Metacarpal fracture is a kind of bone fracture palm which can be divided into several categories:
1. The fracture of the first metacarpal base: 1cm at the base of the first metacarpal fracture, mostly transverse or comminuted fracture, causing indirect violence. Shift direction is to the radial projection dorsal angulation.
2. The fracture of the bottom of first metacarpal base and dislocation (Bennett fracture): caused by indirect violence, displacement direction inside the base of the first metacarpal bone triangle remain in place, while the fracture distal articular surface of the trapezium to the dorsal and radial dislocation.
3. Metacarpal neck fracture: caused by direct violence and indirect violence. It is most common in the fifth metacarpal. Shift direction is the projection into the dorsal horn (interosseous muscle stretch and lumbrical). Because of the back extensor tendon stretch, the proximal phalanx dorsal dislocates of the metacarpophalangeal joint hyperextension.
4. Metacarpal shaft fracture: direct violence, for single or multiple fractures, mostly transverse or comminuted fracture; twisting or convey cause violence, mostly oblique or spiral fractures. Shift direction is into the dorsal horn and lateral displacement, because interosseous muscle and flexor muscle pull.