Collateral ligament avulsion fractures from the heads of the metacarpals of the fingers. 
Nineteen patients with collateral ligament avulsion fractures from the metacarpal heads of the fingers were treated during a 6 year period.  Seven undisplaced fractures were initially treated conservatively.  Four united with full movement.  Three required internal fixation for symptomatic non-union and healed without problems.  Eleven patients with displaced fractures were treated by primary internal fixation using a single lag screw through a dorsal approach.  Seven of these achieved a full range of movement of the injured digit by 3 months.  Four patients failed to regain full flexion of the metacarpophalangeal joint.  One patient with a displaced and comminuted fracture was treated with internal fixation at 8 weeks when the fragment had consolidated.  As with similar fractures from the proximal phalangeal bases, these fractures are prone to non-union when treated conservatively, even when undisplaced.  If fixation becomes necessary, the delay of a trial of conservative treatment does not appear to affect the outcome.  Internal fixation of displaced fractures allows gentle mobilisation and facilitates union.