# Agonist-Antagonist Myoneural Interface for Functional Limb Restoration after Transtibial Amputation

> **NIH NIH R01** · MASSACHUSETTS INSTITUTE OF TECHNOLOGY · 2020 · $586,841

## Abstract

Project Summary/Abstract
Humans have the ability to precisely sense the position, speed, and torque of their body parts. This sense is
known as proprioception. In the many attempts to create human-mechatronic interactions there is still no
robust, repeatable methodology to reflect proprioceptive information from a synthetic device onto the nervous
system. The study presents a novel bi-directional neural communication paradigm – called the Agonist-
antagonist Myoneural Interface (AMI) – for functional limb restoration after transtibial amputation. The AMI is a
neural communication architecture comprised of two muscles – an agonist and an antagonist – surgically
connected in series within the amputated residuum so that contraction of one muscle stretches the other. The
AMI preserves important dynamic muscle relationships that exist within native anatomy, thereby allowing
proprioceptive signals from mechanoreceptors within both muscles to be communicated to the central nervous
system. It is hypothesized that surgically-constructed AMIs, created within the residuum during limb
amputation, can afford an improved independent control of joint position and impedance in a multi-degree-of-
freedom prosthesis while also reflecting proprioceptive sensation from each prosthetic joint onto the central
nervous system. Following a prospective, case-control intervention model, we recruit healthy, active
participants with transtibial amputations with and without the novel AMI surgical intervention. Each subject in
the intervention group has an amputated residuum comprising two AMIs, enabling clinically translatable studies
of myoelectric control of a prosthesis with actuated ankle and subtalar joints, and experimental demonstrations
of closed-loop prosthetic joint torque control. Specific Aim 1 investigates if AMIs can improve control over
voluntary prosthesis movement. Specific Aim 2 determines if AMIs can preserve involuntary (reflexive) gait
behaviors during irregular terrain ambulation. Specific Aim 3 explores if an AMI construct can provide closed-
loop joint torque control with somatotopically-matched force feedback. The research design includes the
collection of electromyography, ultrasound, biomechanical (kinematic and kinetic), and psychometric data.
Closed-loop joint torque control is provided through functional electrical stimulation. The extent of functional
limb restoration enabled by the AMIs will be assessed using metric-based performance evaluations. Through
insights on the capabilities of surgically-created bi-directional neural interfaces, the study provides a framework
for integrating bionic systems with human physiology to improve the health, productivity, independence, and
quality of life of persons with amputations.

## Key facts

- **NIH application ID:** 9893886
- **Project number:** 5R01HD097135-02
- **Recipient organization:** MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** HUGH M HERR
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $586,841
- **Award type:** 5
- **Project period:** 2019-03-14 → 2024-02-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9893886

## Citation

> US National Institutes of Health, RePORTER application 9893886, Agonist-Antagonist Myoneural Interface for Functional Limb Restoration after Transtibial Amputation (5R01HD097135-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9893886. Licensed CC0.

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