[Noah930]

A lot depends on where the fracture is located, and if there's any displacement (movement from natural alignment) of the bones. (Fracture = break in medical terms. Same difference.) If the fracture extends into one of the joints (sounds like it's close to the metacarpophalangeal--MP--joint, from your description), then you may even want to consider surgery to pin it temporarily. If you've been told that no surgery is necessary, then your son will be stuck in some sort of orthopedic device for about 4-6 weeks. Even with surgery, your it'll still take 4-6 weeks for the fracture to heal, during which time it'll have to be splinted/casted.

If there's no real displacement (so that the edges of bone still line up together), but there is some angulation (which will most likely be palmar, meaning the distal/far end of the bone out to the fingertip angles down abnormally to the palm side of the digit when you're viewing the lateral/sideways x-ray), then that's fairly well tolerated. Even if there's up to about 30 degrees of palmar angulation, it's usually acceptable, as the thumb will learn to adapt and there won't be much loss of function. Fractures that go into the joint, or result in rotation/twisting of the bone usually need surgery, though.

If the plaster/fiberglass splint is too big and bulky to be tolerated, there are lower profile alternatives. An occupational or hand therapist can easily make a custom-fitted thumb spica splint out of thermoplastic. There are off-the-shelf short-arm thumb spica splints made out of textile (with a metal support) that you can buy. They look like what a supermarket checker would wear, and extend up to the forearm. Might be a bit bulky to fit under a ski glove. There's also a company that makes smaller hand-based thumb spica splints out of textile/leather/metal. I'll have to go to the office to look up that company's contact info, as it's a little mom 'n pop mail order outfit from Odessa, TX, IIRC.

In general, the bulkier the support (like a cast), the better the protection. So a cast will protect better than a splint. A fiberglass/plaster splint will protect better than thermoplastic, which will be better than the off-the-shelf removable thingies.

Personal opinion: Obviously, I haven't seen the x-rays, but in general, I usually would recommend that a kid sit out and wait for an injury to heal reasonably before getting back into the sport. That's 4 weeks for something like a phalangeal fracture in a kid. Be better to miss 4 weeks of skiing, than fall again and really F-up the thumb and convert a non-surgical treatment into a surgical one. If your son's a freshman, he's got 3 more years to compete at this level. If he's not going to go to the Olympics or turn pro, then 10-20 years down the road it shouldn't matter if he missed one month/season. If he really is going to compete for a gold medal some day, then, again, he's already got the natural talent to have plenty of other opportunities in his ski career to be a hero. Just IMO.

Post pics of the fracture, if you've got 'em.

edit: The company that makes the hand-based (as opposed to short arm-based) thumb spica splint is called Arthritic CMC Thumb Brace Co. The splint is about $30. Phone # (888) 499-4123. It's not nearly as supportive as a real cast (which is the proper way to treat this type of injury, with or without surgery), but it'll fit under a ski glove.