I wonder what their reasoning is? Are they saying that artificial joints can't stand up to the added weight or is it that fatties don't deserve them because they brought joint deterioration on by themselves?
I don't know the answer, but I wonder if it's just an exercise in futility. Since as far as I know, artificial joints aren't in limited supply (like donated organs), I would see no reason to refuse, unless there is some other limit, such as doctor shortage, hospital bed shortage, etc.
If there is a limiting factor, then I would make a value judgement and deny those with self-inflicted problems.
If they're denying them replacement because it's self-inflicted that's stupid. If those poeple have any hope of LOSING the weight it's better diet and excercise. Denying them the ability to move would be like refusing to give people trying to quit smoking nicotine patches. This MUST be a government operation.