When under the effects of Advanced Radiation Poisoning (400+ Rads) any crippled limbs will automatically regenerate.
- Advanced Rad Poisoning causes a loss of 2 points of Endurance and 1 point of Agility. That is -4 to Big Guns and Unarmed, as well as -2 to Small Guns, Sneak, and total Action Points.
- Adamantium Skeleton is better at protecting limbs from crippling injury, yet it carries no penalties. However, Rad Regeneration is easier to get, and having the regeneration active means you don't have to deal with the effects of crippled limbs; as soon as the limb becomes crippled, it starts healing, and even having a single point of 'limb health' means that the limb is no longer crippled. For best results, use both perks.
- The perk still exists in the game files of Fallout: New Vegas, albeit only as legacy content.