Ulnar collateral ligament rupture of the first metacarpophalangeal joint: a frequently missed injury in the emergency department.

Between July 1991 and December 1995, 28 patients elected to consult one of the senior authors for a second opinion or were referred to him by their family physician after being reassured and discharged from our emergency department with the simple diagnosis of "soft tissue contusion" to the thumb. Physical examination and stress radiographs of these patients revealed a missed injury to the ulnar collateral ligament (UCL) of the first metacarpophalangeal joint in 18 patients (64.3%), 12 of whom required surgical repair. Apparently, UCL injuries are frequently underestimated in our emergency department, although the real number is unknown because some patients may have decided to seek further treatment elsewhere. In addition to the numerous trivial injuries that are frequently seen in any emergency department, emergency physicians have the added responsibility of detecting those injuries that require referral to a specialist.