Diagnosis by ultrasound of dislocated ulnar collateral ligament of the thumb.

The ability of ultrasound to assess a displaced ulnar collateral ligament of the 1st metacarpo-phalangeal (MCP) joint was evaluated. If the ligament is ruptured and displaced proximal to the adductor aponeurosis, a surgical repair should be undertaken to restore stability. Ultrasound accurately diagnosed these lesions in 32/39 operated patients. In 4 cases the ultrasound examination suggested a more severe lesion than was found at operation. In 3 cases a lesser injury was suspected than later proved to be present.