# Do Transfemoral Prostheses with Powered Prosthetic Knee Flexion and Extension Improve Mobility? A Biomechanical Evaluation of the Ossur Power Knee > **NIH VA I01** · JESSE BROWN VA MEDICAL CENTER · 2024 · — ## Abstract 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 (1). The sagittal plane motion is used for progression in stance phase, and limb clearance and advancement in swing (2). 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 (6-9), 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, we believe that 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, we believe that the Ossur Power Knee may offer distinct advantages to female prosthesis users, so we intend to compare mobility 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. We hypothesize that 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. We hypothesize that subjects will have improved performance when using the Ossur Power Knee. Aim 3: To analyze and compare gender specific data... ## Key facts - **NIH application ID:** 10852182 - **Project number:** 1I01RX004541-01A2 - **Recipient organization:** JESSE BROWN VA MEDICAL CENTER - **Principal Investigator:** Steven A. Gard - **Activity code:** I01 (R01, R21, SBIR, etc.) - **Funding institute:** VA - **Fiscal year:** 2024 - **Award amount:** — - **Award type:** 1 - **Project period:** 2024-04-01 → 2027-03-31 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10852182 ## Citation > US National Institutes of Health, RePORTER application 10852182, Do Transfemoral Prostheses with Powered Prosthetic Knee Flexion and Extension Improve Mobility? A Biomechanical Evaluation of the Ossur Power Knee (1I01RX004541-01A2). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10852182. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*