Metacarpophalangeal Sprain of the Thumb in Downhill Skiers: Ergonomic Study

Sprain of the thumb metacarpophalangeal (MCP) joint is a frequent and serious injury in downhill skiers. A prospective study of 119 cases during the 1984-1985 winter season was carried out to determine the sprain mechanism and its correlation with the skier's ability, the type of ski pole, and the injury. Four basic mechanisms were found to be involved. 1. Thumb dislocation by the strap when the skier's hand slid down the pole. 2. Impact of the abducted, antepulsed, and extended thumb in the snow, the hand moving forward, seen when the hand was ejected from the upper end of the pole. The design of the pole handle and the way it was gripped gave the hand a dangerous position with the thumb out stretched perpendicular to the palm. The injury would result from the thumb being stopped by the snow and the hand sliding forward. 3. In some falls, the hand rotated around the insertion of the strap, giving a contusion of the ulnar aspect of the MCP joint. 4. The thumb end could get caught in the snow when the falling skier tried to recover his balance with hand closed on the pole handle. It was concluded that: (1) the pole strap was a risk factor of unequal importance in competitors and the others, (2) “safety clips” were inefficient, (3) pole handles that surround the hand were dangerous, (4) during the fall the hand must be prevented from being ejected with the thumb abducted, and (5) some parts of existing pole handles were dangerous. The characteristics of an ergonomic downhill ski pole handle are suggested. The corresponding prototype is demonstrated.