AmputationNCT06138977
Controlling Locomotion Over Continuously Varying Activities for Agile Powered Prosthetic Legs
A study testing Powered prosthesis in people with Amputation, run by University of Michigan at 1 site in United States.
Trial summary
The overall goal of this project is to model human joint biomechanics over continuously-varying locomotion to enable adaptive control of powered above-knee prostheses. The central hypothesis of this project is that variable joint impedance can be parameterized by a continuous model based on measurable quantities… Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Amputation
- What is being tested?
- Powered prosthesis
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 6 Dec 2023to 30 Jan 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged between 18 to 65 years
- Exclusion criteria for able-bodied, young adult participants will be:
- Pregnant (self-report)
- Any significant neuromuscular or musculoskeletal disorder that would interfere with the study
- Unable to walk for 20 minutes
- History of any cardiovascular, vestibular, or visual diseases and/or impairments that may interfere with the study
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- Cognitive deficits that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. In the case of screening for cognitive deficits, the consenting researcher will ask the subject if he/she has any prior history of cognitive deficits.
- Adults with a known allergy to medical grade tape
- Aged between 18 to 70 years.
- Weigh less than 250 lbs due to limitations in the design of the prosthesis.
- Amputee subjects will be more than two months post independent ambulation with an amputation at the transfemoral level in order to use the above-knee prosthesis.
- Amputee subjects will have a mobility classification of K2/K3/K4 ambulators (minimum community ambulatory) and have the ability to ambulate without an assistive device beyond their prosthesis.
Who cannot join
- Weigh over 250 pounds body
- Pregnant (self-report)
- Any significant neuromuscular or musculoskeletal disorder that would interfere with the study
- Inactive or physically unfit, unable to walk for 20 minutes
- An excessively long residual limb length, and/or a non-removable cosmetic cover determined by the prosthetist performing the evaluations
- Cognitive deficits or visual impairment that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. In the case of screening for cognitive deficits, the consenting researcher will ask the subject if he/she has any prior history of cognitive deficits.
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- Co-morbidity that interferes with the study (e.g., pace maker placement, severe ischemia, cardiac disease, etc.)
- Adults unable to consent
- Adults with a known allergy to medical grade tape
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Rehab Lab, University of Michigan
Ann Arbor, Michigan, 48109
Kashvi Pota, MS, 734-763-1156, kashvip@umich.edu
About this study
The overall goal of this project is to model human joint biomechanics over continuously-varying locomotion to enable adaptive control of powered above-knee prostheses. The central hypothesis of this project is that variable joint impedance can be parameterized by a continuous model based on measurable quantities called phase and task variables. This project will use machine learning to identify variable impedance functions from able-bodied data including joint perturbation responses across the phase/task space to bias the solution toward biological values.
Read the detailed description
The overall goal of this project is to model human joint biomechanics over continuously-varying locomotion to enable adaptive control of powered above-knee prostheses. Above-knee amputees often struggle to perform the varying activities of daily life with conventional prostheses due to the lack of positive mechanical work and active control. Emerging powered prostheses have motors that can perform these missing functions, but the biomechanics experienced by the user depend on the control of these motors. The way the prosthesis interacts with both the user and environment can be controlled through joint impedance--the relationship between joint motion and torque. Prosthetic joint impedance is typically defined via a stiffness, viscosity, and equilibrium angle for discrete phases of gait within a limited set of discrete activities, but this framework does not allow continuous variations of steady-state activities (e.g., walking at different speeds/inclines) or continuous transitions between activities (e.g., walk to stair ascent). The central hypothesis of this project is that variable joint impedance can be parameterized by a continuous model based on measurable quantities called phase and task variables. This project will use machine learning to identify variable impedance functions from able-bodied data including joint perturbation responses across the phase/task space to bias the solution toward biological values. The resulting impedance model will be used with real-time estimates of phase and task variables to control a custom powered knee-ankle prosthesis and the Ossur PowerKnee across activities. The clinical trial will comprise the following human subject experiments.
Aim 1.3: N=5 able-bodied subjects will be recruited for initial testing of the walking and stair controllers. Once the powered knee-ankle prosthesis achieves satisfactory performance, we will enroll N=5 amputee subjects to validate these controllers.
Aim 2.3: N=5 able-bodied subjects will be recruited for initial testing of the sit-to-stand and walk-stair transition controllers. Once the powered knee-ankle prosthesis achieves satisfactory performance, we will enroll N=5 amputee subjects to validate these controllers.
Aim 3.1: N=5 amputee subjects will be enrolled to validate the clinical interface for the powered prosthesis controllers.
Aim 3.2: N=5 amputee subjects will be enrolled to validate the transfer of the controllers to the PowerKnee.
Aim 3.3: N=10 amputee subjects will be enrolled in a study of endurance and symmetry outcomes with the PowerKnee compared to their take-home prosthesis.
