I too, think the abnormality was caused by an injury. I read something before that described a buck with a rack similar to that and the antlers actually grew into his head and killed him. What an agonizing death that must have been.
We saw a small buck like that in velvet about 15 years ago. Nobody ever saw him in hunting season though. He either must have survived the season and grown a normal rack the following year or if he was killed, we sure didn't hear about it.