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Transfemoral AmputeesNCT03204513

Impact of Powered Knee-Ankle Prosthesis Leg on Everyday Community Mobility and Social Interaction

A study testing Vanderbilt Powered Knee-Ankle Prosthesis and Microprocessor (MP) Knee Prosthesis in people with Transfemoral Amputees, run by Shirley Ryan AbilityLab at 1 site in United States.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

The overall goal of this research is to determine the efficacy of new powered prosthetic devices for individuals with transfemoral amputations. The anticipation is that this will be a high-impact technological intervention with the potential to restore significant functionality to individuals with lower limb… Read more about this study

Who is it for?
Ages 18 to 80 years
Conditions the study is for
Transfemoral Amputees
What is being tested?
Vanderbilt Powered Knee-Ankle Prosthesis and Microprocessor (MP) Knee Prosthesis
Type of treatment
Medical device
Could I receive a placebo?
No, everyone receives an active treatment
How many people
15 participants
Where
1 siteUnited States
Study dates
Dec 2016to Dec 2026
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 80 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Unilateral transfemoral level limb loss or limb difference
  • K2/K3/K4 level ambulators
  • Required to use a microprocessor knee on their prosthesis

Who cannot join

  • Over 250 lbs body weight
  • Inactive, physically unfit
  • Cognitive deficits or visual impairment that would impair their ability to give informed consent or to follow simple instructions during the experiments
  • Pregnant women
  • Co-morbidity that interferes with the study (e.g. stroke, pace maker placement, severe ischemia cardiac disease, etc.)

Trial locations and contacts

1 site in 1 country.

United States1 site
  • Shirley Ryan AbilityLab

    Chicago, Illinois, 60611

Other trials in United States

About this study

The overall goal of this research is to determine the efficacy of new powered prosthetic devices for individuals with transfemoral amputations. The anticipation is that this will be a high-impact technological intervention with the potential to restore significant functionality to individuals with lower limb amputation and transform the field of lower limb prosthetics. The objective of the proposed clinical trial is to fully evaluate the biomechanical and energetic effects of using PKA prosthesis and quantify functional performance and quality of life changes.

Read the detailed description

The overall goal of this research is to bring powered devices, with suitable advanced control systems, to the clinic and home. The anticipation is that this will be a high-impact technological intervention with the potential to restore significant functionality to individuals with lower limb amputation and transform the field of lower limb prosthetics.

The objective of the proposed clinical trial is to fully evaluate the biomechanical and energetic effects of using a powered knee-ankle prosthesis, identify task-specific training strategies for every-day device use, and quantify functional performance and quality of life changes at home and in the community. The hypothesis is that the powered knee-ankle prosthesis will demonstrate a significant improvement in function over existing technology. Furthermore, the hypothesis is that incorporating neural control information will provide enhanced, intuitive control of this device. Thus the approach is to directly compare the powered device with current state-of-art passive microprocessor controlled (MP) prostheses using a randomized cross-over study to control for subject-specific variation.

1.1 Aim 1: Perform in-laboratory training and testing to compare gait biomechanics and clinical performance over several ambulation modes using either a passive prosthesis or a powered prosthesis. The expectation is the PKA prosthesis to enable gait kinetics and kinematics that more closely resemble those of individuals with intact limbs, therefore lowering the biomechanical and metabolic effects of ambulation.

1.2 Aim 2: Perform home trials to evaluate community mobility and social interaction when using a powered knee-ankle prosthesis or a passive device. The expectation is that participants will choose to complete more diverse functional, occupational, and recreational activities when using the PKA prosthesis.

1.3 Aim 3: Quantify performance with the PKA device when using a novel intent recognition algorithm that allows for seamless transitioning between activities compared to a standard control method. The expectation is that pattern recognition- based control will further improve mobility and decrease the physiological costs of ambulation compared to using the standard control method.

