Boxer Fracture (Fifth Metacarpal Neck)

Boxer fracture (also called brawler fracture or street fighter fracture) is a metaphyseal fracture of the neck of the fifth metacarpal bone, named for the typical mechanism of striking an object with a closed fist. The fracture is classically transverse or short oblique with volar angulation of the metacarpal head because of the pull of the intrinsic interosseous muscles and lumbricals. The fifth ray's inherent mobility (20-30 degrees of flexion at the carpometacarpal joint) tolerates more angulation than other rays.

Patients present with pain, swelling, and ecchymosis over the dorsoulnar hand, loss of the fifth knuckle prominence (depressed metacarpal head), and pain on grip. Critical examination assesses rotational deformity by asking the patient to make a fist and observing whether all fingertips converge toward the scaphoid; rotational malalignment of even a few degrees impairs hand function and is more important than angulation. Open wounds over the MCP joint after a punch may represent fight bite injuries with high infection risk.

Treatment depends on angulation, rotation, and skin status. Acceptable angulation is up to 40-45 degrees in the fifth metacarpal (more than 30 degrees may benefit from reduction). Closed reduction with the Jahss maneuver (90-90 method) followed by ulnar gutter splint with MCP at 70-90 degrees flexion and PIP/DIP at 0-20 degrees flexion for 3-4 weeks is standard. Surgical fixation (closed reduction percutaneous pinning, plate-screw fixation, or intramedullary pinning) is indicated for severe angulation >40-45 degrees, any rotational deformity, multiple metacarpal fractures, open fractures, or fight bite contamination. Hand therapy promotes recovery of grip and motion.