# BASE OF 5th METACARPAL

Metacarpal  fractures

Metacarpal fractures are common  Fractures of the base of the metacarpal bones may be the result of direct or indirect trauma.

Metacarpal base fractures

Metacarpal base fracture require reduction if there is greater than 2 mm of articular surface displacement or if there is significant angular deformity or dislocation of the carpometacarpal (CMC) joint. Anesthesia for the reduction is usually accomplished by conscious sedation or regional block, as local hematoma block is usually inadequate. The reduction is accomplished using a combination of traction and direct digital pressure, usually by the physician's thumb. The wrist should be splinted in 20-30° of extension after reduction in order to decrease the deforming pull of the wrist extensors, and the MCP joints should be flexed.

Fractures through the base of the 5th metacarpal require special consideration. These fractures are often intra-articular, with the fracture line between the insertion of the strong intermetacarpal ligaments and the insertion of the extensor carpi ulnaris (ECU) tendon. The pull of the ECU becomes a deforming force, causing the fractured metacarpal to displace proximally and dorsally. This is similar to the Bennett fracture of the thumb ("reverse Bennett fracture"). Fracture management usually requires open reduction and internal fixation (ORIF) or closed reduction and percutaneous pinning. Minimally or nondisplaced fractures should be splinted in the same manner described for other CMC injuries.

Immobilization of reduced metacarpal base fractures or nondisplaced fractures should be continued for a minimum of 3 to 4 weeks. Active motion of the finger IP joints should be encouraged throughout the immobilization period.