- Conditions
- Amputation
- Being tested
- Powered prosthesis
- Keywords
- prosthetic leg
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Powered prosthesisDevice
A powered prosthesis will be used to restore normative leg biomechanics to above-knee amputee participants during different activities of daily life.
| Study group | Role | What they receive |
|---|---|---|
| Prosthesis | Experimental | Participants in this arm of the study will perform various tasks while wearing the powered prosthesis Receives: Device: Powered prosthesis |
What is being measured
The primary outcome is the main question the study is designed to answer.
Joint work
Mechanical work at the prosthetic knee and ankle will be assessed for participants using the powered prosthesis in A1.3 and A2.3, with comparisons to able-bodied averages. Joint work will be calculated by multiplying the joint's commanded torque by its measured velocity, resulting in units of Joules.
Measured: 1 day
Tuning time
The time for a prosthetist to configure the powered prosthesis for above-knee amputee participants will be assessed in A3.1 and A3.3.
Measured: 1 day
Endurance test time
The time to complete multiple cycles through an ambulation circuit will be recorded with above-knee amputee participants' take-home prosthesis and a powered prosthesis. The ambulation circuit comprises, sit-to-stand, walking, stair ascent/descent, ramp descent/ascent, and stand-to-sit.
Measured: 1 day
Secondary outcomes (6)
Inter-leg symmetry
Kinematic and kinetic symmetry will be assessed between the sound side and prosthetic side of participants using the powered prosthesis in A1.3 and A2.3, with comparisons to able-bodied averages. The units will be % difference between legs, where 0% indicates perfect symmetry.
Measured: 1 day
Stance-swing time ratio
The stance-swing time ratio will be assessed for participants using the powered prosthesis in A1.3 and A2.3, with comparisons to able-bodied averages. The stance-swing time ratio for above-knee amputee participants will compared between their take-home prosthesis and a powered prosthesis in A3.3.
Measured: 1 day
Step time symmetry
Step time symmetry (between sound and prosthetic side) of above-knee amputee participants will compared using their take-home prosthesis and a powered prosthesis in A3.3. The units will be % difference between legs, where 0% indicates perfect symmetry.
Measured: 1 day
Step length symmetry
Step length symmetry (between sound and prosthetic side) of above-knee amputee participants will compared using their take-home prosthesis and a powered prosthesis in A3.3. The units will be % difference between legs, where 0% indicates perfect symmetry.
Measured: 1 day
Step width symmetry
Step width symmetry (between sound and prosthetic side) of above-knee amputee participants will compared using their take-home prosthesis and a powered prosthesis in A3.3. The units will be % difference between legs, where 0% indicates perfect symmetry.
Measured: 1 day
Prosthesis Evaluation Questionnaire-Mobility
Amputee participant responses to the Prosthesis Evaluation Questionnaire-Mobility Subscale will be compared between the take-home leg and powered leg in A3.3. Questions will be answered on a scale from 0 (extremely dissatisfied) to 5 (extremely satisfied).
Measured: 1 day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Nov 2023
- Study start6 Dec 2023
- Primary completion30 Jan 2028 (estimated)
- Study completion30 Jan 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for AmputationStudies of the same condition, open and under way.
- More trials run by University of MichiganThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Michigan
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Robert D Gregg, University of Michigan
- Investigators
- Robert D Gregg, PhD, Principal investigator, University of Michigan
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06138977
- Sponsor's protocol ID
- HUM00230065
- Status last verified
- Sep 2026
- First submitted
- 13 Nov 2023
- Last updated
- 16 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- Yes: De-identified IPD will be shared upon publication.
Publications
Best TK, Seelhoff CA, Wensman J, Gregg RD. The clinical effects of the Ossur Power Knee with phase-based and default control during sitting, standing, and walking. J Neuroeng Rehabil. 2025 Sep 29;22(1):200. doi: 10.1186/s12984-025-01729-2.
PubMed 41024213
Study at a glance
From the registry record, last updated by the sponsor on 16 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Controlling Locomotion Over Continuously Varying Activities for Agile Powered Prosthetic Legs
- ClinicalTrials.gov ID
- NCT06138977
- Acronym / sponsor ID
- HUM00230065
- Conditions
- Amputation
- Keywords
- prosthetic leg
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- University of MichiganUniversity, hospital or other
- Study start
- 6 Dec 2023 (actual)
- Primary completion
- 30 Jan 2028 (estimated)
- Study completion
- 30 Jan 2028 (estimated)
- First posted
- 18 Nov 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The overall goal of this project is to model human joint biomechanics over continuously-varying locomotion to enable adaptive control of powered above-knee prostheses. The central hypothesis of this project is that variable joint impedance can be parameterized by a continuous model based on measurable quantities called phase and task variables. This project will use machine learning to identify variable impedance functions from able-bodied data including joint perturbation responses across the phase/task space to bias the solution toward biological values.
