Bretta L Fylstra1, I-Chieh Lee1, Stephanie Huang1, Andrea Brandt1, Michael D Lewek2, He Helen Huang3. 1. Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC 27606, USA. 2. Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. 3. Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC 27606, USA. Electronic address: hhuang11@ncsu.edu.
Abstract
BACKGROUND: Powered ankle-foot prostheses were developed to replicate the mechanics of the biological ankle by providing positive work during the push-off phase of gait. However, the benefits of powered prostheses on improving overall human gait efficiency (usually quantified by metabolic cost) have not been consistently shown. Here, we have focused on the mechanical work produced at the prosthetic ankle and its interaction with the amputee's movement. METHODS: Five unilateral transtibial amputees walked on a treadmill using 1) a powered ankle-foot prosthesis and 2) their daily passive device. We determined the net ankle work and ankle work loops on the prosthesis-side to quantify the efficiency of the human-prosthesis physical interaction. We further studied peak propulsion timing and the posture of the amputee's lower limb and prosthesis as indicators of the human-prosthesis coordination. Comparisons were made between the passive and powered prosthesis conditions for each participant. FINDINGS: The powered prosthesis did not consistently increase net ankle work compared to each participant's passive device. For participants that lacked efficiency in interacting with the powered prosthesis, we observed 1) early prosthesis-side peak propulsion timing (≥ 4% earlier) and 2) a more vertical residual shank at the time of peak propulsion (> 2° more vertical) indicating that the human's limb movement and the prosthesis control during push-off were not well coordinated. INTERPRETATION: Results from this preliminary study highlight the need for future work to systematically quantify the coordination between the human and powered prosthesis and understand how such coordination at the joint level influences overall gait efficiency.
BACKGROUND: Powered ankle-foot prostheses were developed to replicate the mechanics of the biological ankle by providing positive work during the push-off phase of gait. However, the benefits of powered prostheses on improving overall human gait efficiency (usually quantified by metabolic cost) have not been consistently shown. Here, we have focused on the mechanical work produced at the prosthetic ankle and its interaction with the amputee's movement. METHODS: Five unilateral transtibial amputees walked on a treadmill using 1) a powered ankle-foot prosthesis and 2) their daily passive device. We determined the net ankle work and ankle work loops on the prosthesis-side to quantify the efficiency of the human-prosthesis physical interaction. We further studied peak propulsion timing and the posture of the amputee's lower limb and prosthesis as indicators of the human-prosthesis coordination. Comparisons were made between the passive and powered prosthesis conditions for each participant. FINDINGS: The powered prosthesis did not consistently increase net ankle work compared to each participant's passive device. For participants that lacked efficiency in interacting with the powered prosthesis, we observed 1) early prosthesis-side peak propulsion timing (≥ 4% earlier) and 2) a more vertical residual shank at the time of peak propulsion (> 2° more vertical) indicating that the human's limb movement and the prosthesis control during push-off were not well coordinated. INTERPRETATION: Results from this preliminary study highlight the need for future work to systematically quantify the coordination between the human and powered prosthesis and understand how such coordination at the joint level influences overall gait efficiency.
Authors: Abbie E Ferris; Jennifer M Aldridge; Christopher A Rábago; Jason M Wilken Journal: Arch Phys Med Rehabil Date: 2012-06-22 Impact factor: 3.966
Authors: Joshua M Caputo; Evan Dvorak; Kate Shipley; Mary Ann Miknevich; Peter G Adamczyk; Steven H Collins Journal: J Prosthet Orthot Date: 2021-12-30