Two prime examples of terrifying thumb injuries come to mind, both involving what is called gamekeepers thumb.
Gamekeepers thumb (skiers thumb) got its name from the “gamekeepers” of old, basically popping necks of rabbits, chickens, ducks, platypus, rhinoceros, and basically any poppable animal. The ulnar collateral ligament connects to the base of the thumb, from another bone in the back of your hand. It prevents your thumb from touching your wrist, a rather painful complication. I personally have been on the receiving end of this injury twice. One time while tacking in football, the other while training for AK in the local Midwest ex-dump converted to ski… well hill I guess you say. Both times are examples of acute injury, when a single incident causes gamekeepers thumb, basically by making your thumb touch the wrist. Painful and it typically doesn’t just tear the ligament (bad enough) but brings some bone with it. Treatment depends on severity and your doctor’s decision. This is also an injury when you do go to the doctor; it’s your opposable thumb we’re talking about!
So why should you, the skier or climber, be wary of a condition named for professional head-popper-offers? When you catch yourself after a crash in skiing, and you didn’t put your poles on properly (I was guilty of that), it puts your thumbs in direct contact with the ground. When bouldering, many spot with their thumbs parallel to the ground, rather than thumbs up. Huge mistake. One of the first things offensive lineman are taught in football is thumbs up. This prevents thumb injuries, as you’re less likely to push your thumb into your wrist. Same thing with bouldering, keep your thumbs up!
So remember, wear your poles correctly, hands go from the bottom of the wrist loop up, this puts all the weight on your wrist while pole planting, preventing hand fatigue. Also, when spotting your partner while bouldering, thumbs always point up, not inwards or down.