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Magnetic Bead Tracking System for Transtibial Amputation Prosthetic Control

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What is being tested

Magnetic Bead Tracking System

Device
Who is being recruted

Transtibial Amputee

+ Transtibial Amputation
From 22 to 65 Years
+24 Eligibility Criteria

See all eligibility criteria

How is the trial designed

Treatment Study

Early Phase 1
Interventional
Study Start: September 2025

See protocol details

Summary

Principal SponsorMuscleMetrix, LLC
Study ContactDeborah Grayeski, JD
Last updated: September 26, 2025
Sourced from a government-validated database.Claim as a partner
Study start date: September 11, 2025Actual date on which the first participant was enrolled.

This study aims to explore the safety and effectiveness of a new technology called the Magnetic Bead Tracking System, which is designed to help individuals with lower-leg amputations control a prosthetic ankle-foot device. The study focuses on people with transtibial, or below-the-knee, amputations. This technology could potentially improve the way people with prosthetic limbs move by providing more natural and intuitive control. The goal is to see if this system can provide better control compared to existing prosthetic controllers, which could greatly enhance the quality of life for individuals using prosthetics. Participants in the study will have a small number of magnetic beads implanted in their residual limb muscles. These beads, along with external sensors, will track muscle movements to help control the prosthetic limb. The study will measure how well participants can walk and navigate obstacles using this system compared to a traditional prosthetic control system. Safety is a major focus, with any potential side effects being closely monitored throughout the study. Participants will be asked to report how they feel and will undergo regular check-ups to ensure the system is safe and effective. The study will gather both qualitative and quantitative data to evaluate improvements in walking speed and maneuverability.

Official TitleA Feasibility Study Evaluating the Magnetic Bead Tracking System and Its Safety and Effectiveness When Used With a Bionic External Prosthesis to Improve Prosthetic Controllability for Persons With Transtibial Amputation 
Principal SponsorMuscleMetrix, LLC
Study ContactDeborah Grayeski, JD
Last updated: September 26, 2025
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.
Design Details
3 patients to be enrolledTotal number of participants that the clinical trial aims to recruit.
Treatment Study
These studies test new ways to treat a disease, condition, or health issue. The goal is to see if a new drug, therapy, or approach works better or has fewer side effects than existing options.

How participants are assigned to different groups/arms
In this clinical study, all participants receive the same treatment. Since there is only one group, there is no need for randomization or assignment to different arms. This type of study is often used to test a new treatment without comparing it to another.

Other Ways to Assign Participants
Randomized allocation: Participants are assigned randomly, like flipping a coin, to ensure fairness and reduce bias.
Non-randomized allocation: Participants are assigned based on specific factors, such as their medical condition or a doctor's decision.

How treatments are given to participants
In this study, all participants receive the same treatment. This approach is often used to evaluate the effects of a single intervention without comparing it to another.

Other Ways to Assign Treatments
Parallel assignment: Participants are split into separate groups, each receiving a different treatment.
Cross-over assignment: Participants switch between treatments during the study.
Factorial assignment: Participants receive different combinations of treatments.
Sequential assignment: Participants receive treatments one after another in a specific order, possibly based on individual responses.
Other assignment: Treatment assignment does not follow a standard or predefined design.

How the effectiveness of the treatment is controlled
In a non placebo-controlled study, no participants receive an inert substance (placebo) to compare outcomes. Instead, all participants receive either the experimental treatment or an alternative treatment (often the Standard of Care). This method allows researchers to compare the effects of the experimental treatment with those of a different active intervention, rather than a placebo.

Other Options
Placebo-Controlled: A placebo is used to compare the effects of the experimental treatment with those of an inert substance, isolating the true treatment effect.

How the interventions assigned to participants is kept confidential
Everyone involved in the study knows which treatment is being given. This is typically used when it's not possible or necessary to hide the treatment details from participants or researchers.

Other Ways to Mask Information
Single-blind: Participants do not know which treatment they are receiving, but researchers do.
Double-blind: Neither participants nor researchers know which treatment is given.
Triple-blind: Participants, researchers, and outcome assessors do not know which treatment is given.
Quadruple-blind: Participants, researchers, outcome assessors, and care providers all do not know which treatment is given.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Conditions
Criteria
Any sexBiological sex of participants that are eligible to enroll.
From 22 to 65 YearsRange of ages for which participants are eligible to join.
Healthy volunteers not allowedIf individuals who are healthy and do not have the condition being studied can participate.
Conditions
Pathology
Transtibial Amputee
Transtibial Amputation
Criteria
10 inclusion criteria required to participate
Male or Female age 22-65 at the time of surgery
The patient must already have an existing unilateral or bilateral transtibial amputation requiring revision or a medical condition requiring performance of a unilateral or bilateral transtibial amputation
If the patient does not already have an amputation, the patient must have undergone independent consultation with a lower extremity surgical specialist to ensure they have exhausted all limb salvage options prior to undergoing amputation, as well as a psychiatric evaluation to ensure appropriate capacity and volition, and a pain medicine evaluation to ensure that all pain control options outside of amputation have been addressed
The patient must have the ability to ambulate at variable cadence (an expected lower extremity prosthesis functional level of K3 or above, as determined by a trained and certified prosthetist and confirmed by study investigators, through use of a patient history and physical examination)

