Avulsion Fracture in a Skier

A 26-year-old woman presented with acute pain at the base of her thumb after her ski pole hit her hand as she jumped over a small mogul.

The patient's thumb was significantly swollen and markedly weak. It was difficult for her to grasp an object, and she had decreased range of motion.

Radiographs of the thumb showed a small avulsion fracture at the ulnar side of the base of the first proximal phalanx. The fracture was only minimally displaced, and the small fragment was successfully pinned in place using a small Kirschner wire. The patient's hand was placed in a cast.

After 6 weeks, the cast and Kirschner wire were removed. Two weeks later, the patient was asymptomatic, and radiographs showed evidence of healing.

Tears of the ulnar collateral ligament (UCL) of the metacarpophalangeal joint of the thumb are common injuries in skiers, when the ski pole forces the thumb to deviate radially.¹ A torn UCL that is completely disrupted can become displaced superficial to the adductor pollicis aponeurosis (a finding known as the Stener lesion).² The pollicis aponeurosis can become interposed between the metacarpophalangeal joint and the UCL and can interfere with healing of the ligament.

Although splinting is appropriate for stable, undisplaced avulsion fractures and for incomplete ligamentous lesions of the UCL, surgery is required when the ligament has ruptured.¹ Untreated UCL disruptions may have chronic, disabling sequelae. In addition to instability at the first metacarpophalangeal joint, chronic UCL disruption can cause weakness, stiffness, and severe pain. The surgical repair of a chronically disrupted ligament can be significantly more difficult because of proximal folding or retraction of the ligament.

Ligament displacement is sometimes signaled by the presence of an avulsed bone fragment from the medial portion of the proximal first phalanx. This type of avulsion fracture is often accompanied by complete ligamentous disruption. Although MRI may be used to visualize the UCL disruption, the radiographic and clinical findings that demonstrate instability at the first metacarpophalangeal joint are usually sufficient to make an accurate diagnosis of complete ligamentous disruption.

(Case and photographs courtesy of Douglas Beall, MD, of Edmond, Okla, and John Whyte, MD, of Silver Spring, Md.)