Marisami P, Venkatachalam R
Department of Mechanical Engineering, Government Polytechnic College, Vanavasi, Salem, Tamil Nadu, India.
Department of Mechanical Engineering, KSR College of Engineering, Tiruchengode, Namakkal, Tamil Nadu, India.
Comput Methods Biomech Biomed Engin. 2022 May;25(6):656-667. doi: 10.1080/10255842.2021.1972291. Epub 2021 Sep 21.
Stability at the stance phase and near normal able-bodied swing phase kinematics are essential in designing the prosthetic knee mechanism for transfemoral amputees. Primarily, insufficient mid swing toe clearance results in asymmetrical gait patterns, leading to muscular-skeletal pain and joint degeneration. The present work is focused on synthesizing a polycentric knee mechanism to enhance the toe-clearance at mid-swing for safe level ground walking of amputees in developing countries. Both fixed and moving centrodes of the four-bar knee mechanism are considered in optimal synthesis of the mechanism for achieving able-bodied gait patterns using evolutionary algorithms in mechanism design software tools. The knee stability at heel contact, stabilizing moment at push-off, stable knee flexion range, maximum knee flexion and maximum toe-clearance at mid-swing are the parameters used for comparing the knee design with the existing commercially available designs. The optimized results are then verified experimentally by building a functional prototype using a 3 D printing technique. The designed mechanism executes nominal performance in four parameters and offers enhanced toe-clearance during mid-swing. This is a significant improvement over the existing designs for amputees to navigate comfortably on irregular terrain in developing countries.
对于经股骨截肢者的假肢膝关节机构设计而言，站立期的稳定性以及接近正常健全人摆动期的运动学特性至关重要。主要是，摆动中期脚趾离地间隙不足会导致步态模式不对称，进而引发肌肉骨骼疼痛和关节退变。目前的工作重点是合成一种多中心膝关节机构，以提高摆动中期的脚趾离地间隙，使发展中国家的截肢者能够在平坦地面安全行走。在机构设计软件工具中使用进化算法对四连杆膝关节机构进行优化合成时，考虑了该机构的固定瞬心线和活动瞬心线，以实现健全人的步态模式。足跟触地时的膝关节稳定性、蹬离时的稳定力矩、稳定的膝关节屈曲范围、最大膝关节屈曲度以及摆动中期的最大脚趾离地间隙是用于将该膝关节设计与现有的商用设计进行比较的参数。然后，通过使用3D打印技术制作功能原型对优化结果进行实验验证。所设计的机构在四个参数方面表现出标称性能，并在摆动中期提供了更大的脚趾离地间隙。这相对于现有的设计有显著改进，能让发展中国家的截肢者在不规则地形上更舒适地行走。
