Skier’s thumb used to be called “gamekeeper’s thumb”. However, the #1 cause of this injury is currently skiing, leading to the name change. Skier’s thumb is an injury to the ulnar collateral ligament of the thumb’s MP joint (the big joint where the thumb attaches to the hand). Skier’s thumb can occur from a fall onto the thumb, especially if the thumb gets bent back by the ground or a ski pole (the #1 cause) or anything else that stresses the ulnar collateral ligament too much.
The ulnar collateral ligament provides thumb stability when pinching or gripping. When the ulnar collateral ligament is injured, pain and weakness, often accompanied by swelling, is experienced when using the thumb.
If the ligament is only partially torn it can heal without surgery. Partial tears of the ulnar collateral ligament are best treated in a short cast for 3 weeks. This is followed by 3 weeks of splinting as needed. If the ligament is completely torn it is best repaired surgically. This is a quick outpatient procedure with a very high success rate. Surgical repair is followed by 3 weeks in a cast followed by 3 weeks of splinting as needed.
Like most injuries when ignored, a complete ulnar collateral ligament tear becomes more difficult to treat after time has passed. This is because over time the torn ligament becomes resorbed by the body, so that it is no longer available to be repaired. The joint subluxes (partially dislocates) because the ligament is no longer stabilizing it, which can lead to arthritis. Treatment of old ulnar collateral ligament tears involves taking a tendon from the forearm (that is not needed) and using it to reconstruct the ulnar collateral ligament that is no longer present. While repair of the natural ligament works better than reconstructing it with a tendon, the tendon reconstruction usually leads to significant improvement in thumb pain and function, although some slight laxity usually persists.
In summary: skier’s thumb is a common ligament injury that can be predictably treated when seen quickly. If neglected, satisfactory treatment options are still available.