If you snowboard you should definitely wear wrist guards. You don't want to break your hand or wrist and miss out on 6 or 8 weeks of operating.
A prominent ophthalmologist at Utah broke his neck (c6-c7) a few years ago skiing. He's a very experience skier (40+ years doing it). Fortunately, he was able to recover and is operating again, but it's still something you have to consider.
You also have to make sure you don't damage your feet/ankles, or knees. We use the footpetals all the time, and it's a lot harder to do things smoothly if you have to use one foot for both petals (plus just positioning is more difficult if one of your legs is casted/braced).
Dave