A 25 year old rugby player presents with R thumb pain that began yesterday. She reports that she was trying to make a tackle and was stiff-armed. She fell to the ground, landing on an outstretched hand. Her pain is localized to the MCP joint, and she has some swelling and ecchymosis of the thenar eminence. She reports difficulty tying her shoelaces secondary to pain and weakness when she tries to hold the laces.

What injury does she have? How is this injury managed? 

Skier’s thumb, or gamekeeper’s thumb, is an injury to the ulnar collateral ligament (UCL) at the base of the thumb on the ulnar aspect of the MCP joint. The UCL is torn at, or avulsed from, its insertion site at the proximal phalanx of the thumb in 90% of cases.

Skier’s thumb references the acute condition, acquired after a fall or a similar abduction injury to the MCP joint, while gamekeeper’s thumb refers to a chronic condition which develops as a result of repeated episodes of lower-grade hyper-abduction.

On exam, patient will have tenderness at the ulnar aspect of the MCP joint of the thumb. Instability of the MCP joint of the thumb may be noted. Key findings are loss of pinch strength and pain with pinching movement (such as tying shoes and tearing a piece of paper). The patient should be able to abduct the thumb without difficulty.

XRs may demonstrate a bony avulsion fracture from the insertion of the ulnar collateral ligament into the proximal phalanx. Complete rupture of the ligament can be demonstrated by volar subluxation and radial deviation of the proximal phalanx on XR.

Treatment consists of immobilization in the thumb spica splint for four weeks. Some patients will require surgical repair to prevent instability of the joint, chronic pain, and chronic weakness of pinch strength.

June 2024