Metacarpal fracture

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%.

Terminology

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^th metacarpal: reverse Bennett fracture dislocation
• fracture of 5^th metacarpal neck: Boxer fracture

Epidemiology

Fractures of the 5^th metacarpal make up 25% of all metacarpal fractures (which equates to 10% of all hand fractures). 

Pathology

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