The problem with any advanced medical system’s addition to Unturned is that the negative effects can easily be negated by committing suicide, albeit at the cost of skills.
Solution (my solution): make skills more important and/or remove crafting recipes which the player has learned upon their death (not implying it’s a confirmed feature), of course they could learn them again later but that takes time.
Annoying, sure. But it deters more seasoned players from picking the easy way.
If you’re going to allow players to be able to lose certain limbs: there should probably be a way to get them back beyond suicide.
The simple solution is just prosthetics, this would undoubtedly have downsides. Knowing Unturned’s PvP: people are going to be full of prosthetics if they’ve survived a longer amount of time.
However if you would like the affect on the player to be able to be entirely negated: this would probably involve taking even further a step into the Sci-fi direction with the Scorpion-7 stuff, this being robotic limbs or grown limbs (one of which might give an advantage so probably not that).
The idea and underlying principles of this suggestion do resemble similarities to another reply I had made to a similar thread on the matter, so I’ll just throw this here.