Ok, I understand all the "technical" stuff, but anyway, Hershel was bitten and had half of his leg amputated by complete amateur surgeons and there he was, runnig happily across the fields until he got his neck amputated by the Governor and that was, yes, the ultimate amputation. I'm not sure if implementing amputation would be fun or not, but I think that if we stick too tight to realism then maybe we shouldn't play a game which is about... well... surviving a zombie apocalypse.