Skier's (Gamekeeper's) thumb

Skier's thumb is an acute injury to the ulnar collateral ligament (UCL) of the thumb MCP joint, classically occurring when a ski pole forces the thumb into radial deviation on a fall. Gamekeeper's thumb refers to the chronic attritional form historically seen in game wardens. The UCL stabilizes the thumb against lateral stress during pinching and gripping — when it tears completely, the joint becomes unstable and pinch strength is severely reduced.

A Stener lesion occurs when the avulsed ligament end is displaced outside the adductor aponeurosis, preventing spontaneous healing — this is the key reason many complete tears require surgery.

Radial stress testing of the MCP joint in 30° of flexion reveals laxity. Valgus opening >35° or >15° greater than the opposite side indicates complete rupture. Stress X-rays confirm and MRI can identify a Stener lesion before surgery.

Complete UCL tears and all Stener lesions require surgical repair. A Stener lesion cannot heal on its own.

External patient-education references and related OSI pages for additional background:

• Britannica — Hand (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language