I don't personally have any exerience with a broken limb but a friend of mine has a poodle who broke both front legs. The were outside and he jumped up to be with her but there was no "shelf" where he jumped up to, it was just a fence and he wound up landing on his front paws and broke both. She said that they were clean breaks so it was easy to set and he would not have problems with artrithis. He was casted for 6 weeks.
But is he all better now.
Good luck with your baby. Hopefully he will not need surgery.