Why is an injured thumb called a skiers thumb?

Injury thumb: Thisis a common injury that skiers get. It occurs from a fall on an outstretched thumb that hyperextends at the mcp joint. Chronically if not treated laxity develops and repeat injury and pain is common. Unfortunatel skiers fall and get this injury commonly. It is also called gamekeepers thumb from keepers of game birds whosre job it was to break the birds neck. http://www.handctr.com/thumb-sprain.

Mechanism of injury: Classic way to injury a thumb ligament is thumb vs ski pole.