Regenerative Peripheral Nerve Interface (RPNI)
Researchers at the University of Michigan study regenerative peripheral nerve interfaces (RPNIs) as a potential means of improving prosthetic-limb control, providing sensory feedback, and reducing pain following amputation.
Please visit our frequently asked questions (FAQ) page to see answers to commonly asked questions.
A regenerative peripheral nerve interface (RPNI) is a biologic interface created by connecting the end of a severed peripheral nerve to a small free muscle graft. As the nerve grows into the muscle, the muscle provides a healthy target for regenerating nerve fibers and can generate electrical signals related to the user's intended movement.
An RPNI is created in a surgical procedure, done either at the time of amputation or months to years later. The procedure generally takes 2–4 hours.
The surgeon locates the nerve endings in the remaining limb and may separate the main nerve into smaller individual strands, called fascicles. If painful neuromas have already formed, they're trimmed away first.
Each nerve or nerve fascicle is centered over a small piece of healthy muscle (the graft).
The muscle is sewn to the nerve with fine thread, securing it in place.
The muscle is rolled over the end of the nerve and stitched closed, then tucked into a well-vascularized part of the limb to heal.
Researchers at the University of Michigan are using small electrodes implanted into RPNIs and other muscles in the residual limb to try to improve prosthetic control. Researchers are also studying whether electrical stimulation of RPNIs can evoke meaningful sensations that may eventually be used to provide sensory feedback from prosthetic devices. These studies are being done at various levels of amputation, including transhumeral (between the shoulder and elbow), transradial (between the elbow and wrist) and transfemoral (between the hip and knee)
Want to participate in research? Reach out to rpnistudy@umich.edu for more information!
We are currently recruiting participants for the following studies:
RPNIs for upper limb prosthetic control and sensation (transradial and transhumeral)
RPNIs for lower limb prosthetic control and sensation (transfemoral)
Select a study above to view additional information on ClinicalTrials.gov. age at ClinicalTrials.gov.
Turning Thought into Action - A friendly introduction to the University of Michigan’s RPNI prosthesis research, featuring first-hand accounts from past and current participants.
Regenerative Peripheral Nerve Interface Surgery: Anatomic and Technical Guide - A technical guide to how RPNI surgery works. Please note that this link includes surgical photographs, so view with caution.
RPNI Lowers Post Amputation Pain - Details on how RPNIs help manage amputation-related pain. Please note that this link includes surgical photographs, so view with caution.
Published in IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2024.
Published in IEEE Transactions on Medical Robotics and Bionics, 2025.
Published in the Journal of Neural Engineering, 2022.
Published in IEEE Engineering in Medicine and Biology Society, 2025.
Published in the Journal of Neural Engineering, 2023.
