Ulnar collateral ligament disruption is also called skier’s, or gamekeeper’s, thumb. If undiagnosed it leads to chronic instability and weakness of pinch.
Ulnar collateral ligament tears are the result of abduction forces acting on the thumb, putting the ligament under sudden excessive tension.
Avulsion fractures of the ulnar corner of the proximal phalangeal base of the thumb are treated in a fashion similar to the other proximal phalanges. In the thumb however, the avulsed fragment may displace dorsal to the adductor aponeurosis. Options for treatment are lag screw fixation, tension band wiring, or anchor suture for comminuted fractures where the fragments will be excised.