My son, at 8, had a broken arm , about 3 yrs ago. We requested a waterproof cast since it was summer - in fact, had to get it replaced on vacation since it got wet - and 2 different ortho offices did not want to put waterproof cast on.
I don't recall the reason why...there was a reason, tho... I just don't remember. So, they are out there, but I guess what I am saying is that it may not always be the best option.
On a side note, the original cast my son had on, he wore to Green Bay Packer "camp" and it was signed by all the Packers - and he was so upset that it had to be cut off. Fortunately, the ortho that cut it off was one of the docs in Green Bay that worked w/ the Packers - doc spent almost 30 minutes cutting off the cast so none of the signatures would be ruined. What a champ! The guy gave up his lunch hour to fit us in and take care of us -
One doctor I like! :chuckle