Unusual case of isolated lunate fracture without ligamentous injury.

Fractures of the lunate are rare injuries that usually result from high-energy trauma and are typically associated with other carpal and ligamentous injuries. The incidence of lunate fractures has been cited as 0.5% to 6.5% of all carpal fractures. These fractures are not frequently reported in the literature, and no consensus exists on the treatment of these injuries in the acute and chronic setting. The mechanism typically producing this fracture is a loading force applied to a dorsiflexed, ulnarly deviated wrist such that the capitate is driven downward into the lunate.No prior reports exist in the literature of an isolated fracture of the lunate without perilunate dislocation or ligament disruption. This article reports a case of an isolated displaced transverse shear fracture of the lunate seen 3 months after initial injury, which was successfully treated using a volar and dorsal combined approach and open reduction and internal fixation using microscrews. Bony union across the fracture site was obtained by 7-week follow-up and continued to show improved consolidation through 10-month follow-up. The patient had decreased pain, normal range of motion, and no radiographic evidence of lunate osteonecrosis on most recent follow-up despite the delayed presentation and degree of fracture displacement. This case demonstrates a previously unreported type of wrist injury. Copyright 2011, SLACK Incorporated.