Rupture of the thumb metatarsophalangeal joint (MCPJ) ulnar collateral ligament (UCL) represents one of the most common ligamentous injuries of the hand. Failure to recognize or appropriately treat these injuries can lead to instability, pain, and weakness of the MCPJ. Ligamentous insufficiency can result from either an acute valgus force on the abducted thumb, as commonly seen in skiing accidents (so-called skier’s thumb), or from chronic repetitive valgus stress (so-called gamekeeper’s thumb).

Early diagnosis is essential because acute treatment can result in improved function and decreased pain. In cases of complete rupture and instability, acute repair provides a more predictable and reliable outcome compared with the treatment of chronic injuries. For patients with chronic UCL injuries, a number of static and dynamic stabilization procedures can be used to treat a non-arthritic joint. For joints in which arthrosis is present, MCP arthrodesis is the recommended treatment for chronic UCL insufficiency.