Any reason why the leg can't be amputated and a prosthesis used? I've read about this on elephant feet. Good Year even was involved putting a flipper/tail on a seal. At least you could use him for stud purposes. Not a horse person, just asking.
I have wondered why they don't amputate. Many animals get along just fine.
One Thoroughbred stallion, Spanish Riddle, did have an artificial hoof.
Horses need to be fairly active to remain healthy--the actual damage done to Barbaro's leg is healing as well as could be hoped.
According to Jockey Club rules, all US foals must be the result of "natural cover". That means stallions with relatively functional hind legs.
Actually there was a horse thread about a prosthetic that was used. I didn't save it though.
I am no horse person either, but from what I understand, horses are rather fragile, and if they can't stand up, they have medical problems.