There is currently a bloat concerning prosthetic limbs. Now that I've added spines, it might have to be extended along the lines you describe, but I don't think it will delay the first release having a few of these guys around. In part, you'd want to keep them alive because their friends and family will become stricken by grief if they don't make it. Incidentally, relatives and friends also get angry if the body rots while not in a tomb, so you'll want to arrange for the proper arrangements. Also, the number of deaths influences the amount of migration you have. So if the dwarf merchant reports back home that your fortress is a total death trap it would be worse than saying you have some permanent guests in the hospital.
But yeah, according to the current code, they will always seek to be placed in bed and demand food and water, since they consider not being able to walk a "major injury", even if they can't heal. Prior to this system, there were some horrible horrible happenings where dwarves crawled around trying to feed and water themselves, but they'd keep passing out and dropping food. One such dwarf starved to death next to a well because he kept dropping his food to drink and passing out again. It's kind of unfortunately that most of the altruistic behavior has to be explicit in the code.
[ October 03, 2005: Message edited by: Toady One ]