- For participants without existing RPNI grafts (at the time of enrollment), the residual limb must have sufficient soft tissue quality to support performance of the RPNI operative 305 8procedures. Participants sustaining severe crushing or avulsion injuries with substantial superficial and deep scarring may not be appropriate candidates for inclusion in the study. °Participants must be in good health and American Society of Anesthesiologists (ASA) Class I (low surgical risk).