformity, and functional deficit. To date, no authors have reported a case of avascular necrosis of the fourth metacarpal head secondary to a Boxer's fracture.

Methods: Two patients who sustained fifth metacarpal fractures are presented. One patient suffered his injury striking a tree, the other patient suffered his injury during volleyball when he struck the ball with a closed fist. Both patients were initially treated with casting followed by early range of motion. Both patients presented at least 6 months after injury with new symptoms of pain in the palm over the area of the adjacent fourth metacarpal head. Radiographs obtained revealed evidence of avascular necrosis of the fourth metacarpal head with complete healing of the previously injured fifth metacarpal. One patient had mechanical symptoms and radiographic appearance of a loose osteochondral flap, he was managed operatively with absorbable pin fixation of the loose fragment. The other patient was observed conservatively with periodic radiographs.

Results: Both patients had clinical resolution of symptoms. Serial radiographs suggest revascularization with evidence of remodeling of the lesions and no further evidence of collapse.

Conclusions: We report the first two cases of avascular necrosis presenting in a delayed fashion in the metacarpal head adjacent to a previously fractured fifth metacarpal. Suspicion should be raised in patients presenting with delayed onset of pain after successful treatment of a fifth metacarpal fracture and appropriate imaging studies should be performed to evaluate the possibility of avascular necrosis.