Metacarpal fractures are common injuries . They account for 30 to 40 percent of all hand fractures. This topic will review issues related to metacarpal head fractures, which are usually the result of direct trauma.
This topic will review issues related to metacarpal head fractures. A general overview of metacarpal fractures is presented separately. (See "Overview of metacarpal fractures".)
Metacarpal heads articulate with their corresponding phalanx. Thus, a fracture of the head is, by definition, an intraarticular fracture. The heads of the metacarpals are bulbous and "cam" shaped, thereby permitting adduction, abduction, flexion, extension and passive rotation of the fingers. The collateral ligaments join the metacarpal to the proximal phalanx and are taut in flexion, while having some laxity in extension (figure 1).
MECHANISM OF INJURY
Fractures of the metacarpal heads are relatively rare and usually result from a direct blow, crush, or missile injury. The second metacarpal (ray of index finger) is most commonly involved, and the first metacarpal head (ray of thumb) is rarely fractured. In some patients, rupture of the collateral ligaments by torsional valgus or varus stress can result in avulsion fractures at the metacarpal head.
SYMPTOMS AND EXAMINATION FINDINGS
Prominent swelling, decreased range of motion, and tenderness is found at the metacarpophalangeal (MCP) joint. Axial load to the MCP joint worsens pain.