What typically causes gamekeeper's thumb?

Gamekeeper's thumb is typically caused by forceful abduction and hyperextension of the thumb, resulting in an injury to the ulnar collateral ligament (UCL) at the MCP joint. This type of injury is often seen in individuals who engage in activities that put strain on the thumb, such as skiing or certain sports where the thumb may be excessively pulled or pushed outward when the hand is in an awkward position.

Injuries from direct trauma to the fingertip usually result in different types of damage, such as fractures or lacerations, rather than affecting the ligament as seen in gamekeeper's thumb. Repetitive strain on the wrist does not specifically lead to the acute UCL injury but may contribute to other conditions like tendonitis. Lastly, the rupture of the A1 pulley is associated with trigger finger and does not directly relate to the mechanisms involved in gamekeeper's thumb, which specifically concerns the UCL. Understanding the mechanics of the injury is crucial for both diagnosis and treatment.