Bennett's fracture

Common fractures to the thumb metacarpal include Bennett's fracture and Rolando's fracture.

The Rolando fracture is less common than the Bennett's fracture, and is associated with a worse prognosis.

Bennett's fracture is a fracture of the base of the first metacarpal bone which extends into the carpometacarpal (CMC) joint.

The Bennett's fracture is an oblique intraarticular metacarpal fracture dislocation, caused by an axial force directed against the partially flexed metacarpal.

Symptoms of Bennett's fracture are instability of the CMC joint of the thumb, accompanied by pain and weakness of the pinch grasp.

For Bennett's fractures where there is more than 3 mm of displacement at the trapeziometacarpal joint, open reduction and internal fixation (ORIF) is typically recommended.

Therefore, the goal of treatment of Bennett's fracture should be to achieve the most precise reduction possible, whether by the CRPP or the ORIF approach.

In the most minor cases of Bennett's fracture, there may be only small avulsion fractures, relatively little joint instability, and minimal subluxation of the CMC joint (less than 1 mm).

Because of the aforementioned biomechanical features, Bennett's fractures nearly always require some form of intervention to ensure healing in the correct anatomical position and restoration of proper function of the thumb CMC joint.

In the case of the Bennett's fracture, the proximal metacarpal fragment remains attached to the anterior oblique ligament, which in turn is attached to the tubercle of the trapezium bone of the CMC joint.

For Bennett's fractures where there is between 1 mm and 3 mm of displacement at the trapeziometacarpal joint, closed reduction and percutaneous pin fixation (CRPP) with Kirschner wires is often sufficient to ensure a satisfactory functional outcome.

With this in mind, failure to properly recognize and treat the Bennett's fracture will not only result in an unstable, painful, arthritic CMC joint with diminished range of motion: it will also result in a hand with greatly diminished overall function.