Transfemoral AmputationOPKTFANCT06218238
A Biomechanical Evaluation of the Ossur Power Knee in Persons With Transfemoral Amputation
A study testing Powered prosthetic knee joint in people with Transfemoral Amputation and Limb Loss, run by VA Office of Research and Development at 1 site in United States.
Trial summary
Microprocessor-controlled knees (MPKs) do not typically utilize motors to power joint rotation, but they automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the prosthesis user during gait. Read more about this study
- Who is it for?
- Ages 45 to 75 years
- Conditions the study is for
- Transfemoral Amputation, Limb Loss, Limb Absence
- What is being tested?
- Powered prosthetic knee joint
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Apr 2024to 31 Mar 2027
- 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 45 to 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Unilateral, transfemoral amputation (any etiology)
- Residual limb length classified as standard (i.e., medium) to long
- Prosthesis user for at least 1 year prior to enrolling in the study
- K3 or K4 level ambulator
- Good sensation on their residual limb(s) (upon routine clinical examination)
- Good skin integrity upon visual inspection
Show all 9Show fewer
- Does not require the use of assistive devices to walk for short distances
- Not currently taking medications that are known to affect balance or gait
- Presents with good socket fit based upon a standard assessment by the study prosthetist
Who cannot join
- Bilateral amputations
- Individuals with a knee disarticulation
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
Jesse Brown VA Medical Center, Chicago, IL
Chicago, Illinois, 60612
Rebecca Stine, MS, (312) 503-5726, rebecca.stine@va.gov
Steven A Gard, PhD, (312) 503-5718, steven.gard@va.gov
About this study
Official title: Do Transfemoral Prostheses With Powered Prosthetic Knee Flexion and Extension Improve Mobility? A Biomechanical Evaluation of the Ossur Power Knee
Microprocessor-controlled knees (MPKs) do not typically utilize motors to power joint rotation, but they automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the prosthesis user during gait. The Ossur Power Knee is the only commercially-available MPK that uses a motor to provide active power generation during walking and other activities. The purpose of this proposed investigation is to perform and compare biomechanical evaluations of the Power Knee and Ossur Rheo XC, a passive MPK, during walking and other activities by prosthesis users. Furthermore, mobility between male and female subjects will be compared to determine if there are differences in prosthetic knee usage on the basis of sex.
Read the detailed description
The anatomical knee is a complex, polycentric joint characterized by a large range of motion in the sagittal plane and limited mobility in the coronal and transverse planes. The sagittal plane motion is used for progression in stance phase, and limb clearance and advancement in swing. Limb prostheses are intended to restore function and cosmesis in persons with limb loss. The complexity and function of prosthetic components have advanced significantly as technology has improved, but a state-of-the-art artificial limb is still a relatively poor substitute for an anatomical one. Microprocessor-controlled knees (MPKs) do not typically utilize motors to power joint rotation, but they automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the user during gait. The Ossur Power Knee, which was first introduced in 2006, is the only MPK that uses a motor to provide active power generation during walking and other activities involving knee flexion and extension. Last year, Ossur released the 3rd generation of its Power Knee and appears to have addressed many of the previous shortcomings in terms of reduced weight, less noise, lower cost and longer battery life. Therefore, the newest version of the Power Knee warrants a fresh evaluation since it is, in essence, substantially different in design and function from previous models.
The purpose of this proposed investigation is to perform biomechanical evaluations of the new Ossur Power Knee during walking and other activities by transfemoral prosthesis users. Using a cross-over experimental design, approximately 20 unilateral, transfemoral amputee subjects (10 men and 10 women) will be evaluated in the Jesse Brown VAMC Motion Analysis Research Laboratory (MARL) while wearing the Ossur Power Knee and Ossur Rheo XC, which is a passive MPK device. Furthermore, the Ossur Power Knee may offer distinct advantages to female prosthesis users, so mobility will be compared between men and women to determine if differences exist on the basis of sex. The specific aims and hypotheses of this project are:
Aim 1: To compare the effects of the Ossur Power Knee and Ossur Rheo XC on the gait of unilateral, transfemoral prosthesis users during level walking. Kinematic and kinetic data will be collected as subjects walk in the MARL. Hypothesis--the active knee flexion and extension provided by the Ossur Power Knee will (1) improve walking performance, and (2) reduce metabolic energy cost during ambulation.
Aim 2: To compare the effects of the Ossur Power Knee and Ossur Rheo XC on stairs, slopes and during sit-to-stand/stand-to-sit activities of unilateral, transfemoral prosthesis users. Kinematic data will be collected as subjects perform these activities. Hypothesis--subjects will have improved performance when using the Ossur Power Knee.