Detailed description
The overall goal of this project is to model human joint biomechanics over continuously-varying locomotion to enable adaptive control of powered above-knee prostheses. Above-knee amputees often struggle to perform the varying activities of daily life with conventional prostheses due to the lack of positive mechanical work and active control. Emerging powered prostheses have motors that can perform these missing functions, but the biomechanics experienced by the user depend on the control of these motors. The way the prosthesis interacts with both the user and environment can be controlled through joint impedance--the relationship between joint motion and torque. Prosthetic joint impedance is typically defined via a stiffness, viscosity, and equilibrium angle for discrete phases of gait within a limited set of discrete activities, but this framework does not allow continuous variations of steady-state activities (e.g., walking at different speeds/inclines) or continuous transitions between activities (e.g., walk to stair ascent). The central hypothesis of this project is that variable joint impedance can be parameterized by a continuous model based on measurable quantities called phase and task variables. This project will use machine learning to identify variable impedance functions from able-bodied data including joint perturbation responses across the phase/task space to bias the solution toward biological values. The resulting impedance model will be used with real-time estimates of phase and task variables to control a custom powered knee-ankle prosthesis and the Ossur PowerKnee across activities. The clinical trial will comprise the following human subject experiments.
Aim 1.3: N=5 able-bodied subjects will be recruited for initial testing of the walking and stair controllers. Once the powered knee-ankle prosthesis achieves satisfactory performance, we will enroll N=5 amputee subjects to validate these controllers.
Aim 2.3: N=5 able-bodied subjects will be recruited for initial testing of the sit-to-stand and walk-stair transition controllers. Once the powered knee-ankle prosthesis achieves satisfactory performance, we will enroll N=5 amputee subjects to validate these controllers.
Aim 3.1: N=5 amputee subjects will be enrolled to validate the clinical interface for the powered prosthesis controllers.
Aim 3.2: N=5 amputee subjects will be enrolled to validate the transfer of the controllers to the PowerKnee.
Aim 3.3: N=10 amputee subjects will be enrolled in a study of endurance and symmetry outcomes with the PowerKnee compared to their take-home prosthesis.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Prosthesis | Experimental | Device: Powered prosthesisParticipants in this arm of the study will perform various tasks while wearing the powered prosthesis |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (12 listed)
- Aged between 18 to 65 years
- Pregnant (self-report)
- Any significant neuromuscular or musculoskeletal disorder that would interfere with the study
- Unable to walk for 20 minutes
- History of any cardiovascular, vestibular, or visual diseases and/or impairments that may interfere with the study
Key exclusion criteria (9 listed)
- Weigh over 250 pounds body
- Pregnant (self-report)
- Any significant neuromuscular or musculoskeletal disorder that would interfere with the study
- Inactive or physically unfit, unable to walk for 20 minutes
- An excessively long residual limb length, and/or a non-removable cosmetic cover determined by the prosthetist performing the evaluations
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Powered prosthesisA powered prosthesis will be used to restore normative leg biomechanics to above-knee amputee participants during different activities of daily life. | Device | Prosthesis |
Primary outcome
Joint work
Time frame: 1 day
Mechanical work at the prosthetic knee and ankle will be assessed for participants using the powered prosthesis in A1.3 and A2.3, with comparisons to able-bodied averages. Joint work will be calculated by multiplying the joint's commanded torque by its measured velocity, resulting in units of Joules.
Tuning time
Time frame: 1 day
The time for a prosthetist to configure the powered prosthesis for above-knee amputee participants will be assessed in A3.1 and A3.3.
Endurance test time
Time frame: 1 day
The time to complete multiple cycles through an ambulation circuit will be recorded with above-knee amputee participants' take-home prosthesis and a powered prosthesis. The ambulation circuit comprises, sit-to-stand, walking, stair ascent/descent, ramp descent/ascent, and stand-to-sit.
6 secondary outcomes
Inter-leg symmetry
Time frame: 1 day
Stance-swing time ratio
Time frame: 1 day
Step time symmetry
Time frame: 1 day
Step length symmetry
Time frame: 1 day
Step width symmetry
Time frame: 1 day
Prosthesis Evaluation Questionnaire-Mobility
Time frame: 1 day
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Sep 2026.
- Derived from this study: PubMed 41024213Best TK, Seelhoff CA, Wensman J, Gregg RD. The clinical effects of the Ossur Power Knee with phase-based and default control during sitting, standing, and walking. J Neuroeng Rehabil. 2025 Sep 29;22(1):200. doi: 10.1186/s12984-025-01729-2.
- Individual participant dataSharing planned: Yes. De-identified IPD will be shared upon publication.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Robert D Gregg, PhD principal investigator
University of Michigan
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Powered prosthesis in people with Amputation, run by University of Michigan at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 12 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 16 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Kashvi Pota, MS (734-763-1156, kashvip@umich.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Joint work (time frame: 1 day). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06138977, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Sep 2026.