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14 exclusion criteria prevent from participating
Patients with any active skin disease in the subject limb
Patients with severe comorbidity, atypical skeletal anatomy, or poor general physical/mental health that, in the opinion of the Investigator, will not allow the patients to be a good study candidate (i.e., other disease processes, mental capacity, substance abuse, shortened life. expectancy, vulnerable patient population, etc.)
Patients with the following concurrent diseases: active infection or dormant bacteria, metabolic bone disease and/or metastatic lesions in the residual tibia
Patients weighing over 285 lbs. with the prosthesis, at time of screening

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Study Plan

Find out more about all the medication administered in this study, their detailed description and what they involve.
Treatment Groups
Study Objectives
One single intervention group 

is designated in this study

This study does not include a placebo group 

Treatment Groups
Group I
Experimental
Up to five subjects signing an informed consent and meeting all inclusion and exclusion criteria will be enrolled into the study to receive the Magnetic Bead Tracking System. Each subject will serve as their own control in a repeated measures ('within subjects') design. During experimentation, each subject will have prosthetic gait performance measured while using the Magnetic Bead Tracking System compared to an intrinsic robotic controller.
Study Objectives
Primary Objectives

The preferred and fastest walking speeds across level-ground and uneven walking surfaces will be measured as the primary study variables for AIM 1. To make these measurements, the time duration will be measured for each study subject to walk at steady state speed overground across 10m walkways at their preferred and fastest walking speeds. Subjects will receive standardized instructions encouraging them to either walk at their comfortable walking speed, or at their maximum walking speed, across each level-ground andan uneven 10m walkway. The investigators expect that the preferred and maximum speeds will be higher when employing the magnetomicrometry (MM) prosthetic controller compared to the commercial intrinsic controller, in support of the H1 hypothesis.

The time to traverse an obstacle course will be evaluated to test obstacle avoidance, changes in walking direction, slope/stair variations, and speed transients, testing the ability of each controller to deliver rapid gait maneuvers while subjects walk across the unstructured environment. The investigators expect that the time to complete the obstacle course will be lower when employing the MM controller compared to the commercial intrinsic controller, further supporting the H1 hypothesis.
Secondary Objectives

The Six Minute Walk Test (6MWT) across a level-ground surface will be evaluated, or the maximum distance a person can walk in a six-minute period. Using an indoor track, the total distance each subject can walk throughout a six-minute interval will be measured for each controller (magnetomicrometry (MM) vs. Intrinsic). The investigators expect that the 6MWT will be higher when employing the MM prosthetic controller compared to the commercial intrinsic controller, further supporting the H1 hypothesis.

Asymmetry between the double-support time preceding intact limb (tdspi) and preceding prosthetic limb (tdsip) transitions will be measured on level ground and slopes (instrumented treadmill), and for stair ascent and descent. The investigators expect that a composite measure of Gait Symmetry will demonstrate the best performance when the powered ankle-foot prosthesis is controlled using the MM controller, further supporting the H1 hypothesis.

Prosthetic and unaffected leg ankle net-work, wA , will be measured as defined in \[2\] on level ground and slopes (instrumented treadmill), and for stair ascent and descent. The investigators expect that the net-work measures when employing the MM controller will more closely match that of the contralateral intact ankle than compared to the commercial intrinsic controller, further confirming the H1 hypothesis.

Bilateral knee moments will be measured as defined in on level ground and slopes (instrumented treadmill). The investigators expect the contralateral knee adduction moment measure of musculoskeletal stress to be lowered when employing the MM controller as compared with the intrinsic controller, further supporting the H1 hypothesis.

Posturographic parameters will be derived from pelvic center of mass (COM) position collected as subjects stand on a one axis (anteroposterior) balance board. The investigators expect that stability metrics will show the best performance when the powered ankle-foot prosthesis is controlled using the MM interface as compared with the intrinsic controller, further supporting the H1 hypothesis.

The relative pain levels experienced by the user at the unaffected knee and lower back will be assessed using a Visual Analogue Scale (VAS, 0 to 10). The investigators expect a lower pain score when the powered ankle-foot prosthesis is configured for the MM controller as compared with the intrinsic controller, further supporting the H1 hypothesis.

Patient-reported mobility will be assessed as measured by the Prosthetic Limb Users Survey of Mobility (PLUS-M). The investigators expect a score of greater than or equal to 5 when using the MM controller, indicating a significant improvement in mobility compared to the commercial intrinsic controller.

Patient-reported embodiment will be assessed as measures by the Prosthesis Embodiment Scale for Lower Limb Amputees (PEmbS-LLA). PEmbS-LLA is a 10-item, patient-reported questionnaire (using a 7-point Likert scale) designed to measure how well a lower limb amputee integrates their prosthesis into their body representation and sense of self.The investigators expect a higher level of embodiment when using the MM controller compared to the commercial intrinsic controller.

Equilibrium scores, limits of stability, symmetry, and latency and amplitude of response to perturbation will be assessed from Computerized Dynamic Posturography (CDP). The investigators expect that stability metrics will show the best performance when the powered ankle-foot prosthesis is controlled using the MM interface as compared with the intrinsic controller, further supporting the H1 hypothesis.

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.
This study has 1 location
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Brigham and Women's HospitalBoston, United StatesSee the location
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One Study Center