Aim 3: To analyze and compare gender specific data between subjects using the Ossur Power Knee and the Ossur Rheo XC. Hypothesis--male and female subjects will demonstrate substantially different abilities to use the two knee components, indicating that gender specific components should be further investigated and developed. Research focusing on the unique prosthetic needs of women Veterans is currently a special emphasis area of the VA RR\&D Service.
Subjects will also be administered questionnaires and provided at-home diaries to document their perceptions of comfort, exertion and stability while using the different prosthetic knee units.
The repeated-measures, cross-over protocol design enables each subject to serve as their own control, and it will be determined whether statistically significant changes occur in their performance measures. A two-way mixed-methods ANOVA will be used to assess the main and interaction effects of sex (male, female) and knee type (Ossur Power Knee, Rheo XC). As a conservative approach, a Bonferroni correction will be used to account for the family-wise Type I error rate because multiple outcomes will be used to address each hypothesis.
Increased understanding about how the Ossur Power Knee affects the abilities of transfemoral prosthesis users will facilitate appropriate component selection by prosthetists and ultimately improve quality of life for prosthesis users.
- Conditions
- Transfemoral Amputation, Limb Loss, Limb Absence
- Being tested
- Powered prosthetic knee joint, Conventional microprocessor-controlled prosthetic knee joint
- Keywords
- amputation, limb loss, limb deficiency, transfemoral, above-knee, prosthesis, knee joint
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Powered prosthetic knee jointOther
Also called Ossur Power Knee
Subjects will be fitted and trained on the Ossur Power Knee. An accommodation of 1 month will be provided prior to evaluation with the knee joint.
Conventional microprocessor-controlled prosthetic knee jointOther
Also called Ossur Rheo
Subjects will be fitted and trained on the Ossur Rheo XC Knee. An accommodation of 1 month will be provided prior to evaluation with the knee joint.
| Study group | Role | What they receive |
|---|---|---|
| Ossur Power Knee | Experimental | Subjects will be fitted with the Ossur Power Knee, which has powered flexion and extension. Receives: Other: Powered prosthetic knee joint |
| Ossur Rheo XC Knee | Active comparator | Subjects will be fitted with the Ossur Rheo XC Knee, which is a conventional microprocessor-controlled prosthetic knee joint that modulates the amount of damping during flexion and extension. Receives: Other: Conventional microprocessor-controlled prosthetic knee joint |
What is being measured
The primary outcome is the main question the study is designed to answer.
Walking speed
Walking speed will be measured as participants walk on level ground at slow, normal and fast speeds.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Metabolic energy cost
The metabolic energy rate will be measured as subjects walk at their freely selected speed on a level treadmill, which will be converted to metabolic energy cost (energy expended per unit distance).
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Sit-to-stand/stand-to-sit symmetry
Knee kinematics and load distribution between the sound and prosthetic sides will be measured as participants stand up and sit down in a chair.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Secondary outcomes (4)
Step length
The step lengths of the sound and prosthetic sides will be measured as participants walk on level ground at slow, normal and fast speeds.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Toe clearance during swing phase
Toe clearance during swing phase on the prosthetic side will be measured as participants walk on level ground at slow, normal and fast speeds.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Sound leg loading rate
The sound leg loading rate during walking will be measured as participants walk on level ground at slow, normal and fast speeds.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Kinematics of pelvic motion
Pelvic tilt, rotation and obliquity will be measured as participants walk on level ground at slow, normal and fast speeds.
Measured: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jan 2024
- Study start1 Apr 2024
- Primary completion31 Jan 2027 (estimated)
- Study completion31 Mar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Transfemoral AmputationStudies of the same condition, open and under way.
- More trials run by VA Office of Research and DevelopmentThe 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Using a cross-over experimental design, 20 unilateral, transfemoral amputee subjects (10 men and 10 women) will be evaluated in the Jesse Brown VAMC Motion Analysis Research Laboratory (MARL) while wearing the Ossur Power Knee and Ossur Rheo XC. Subjects will be provided a one-month accommodation period wearing each prosthetic knee prior to testing. Prosthetic foot type will be standardized for subjects so they will walk with the same foot while testing each prosthetic knee joint.
