Regenerative Peripheral Nerve Interfaces for Restoring Individual Finger Movement in Transhumeral Amputees

University Of Michigan At Ann Arbor, Ann Arbor MI

Investigators

Abstract

Project Summary There are millions of people worldwide with debilitating upper limb amputations. While electrical signals from residual muscles can provide some function, every person with amputation is missing muscles, and therefore missing a variety of important functions. This is particularly problematic when the amputation is above the elbow. Our group has demonstrated a novel method for obtaining signals from independent nerve branches in humans, which we call the Regenerative Peripheral Nerve Interface (RPNI). The small muscle grafts degenerate, regenerate, revascularize, and reinnervate utilizing natural biologic processes. Our long-term goal is to make nerve-controlled prostheses widely available, such that multi-articulated hands can be controlled as intuitively as an anatomic limb. We have evaluated this to date with chronic implants in four people with amputations below the elbow. The objective of the present application, which represents our proposed next step, is to use RPNIs to generate useful prosthetic control signals in people with amputations at the transhumeral level who have very little residual musculature for controlling finger movements. In Aim 1, we will recruit people with a transhumeral upper limb amputation, for which we already have FDA IDE approval for up to 6 additional study participants. We will evaluate the amplitude, movement specificity, and stability of RPNI signals recorded from nerves for 18 months post implant. We hypothesize that they will either increase or remain stable over time. In Aim 2, we will assess functional performance of prosthetic wrist and finger movements using these signals both inside and outside of the lab, including in a study at the participant's home. Finally in Aim 3, we will characterize the quality and consistency of referred sensation induced by stimulation of RPNIs at the transhumeral level. We hypothesize that this will elicit stable percepts referred to the phantom limb and improve task performance. In all cases RPNI signals will be compared to the clinical state of the art using surface EMG. We have partnered with industry (Ossur, Synapse Biomedical, Cirtec Biomedical) to provide different elements of our prototype nerve- controlled prosthesis. We believe successful completion of these aims will motivate commercialization and widespread use of RPNIs for prosthetic control.