Being tested
Vanderbilt Powered Knee-Ankle Prosthesis, Microprocessor (MP) Knee Prosthesis
Keywords
Prosthesis, Powered Prosthesis

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Vanderbilt Powered Knee-Ankle ProsthesisDevice

    Also called PKA Prosthesis, Powered Knee-Ankle Prosthesis

    The Vanderbilt powered prosthesis is a transfemoral prosthesis with powered and coordinated knee and ankle joints. The Generation 3 prosthesis is actuated by two brushless direct current (DC) motors, providing up to 100 Nm of torque at the knee joint, and with the assistance of a parallel stiffness, up to 200 Nm in plantar flexion at the ankle. Sensors measure knee and ankle joint angles, axial load in the shank, and position and orientation of the prosthesis in space (via a 6-axis inertial measurement unit). An onboard lithium-ion battery provides sufficient energy for approximately 10,000 steps between battery charges. The prosthesis prototype weighs approximately 4.3 kg (9.5 lb), the mass of which is approximately equivalent to the intact limb of a 48 kg (105 lb) person.

  • Microprocessor (MP) Knee ProsthesisDevice

    Participants enrolled will already have their own microprocessor controlled (MP) non-powered knee prostheses as per inclusion criteria. Examples: OttoBock's C-Leg, Ossur's Rheo, Freedom Plie, Endolite Orion,etc.

Study groups in NCT03204513
Study groupRoleWhat they receive
Vanderbilt Powered Knee-Ankle ProsthesisExperimentalUpon screening and enrollment participants return for up to 8 prosthetic fitting sessions and up to 12 physical therapy training sessions using the Vanderbilt Powered Knee-Ankle (PKA) Prosthesis. Once training is complete participants will return for up to 6 post-training assessment sessions using the Vanderbilt Powered Knee-Ankle (PKA) Prosthesis. The device participants begin with will be randomly selected but there will be an equal opportunity to train with both devices. In between training, there will be an 8 week "wash out period" to allow normalization to use of the device, reducing carryover effects. After wash-out period protocol will be repeated with second device.
Receives: Device: Vanderbilt Powered Knee-Ankle Prosthesis
Microprocessor (MP) Knee ProsthesisActive comparatorUpon screening and enrollment participants return for up to 8 prosthetic fitting sessions and up to 12 physical therapy training sessions using their own Microprocessor (MP) Knee Prosthesis. Once training is complete participants will return for up to 6 post-training assessment sessions using the Microprocessor (MP) Knee Prosthesis. The device participants begin with will be randomly selected but there will be an equal opportunity to train with both devices. In between training, there will be an 8 week "wash out period" to allow normalization to use of the device, reducing carryover effects. After wash-out period protocol will be repeated with second device.
Receives: Device: Microprocessor (MP) Knee Prosthesis

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change between devices of the Modified Graded Treadmill Test

    This test is used to determine participant's endurance while walking at different speeds on a motorized treadmill. Participants will be secured to an overhead safety harness during this test. Participants will walk for up to 2 minutes each at different speeds on the treadmill. The treadmill speeds will be varied between 0.2 meters/second up to 2.0 meters/second at increments of 0.2 meters/sec. Close to the end of every 2 minute walk period, the participant will be asked to rate the perceived exertion for the walking task. Before incrementing the speed and continuing with the test, participants will be asked if participants would like to continue to walk and if the speed can be incremented. Participants metabolic and heart rate will be monitored frequently and recorded during this test. A physical exertion rating scale will be used to record participant's perceived exertion during every 2 minutes throughout the trial.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  2. Change in Biomechanical Assessment [Gait Parameters and Surface Electromyography (EMG) Activation] Between Devices

    Surface EMG recording of specific muscles will be recorded during walking. The EMG electrodes detect electrical signals of the muscles. Reflective markers will be placed at specific locations on the upper and lower extremity joint/bony landmarks to record the motion while walking. The locations of the markers in space will be recorded by an infrared based multi-camera system during walking indoors on tile and over force plates.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

Secondary outcomes (14)
  1. Change in Manual Muscle Test (MMT)

    Muscle strength with be assessed using a hand held dynamometer for muscle strength testing of the lower limb

    Measured: Week 1 (Pre-Assessment); Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  2. Change in Passive Range of Motion (PROM)

    Lower extremity PROM and AROM will be measured using an electrogoniometer. This is a computerized device capable of measuring angles and giving an electronic output of the measurements. This device has been found to have high ratings of reliability and validity in the lower limb.

