Awe... that poor little guy! Did the vet say that it may be a genetic thing? It sounds as though it may be something like that, and not just an injury.

Can you talk to a specialty vet hospital in your area and see if they can give a more precise diagnosis? We have Univ. of Penn here in eastern PA. Not sure what is in your area. They are sooooo good with the animals when they have these out of the ordinary kind of problems.

I wish you luck, and hope that Max will be ok. Give him some hugs and kisses from me.