Gamekeeper's Thumb

Excerpt

The metacarpophalangeal (MCP) joint of the thumb plays an important role in normal hand gripping and pinching. The radial and ulnar collateral ligaments (UCL) are the primary stabilizers to varus and valgus stress on this joint. From the functional point of view, the UCL is of greater importance because it resists radially directed forces during forceful grasping. The term “gamekeeper’s thumb” was first coined in 1955 by Campbell who identified the UCL injuries as an occupational disease in Scottish gamekeepers. The gamekeepers sacrificed the rabbit by strangling the animals with their thumb and index finger, and the repeated valgus stresses resulted in UCL injury and chronic instability of the MCP joint. In the present day, this lesion occurs more frequently in acute sports-related injuries.

The UCL is composed of a proper collateral ligament (PCL) and an accessory collateral ligament (ACL). The PCL originates from the dorsal third of the metacarpal head and inserts on the volar aspect of the proximal phalanx. The ACL originates palmar to the PCL and runs continuously with the PCL to insert on the volar plate. The PCL is taut in flexion, while the ACL is taut in extension. Both ligaments ensure the ulnar stability of the MCP joint. The Adductor pollicis inserts on the proximal phalanx, functioning as a dynamic stabilizer of the MCP joint. It lies superficial to the UCL. Understanding the structural relationship between the adductor pollicis aponeurosis and the UCL is crucial to understand the pathoanatomy of the "Stener lesion."