A Biomechanical Evaluation of the Ossur Power Knee in Persons With Transfemoral Amputation

NCT06218238 | Recruiting

• 2 other identifiers: A4541-RRX004541-01A2
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Transfemoral Amputation; Limb Loss; Limb Absence

Keywords

amputation; limb loss; limb deficiency; transfemoral; above-knee; prosthesis; knee joint

Outcome Measures

Primary Outcomes (3)

• Walking speed

  Walking speed will be measured as participants walk on level ground at slow, normal and fast speeds.

  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).

  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.

  To be measured after the 1-month accommodation period of wearing each prosthetic knee component

Secondary Outcomes (4)

• Step length

  To be measured after the 1-month accommodation period of wearing each prosthetic knee component

• Toe clearance during swing phase

  To be measured after the 1-month accommodation period of wearing each prosthetic knee component

• Sound leg loading rate

  To be measured after the 1-month accommodation period of wearing each prosthetic knee component

• Kinematics of pelvic motion

  To be measured after the 1-month accommodation period of wearing each prosthetic knee component

Study Arms (2)

Ossur Power Knee

EXPERIMENTAL

Subjects will be fitted with the Ossur Power Knee, which has powered flexion and extension.

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 knee joint that modulates the amount of damping during flexion and extension.

Other: Conventional prosthetic knee joint

Interventions

Powered prosthetic knee joint OTHER

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.

Ossur Power Knee

Conventional prosthetic knee joint OTHER

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.

Ossur Rheo XC Knee

Eligibility Criteria

• Age: 45 Years - 75 Years
• Gender Eligibility Details: A total of 10 males and 10 females will be enrolled in this study. Subjects must meet the inclusion/exclusion criteria listed previously.
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• Bilateral amputations
• Individuals with a knee disarticulation

Sponsors & Collaborators

• VA Office of Research and Development: lead

Study Sites (1)

Jesse Brown VA Medical Center, Chicago, IL

Chicago, Illinois, 60612, United States

RECRUITING

Study Officials

• Steven A Gard, PhD

  Jesse Brown VA Medical Center, Chicago, IL

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Rebecca Stine, MS

CONTACT

(312) 503-5726; rebecca.stine@va.gov

Steven A Gard, PhD

CONTACT

steven.gard@va.gov

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: FED
• Responsible Party: SPONSOR

Model Details: 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.

Study Record Dates

• First Submitted: January 11, 2024
• First Posted: January 23, 2024
• Study Start: April 1, 2024
• Primary Completion (Estimated): January 31, 2027
• Study Completion (Estimated): March 31, 2027
• Last Updated: September 9, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)