- Masking
- None (open label)
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- VA Office of Research and Development
- Sponsor type
- US federal agency
- Responsible party
- Sponsor
- Investigators
- Steven A Gard, PhD, Principal investigator, Jesse Brown VA Medical Center, Chicago, IL
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06218238
- Sponsor's protocol ID
- A4541-R
- Other IDs
- 5I01RX004541-02, RX004541-01A2
- Acronym
- OPKTFA
- Status last verified
- Sep 2026
- First submitted
- 11 Jan 2024
- Last updated
- 22 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: A Limited Dataset (LDS) will be created and shared pursuant to a Data Use Agreement (DUA) appropriately limiting use of the dataset and prohibiting the recipient from identifying or re-identifying (or taking steps to identify or re-identify) any individual whose data are included in the dataset. Results from this study will be freely disseminated via presentations at professional conferences and publications in scientific journals. Additionally, data acquired for this project will be shared with those investigators who make a formal request to the PI and can demonstrate a legitimate and justifiable cause for utilization of such data. All requests for these data will be discussed with the VA scientific program manager.
Study at a glance
From the registry record, last updated by the sponsor on 22 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Do Transfemoral Prostheses With Powered Prosthetic Knee Flexion and Extension Improve Mobility? A Biomechanical Evaluation of the Ossur Power Knee
- ClinicalTrials.gov ID
- NCT06218238
- Acronym / sponsor ID
- OPKTFA / A4541-R
- Conditions
- Transfemoral Amputation, Limb Loss, Limb Absence
- Keywords
- amputation, limb loss, limb deficiency, transfemoral, above-knee, prosthesis, knee joint
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 20 participants (estimated)
- Lead sponsor
- VA Office of Research and DevelopmentUS federal agency
- Study start
- 1 Apr 2024 (actual)
- Primary completion
- 31 Jan 2027 (estimated)
- Study completion
- 31 Mar 2027 (estimated)
- First posted
- 23 Jan 2024 (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.
Microprocessor-controlled knees (MPKs) do not typically utilize motors to power joint rotation, but they automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the prosthesis user during gait. The Ossur Power Knee is the only commercially-available MPK that uses a motor to provide active power generation during walking and other activities. The purpose of this proposed investigation is to perform and compare biomechanical evaluations of the Power Knee and Ossur Rheo XC, a passive MPK, during walking and other activities by prosthesis users. Furthermore, mobility between male and female subjects will be compared to determine if there are differences in prosthetic knee usage on the basis of sex.
Detailed description
The anatomical knee is a complex, polycentric joint characterized by a large range of motion in the sagittal plane and limited mobility in the coronal and transverse planes. The sagittal plane motion is used for progression in stance phase, and limb clearance and advancement in swing. Limb prostheses are intended to restore function and cosmesis in persons with limb loss. The complexity and function of prosthetic components have advanced significantly as technology has improved, but a state-of-the-art artificial limb is still a relatively poor substitute for an anatomical one. Microprocessor-controlled knees (MPKs) do not typically utilize motors to power joint rotation, but they automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the user during gait. The Ossur Power Knee, which was first introduced in 2006, is the only MPK that uses a motor to provide active power generation during walking and other activities involving knee flexion and extension. Last year, Ossur released the 3rd generation of its Power Knee and appears to have addressed many of the previous shortcomings in terms of reduced weight, less noise, lower cost and longer battery life. Therefore, the newest version of the Power Knee warrants a fresh evaluation since it is, in essence, substantially different in design and function from previous models.
The purpose of this proposed investigation is to perform biomechanical evaluations of the new Ossur Power Knee during walking and other activities by transfemoral prosthesis users. Using a cross-over experimental design, approximately 20 unilateral, transfemoral amputee subjects (10 men and 10 women) will be evaluated in the Jesse Brown VAMC Motion Analysis Research Laboratory (MARL) while wearing the Ossur Power Knee and Ossur Rheo XC, which is a passive MPK device. Furthermore, the Ossur Power Knee may offer distinct advantages to female prosthesis users, so mobility will be compared between men and women to determine if differences exist on the basis of sex. The specific aims and hypotheses of this project are:
Aim 1: To compare the effects of the Ossur Power Knee and Ossur Rheo XC on the gait of unilateral, transfemoral prosthesis users during level walking. Kinematic and kinetic data will be collected as subjects walk in the MARL. Hypothesis--the active knee flexion and extension provided by the Ossur Power Knee will (1) improve walking performance, and (2) reduce metabolic energy cost during ambulation.
Aim 2: To compare the effects of the Ossur Power Knee and Ossur Rheo XC on stairs, slopes and during sit-to-stand/stand-to-sit activities of unilateral, transfemoral prosthesis users. Kinematic data will be collected as subjects perform these activities. Hypothesis--subjects will have improved performance when using the Ossur Power Knee.
