The Thumb

Abstract

A complete tear of the ulnar collateral ligament of the thumb metacarpal phalangeal joint can be a disabling injury. This injury has been called a “gamekeeper’s thumb.” It has also been called a “skier’s thumb.” However, it can result from any activity or injury that results in hyperabduction of the thumb. It is important to discern whether there is an avulsion fracture associated with the ligament injury and whether or not the rupture is complete. If there is no fracture component to the injury and it is a complete ligament tear, there is a significant chance that the ligament would have avulsed off the base of the proximal phalanx and lies reflected back on itself with the adductor aponeurosis and extensor hood of the thumb interposed between the ligament and its normal area of attachment. This type of pathoanatomy was described by Stener and will not heal if treated nonsurgically (Fig. 8–1). Stress testing in at least 30° of flexion is important to assess whether the disruption is complete. Complete disruption of the ulnar collateral ligament will result in greater than 40° of instability with radially directed stress on the proximal phalanx of the thumb when the MCP joint is in 30° of flexion. Complete disruption of the ulnar collateral ligament is associated with some degree of disruption of the capsule of the MCP joint. If the disruption is determined to be complete and has no avulsion fracture component, the injury should be surgically explored and the ligament repaired.