An interventional study of Intramuscular electrodes in Amputation and Prostheses and Implants, sponsored by University of Michigan. Recruiting at 1 site in United States. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-05-19.
Sponsored by University of Michigan · Not applicable, Interventional, and Basic science
Individuals with an above-knee lower limb amputation are known to walk more slowly, expend more energy, have a greater risk of falling, and have reduced quality of life compared to individuals without amputation and those with below knee amputation. One of the driving factors behind these deficits is the lack of active function provided by above-knee prostheses with prosthetic knees and ankles. While many prosthetic devices have been developed for functional restoration after major lower extremity amputation, there remains no stable interface to facilitate reliable, long-term volitional control of an advanced robotic limb capable moving multiple joints. Moreover, there is no existing interface that provides useful sensory feedback that in turn enhances the functional capabilities of the prosthesis. To achieve both greater signal specificity and long-term signal stability, we have developed a biologic interface known as the Regenerative Peripheral Nerve Interface (RPNI). An RPNI consists of a peripheral nerve that is implanted into a free muscle graft that would otherwise go unused in the residual limb. As the nerve grows, it reinnervates the free muscle graft which undergoes a predictable sequence of revascularization and regeneration.
The main questions it aims to answer are:
Consenting participants with unilateral transfemoral amputation (TFA) will:
Background: While many prosthetic devices have been developed for functional restoration after major lower extremity amputation, there is no stable interface to provide reliable, long-term volitional control of an advanced robotic limb capable of multiple degrees of freedom. Moreover, there is no existing interface that provides useful sensory feedback that in turn enhances the functional capabilities of the prosthesis. To address these limitations, the investigators propose use of a novel biologic interface known as the Regenerative Peripheral Nerve Interface (RPNI). An RPNI consists of a peripheral nerve that is implanted into a free muscle graft. As the nerve grows, it reinnervates the free muscle graft which undergoes a predictable sequence of revascularization and regeneration. The RPNI leverages these biological processes to provide three essential benefits to people with amputation: 1) intuitive motor control, 2) sensory feedback, and 3) reduction of post-amputation pain.
Objective/Hypotheses: The objective of this application is to (1) determine the extent to which the RPNIs enable generation of high-fidelity motor control signals for a powered knee-ankle prosthesis and (2) demonstrate that meaningful sensory feedback can be generated from stimulation of sciatic nerve RPNIs.
Specific Aims: The specific aims are to: (1) Evaluate the amplitude, movement specificity and stability of sciatic nerve RPNI electromyography (EMG) signals up to one year post RPNI surgery, (2) Assess functional movement performance using sciatic nerve RPNI signals for control of a physical motorized prosthetic leg with multiple degrees of freedom, and (3) Determine whether stimulation of sciatic nerve RPNIs provides meaningful sensory feedback.
Study design: This project is the first clinical investigation of RPNIs in people with lower-limb amputation. The study will recruit 3 individuals with transfemoral amputation. RPNIs will be surgically constructed on the sciatic nerve and intramuscular electrodes will be implanted into these RPNIs and residual muscles. Experiments will then be conducted at regular intervals up to one year post RPNI surgery. These experiments will measure the EMG signals generated by RPNIs in response to volitional movement of the phantom limb. These signals will then be used to control a two-joint powered prosthesis during cyclic and unpredictable movements. Functional movement, pain, and other patient-reported outcomes will be collected for data analysis. Additionally, RPNIs will be electrically stimulated to elicit sensation. Stimulation will also be provided during the performance of functional tasks.
At the completion of data collection, participants will undergo electrode explantation and complete a postoperative visit to assess recovery, pain and any associated adverse events.
University of Michigan is the lead sponsor of 1,475 studies on the registry; 196 are open to participants now.
Of its 162 completed or terminated interventional studies of FDA-regulated products, 128 (79%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Participants will have regenerative peripheral nerve interfaces (RPNIs) created on nerves in their residual thighs. During either the same surgery or a separate surgery, electrodes will be implanted into these RPNIs.
Device: Intramuscular electrodes
Participants will have regenerative peripheral nerve interfaces (RPNIs) created on nerves in their residual thighs. During either the same surgery or a separate surgery, small electrodes will be implanted into these RPNIs.
Intensity of pain in residual and phantom limbs
Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity-Short Form 3a
Time frame: through study completion, an average of 1 year
Neuropathic Pain in residual limb
Leeds Assessment of Neuropathic Symptoms and Signs (LANSS)
Time frame: through study completion, an average of 1 year
Health-Related Quality of Life
Participants will complete the RAND 36-Item Short Form Health Survey (SF-36)
Time frame: through study completion, an average of 1 year
Amplitude and signal-to-noise ratio for each RPNI
Participants will be instructed to make large, sustained movements with their phantom lower extremity while in a seated position to estimate their maximum voluntary contraction. They will repeat this process five times for each movement. The signal-to-noise ratio (SNR) will be calculated as the ratio of that signal to the quiescent period signals.
Time frame: Postoperatively at each experimental visit at 3,6,9 & 12 months
Classification accuracy for movements of the phantom limb
Participants will move their phantom limb to match a virtual limb shown on a screen. We will measure how accurately we can predict the intended movement using muscle activity signals from RPNIs and residual muscles
Time frame: Postoperatively at each experimental visit at 3,6,9 & 12 months
Threshold for sensation after electrical stimulation of RPNI
We will stimulate RPNIs electrically through the implanted electrodes. We will quantify the charge necessary for the participant to feel sensation (perception threshold) and the minimum charge that becomes uncomfortable (discomfort threshold). We will also record the location and quality of the sensation felt at each threshold
Time frame: Postoperatively at each experimental visit at 3,6,9 & 12 months
Plan to share: No
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University of Michigan