    Measured: Week 1 (Pre-Assessment); Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  3. Change in Active Range of Motion (AROM)

    Lower extremity AROM will be measured using an electrogoniometer. This is a computerized device capable of measuring angles and giving an electronic output of the measurements. This device has been found to have high ratings of reliability and validity in the lower limb.

    Measured: Week 1 (Pre-Assessment); Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  4. 6 Minute Walk Test (6MWT) with COSMED K4B2 Metabolic unit

    The 6 minute walk test is performed as an objective evaluation of functional exercise capacity. The test measures the distance that the patient can walk on a flat, hard surface, indoors, in a period of 6 minutes. The walk test is patient self-paced and assesses the level of functional capacity. Patients are allowed to stop and rest during the test, however, the timer does not stop. If the patient is unable to complete the time, the time stopped is noted and reason for stopping prematurely is recorded. This test will be administered while wearing a mask to measure oxygen consumption. COSMED K4B2 (K4B2 COSMED, Italy) is a portable gas analysis system that measures oxygen consumption (VO2) and Carbon-dioxide production (VCO2 ) in a breath by breath fashion.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  5. Hill Assessment Index (HAI)

    The Hill Assessment Index is a 12 point ordinal scale used to assess different gait patterns during ascent or descent of slopes. It was developed to detect differences in function with different knee units for transfemoral prosthetics. Time and oxygen consumption will be measured during ramp ascent and descent. These activities will be performed while wearing a mask to measure oxygen consumption. This test takes under 5 minutes to complete.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  6. Stair Assessment Index (SAI)

    The Stair Assessment Index is a 14 point ordinal scale originally used to assess functional abilities during ascent and descent of stairs. Time and oxygen consumption will be measured during stair ascent and descent. These activities will be performed while wearing a mask to measure oxygen consumption. These tests take under 5 minutes to complete.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  7. Cross Walk Blinking Signal Test

    Time needed to cross a standard cross walk. The cross walk blinking signal test will measure how long it takes a participant to cross a designated street. The street that is designated for the test is 2 lanes and has ramps from the sidewalk to the street. The distance measured will be from the end of the ramp or edge of the curb on either side of the street. This distance is 36 feet. The literature recommends the cross walk velocity needed to safely cross is 0.9-1.2 m/s.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  8. GAITRite® Data Capture

    The GAITRite® system automates measuring temporal and spatial gait parameters via an electronic walkway connected to a computer. The GAITRite® electronic walkway contains sensor pads encapsulated in a carpet to collect gait information. The system can be laid over any flat surface. The GAITRite® electronic walkway for the study shall be a minimum of 14 feet long. The GAITRite® data capture was chosen as measurement of the patient's overall gait quality. Patients will be asked to walk at a self-selected speed and fast speed across the GAITRite® electronic walkway.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  9. 5 Times Sit to Stand Test (5XSST)

    The 5 Time Sit to Stand Test is a measure of functional lower limb strength during transitional movement. The individual sits in a standard height chair (43-45 cm) and is instructed to stand up and sit down 5 times as quickly as possible. The individual is not allowed to use upper extremities to push off and is instructed to cross arms over chest if able to do so. The test is scored by measuring the time it takes to complete the 5 stands. If the patient is unable to complete all 5 stands or requires assist greater than contact guard the test is scored as a fail.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  10. 4-Square Step Test