Aim 3: To analyze and compare gender specific data between subjects using the Ossur Power Knee and the Ossur Rheo XC. Hypothesis--male and female subjects will demonstrate substantially different abilities to use the two knee components, indicating that gender specific components should be further investigated and developed. Research focusing on the unique prosthetic needs of women Veterans is currently a special emphasis area of the VA RR\&D Service.
Subjects will also be administered questionnaires and provided at-home diaries to document their perceptions of comfort, exertion and stability while using the different prosthetic knee units.
The repeated-measures, cross-over protocol design enables each subject to serve as their own control, and it will be determined whether statistically significant changes occur in their performance measures. A two-way mixed-methods ANOVA will be used to assess the main and interaction effects of sex (male, female) and knee type (Ossur Power Knee, Rheo XC). As a conservative approach, a Bonferroni correction will be used to account for the family-wise Type I error rate because multiple outcomes will be used to address each hypothesis.
Increased understanding about how the Ossur Power Knee affects the abilities of transfemoral prosthesis users will facilitate appropriate component selection by prosthetists and ultimately improve quality of life for prosthesis users.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Using a cross-over experimental design, 20 unilateral, transfemoral amputee subjects (10 men and 10 women) will be evaluated in the Jesse Brown VAMC Motion Analysis Research Laboratory (MARL) while wearing the Ossur Power Knee and Ossur Rheo XC. Subjects will be provided a one-month accommodation period wearing each prosthetic knee prior to testing. Prosthetic foot type will be standardized for subjects so they will walk with the same foot while testing each prosthetic knee joint.
| Arm | Type | Receives |
|---|---|---|
| Ossur Power Knee | Experimental | Other: Powered prosthetic knee jointSubjects will be fitted with the Ossur Power Knee, which has powered flexion and extension. |
| Ossur Rheo XC Knee | Active comparator | Other: Conventional microprocessor-controlled prosthetic knee jointSubjects will be fitted with the Ossur Rheo XC Knee, which is a conventional microprocessor-controlled prosthetic knee joint that modulates the amount of damping during flexion and extension. |
Who may qualify
- Ages
- 45 to 75 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (9 listed)
- Unilateral, transfemoral amputation (any etiology)
- Residual limb length classified as standard (i.e., medium) to long
- Prosthesis user for at least 1 year prior to enrolling in the study
- K3 or K4 level ambulator
- Good sensation on their residual limb(s) (upon routine clinical examination)
Key exclusion criteria (2 listed)
- Bilateral amputations
- Individuals with a knee disarticulation
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 prosthetic knee jointAlso: Ossur Power KneeSubjects will be fitted and trained on the Ossur Power Knee. An accommodation of 1 month will be provided prior to evaluation with the knee joint. | Other | Ossur Power Knee |
| Conventional microprocessor-controlled prosthetic knee jointAlso: Ossur RheoSubjects will be fitted and trained on the Ossur Rheo XC Knee. An accommodation of 1 month will be provided prior to evaluation with the knee joint. | Other | Ossur Rheo XC Knee |
Primary outcome
Walking speed
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Walking speed will be measured as participants walk on level ground at slow, normal and fast speeds.
Metabolic energy cost
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
The metabolic energy rate will be measured as subjects walk at their freely selected speed on a level treadmill, which will be converted to metabolic energy cost (energy expended per unit distance).
Sit-to-stand/stand-to-sit symmetry
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Knee kinematics and load distribution between the sound and prosthetic sides will be measured as participants stand up and sit down in a chair.
4 secondary outcomes
Step length
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Toe clearance during swing phase
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Sound leg loading rate
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
Kinematics of pelvic motion
Time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component
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 22 Sep 2026.
- Individual participant dataSharing planned: No. A Limited Dataset (LDS) will be created and shared pursuant to a Data Use Agreement (DUA) appropriately limiting use of the dataset and prohibiting the recipient from identifying or re-identifying (or taking steps to identify or re-identify) any individual whose data are included in the dataset. Results from this study will be freely disseminated via presentations at professional conferences and publications in scientific journals. Additionally, data acquired for this project will be shared with those investigators who make a formal request to the PI and can demonstrate a legitimate and justifiable cause for utilization of such data. All requests for these data will be discussed with the VA scientific program manager.
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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.
Steven A Gard, PhD principal investigator
Jesse Brown VA Medical Center, Chicago, IL
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 prosthetic knee joint in people with Transfemoral Amputation and Limb Loss, run by VA Office of Research and Development 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 9 inclusion and 2 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 22 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 Rebecca Stine, MS ((312) 503-5726, rebecca.stine@va.gov), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Walking speed (time frame: To be measured after the 1-month accommodation period of wearing each prosthetic knee component). 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?
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 Sep 2026.