Metacarpal fractures are common. Fractures of the metacarpal bones account for 10% of all fractures and 40% of all hand fractures. The lifetime incidence of a metacarpal fracture is 2.5%.
Specific names are given to fractures of the base of the first metacarpal (see: fractures of the thumb):
- Bennett fracture dislocation
- Rolando fracture
- epibasal thumb fracture
- gamekeeper thumb (not always includes a fracture)
Specific names are given to fractures of the fifth metacarpal:
- fracture dislocation of the base of the 5 metacarpal: reverse Bennett fracture dislocation
- fracture of 5 metacarpal neck: Boxer fracture
Fractures of the 5metacarpal make up 25% of all metacarpal fractures (which equates to 10% of all hand fractures).
They are a result of direct or indirect trauma with the nature and direction of the force being directly related to the type of injury. Specific injury patterns include:
- carpometacarpal (CMC) joint injury
- metacarpal base fractures and dislocation of the CMC joint
- metacarpal shaft and neck fractures
- these are usually a result of axial loading or direct trauma (clenched fist and solid surface); torsional force may also result in this type of injury
- metacarpal head injury
- these are intra-articular fractures that result from axial loading or direct trauma; collateral ligament avulsion fractures are caused by forced deviation of the flexed metacarpophalangeal joint (MCPJ).
- metacarpophalangeal joint dislocations
- dorsal MCPJ dislocations are the most frequent and a result of forced hyperextension of the digit