    Test of dynamic balance that clinically assesses the person's ability to step over objects forward, sideways and backwards. The test takes less than 5 minutes to administer and tests activity of daily living and motor skills.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  11. Talks While Walking Test (TWWT- Dual task test)

    The TWWT is used to determine the effects of cognitive attentional demands during walking by introducing a secondary thinking and talking task, while walking. Participants will perform the following tasks: timed walking up to 300 meters, performing a thinking and talking (numerical and/or vocabulary) task while sitting, and performing a thinking and talking task while walking (dual task) Participants voice will be recorded when performing all the thinking and talking tasks.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  12. Outdoor Uneven Surfaces Test

    This test will evaluate the participants gait characteristics and performance while walking on various surfaces that participants could encounter during activities of daily living. Participants will be asked to walk on typical outdoor uneven surfaces outside the entrance to the Rehabilitation Institute of Chicago (RIC), such as pavement, grass, uneven surfaces and ramps. Participants may use assistive device during this test. A researcher will walk with the participant to ensure safety and assist as needed.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  13. Amputee Mobility Predictor

    A tool used to predict the ambulatory potential of lower limb amputees, and measure function post-rehabilitation. It was developed to provide a more objective approach to rating amputees under the various K Classifications. The test can be performed with or without the prosthesis. The test involves activities of transfers, balance and walking. Score is out of 39 with each item scored in the range of 0-2

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

  14. Mini Mental State Exam (MMSE)

    Is a brief screening tool to provide a quantitative assessment of cognitive impairment and to record cognitive changes over time. The MMSE consists of 11 simple questions or tasks grouped into 7 cognitive domains. A possible score of 30 is used to provide a picture of an individual's present cognitive performance based on direct observation of completion of test items/tasks.

    Measured: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted2 Jul 2017
  2. Study startDec 2016
  3. Primary completionDec 2026 (estimated)
  4. Study completionDec 2026 (estimated)

Resources

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
Device feasibility
Allocation
Randomised
Intervention model
Crossover
Model description
Upon screening and enrollment participants return for up to 8 prosthetic fitting sessions and up to 12 physical therapy training sessions using their own microprocessor (MP) knee prosthesis and the powered knee-ankle (PKA) prosthesis. Once training is complete participants will return for up to 6 post-training assessment sessions per device. The device participants begin with will be randomly selected but there will be equal opportunity to train with both devices. In between training, there will be an 8 week "wash out period" to allow normalization to use of the device, reducing carryover effects. After wash-out period protocol will be repeated with second device.
Masking
None (open label)
Enrolment
15 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT03204513
Sponsor's protocol ID
STU00200842
Status last verified
Apr 2026
First submitted
22 Jun 2017
Last updated
22 Apr 2026
Results posted
No
Data monitoring committee
No
Individual data sharing
No

Publications

  • Embry KR, Jayaraman C, Yang C, Hoppe-Ludwig S, McGuire M, Mendley J, Mummidisetty CK, Lawson BE, Mohammadian K, Hunt J, Reddy A, Goldfarb M, Gordon KE, Jayaraman A. Beyond microprocessor knees: exploring the potential of fully powered prosthetic legs. J Neuroeng Rehabil. 2026 Jun 17. doi: 10.1186/s12984-026-02042-2. Online ahead of print.

    PubMed 42310747

Questions about this trial

What is this clinical trial studying?

A study testing Vanderbilt Powered Knee-Ankle Prosthesis and Microprocessor (MP) Knee Prosthesis in people with Transfemoral Amputees, run by Shirley Ryan AbilityLab 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 3 inclusion and 5 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: under way, not looking for participants, as of the sponsor's last update on 22 Apr 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?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change between devices of the Modified Graded Treadmill Test (time frame: Week 6-7 (Post-Training Assessments); Weeks 21-22 (Post-Training Assessment)). The study lists 2 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 NCT03204513, 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 22 Apr 2026.

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