NCT06218238 · VA Office of Research and Development
A Biomechanical Evaluation of the Ossur Power Knee in Persons With Transfemoral Amputation
(OPKTFA)
What this study is about
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.
View original scientific description
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.
Interventions
OTHER
Powered prosthetic knee joint
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.
OTHER
Conventional prosthetic knee joint
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.
Primary outcome measures
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Unilateral, transfemoral amputation (any etiology).
- Age from 45-75 years.
- 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.
- 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.
Exclusion criteria
- Bilateral amputations
- Individuals with a knee disarticulation
Where
- Chicago, Illinois
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
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Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
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Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
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How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Sep 9, 2025 · Source of record for eligibility and locations