Rogers-Bradley Emily, Yeon Seong Ho, Landis Christian, Lee Duncan R C, Herr Hugh M
K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, 02139, USA.
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, 02139, USA.
Sci Rep. 2024 Jul 17;14(1):16521. doi: 10.1038/s41598-024-67230-3.
Ankle push-off power plays an important role in healthy walking, contributing to center-of-mass acceleration, swing leg dynamics, and accounting for 45% of total leg power. The majority of existing passive energy storage and return prostheses for people with below-knee (transtibial) amputation are stiffer than the biological ankle, particularly at slower walking speeds. Additionally, passive devices provide insufficient levels of energy return and push-off power, negatively impacting biomechanics of gait. Here, we present a clinical study evaluating the kinematics and kinetics of walking with a microprocessor-controlled, variable-stiffness ankle-foot prosthesis (945 g) compared to a standard low-mass passive prosthesis (Ottobock Taleo, 463 g) with 7 study participants having unilateral transtibial amputation. By modulating prosthesis stiffness under computer control across walking speeds, we demonstrate that there exists a stiffness that increases prosthetic-side energy return, peak power, and center-of-mass push-off work, and decreases contralateral limb peak ground reaction force compared to the standard passive prosthesis across all evaluated walking speeds. We demonstrate a significant increase in center-of-mass push-off work of 26.1%, 26.2%, 29.6% and 29.9% at 0.75 m/s, 1.0 m/s, 1.25 m/s, and 1.5 m/s, respectively, and a significant decrease in contralateral limb ground reaction force of 3.1%, 3.9%, and 3.2% at 1.0 m/s, 1.25 m/s, and 1.5 m/s, respectively. This study demonstrates the potential for a quasi-passive microprocessor-controlled variable-stiffness prosthesis to increase push-off power and energy return during gait at a range of walking speeds compared to a passive device of a fixed stiffness.
踝关节蹬离功率在健康行走中起着重要作用，有助于质心加速、摆动腿动力学，且占腿部总功率的45%。现有的大多数用于膝下（经胫骨）截肢者的被动能量存储与回馈假肢比生物踝关节更硬，尤其是在步行速度较慢时。此外，被动装置提供的能量回馈水平和蹬离功率不足，对步态生物力学产生负面影响。在此，我们开展了一项临床研究，评估7名单侧经胫骨截肢患者使用微处理器控制的可变刚度踝足假肢（945克）与标准低质量被动假肢（奥托博克Taleo，463克）行走时的运动学和动力学。通过在计算机控制下跨步行速度调节假肢刚度，我们证明，与标准被动假肢相比，在所有评估的步行速度下，存在一种能增加假肢侧能量回馈、峰值功率和质心蹬离功，并降低对侧肢体峰值地面反作用力的刚度。我们证明，在0.75米/秒、1.0米/秒、1.25米/秒和1.5米/秒时，质心蹬离功分别显著增加26.1%、26.2%、29.6%和29.9%，在1.0米/秒、1.25米/秒和1.5米/秒时，对侧肢体地面反作用力分别显著降低3.1%、3.9%和3.2%。这项研究表明，与固定刚度的被动装置相比，准被动微处理器控制的可变刚度假肢在一系列步行速度下的步态中具有增加蹬离功率和能量回馈的潜力。
