Study and evaluation of four bar polycentric knee used in the prosthetic limb for transfemoral amputee during the gait cycle

Abstract

The prosthetic knee is one of the most important parts used in manufacturing of the above knee prostheses limb and it is considered the most important component. Accordingly, it became necessary to conduct a study and evaluate for different types a prosthetic knee. In present work, the mechanism of four bar 3R20 prosthetic knee were evaluated and studied. Virtual model of four bar 3R20 prosthetic knee joint was built using Solid Work 2018 program. The fifty parts of four bar polycentric knee were designed separately and then assembled together. The kinematic analysis of four bar polycentric knee was performed using geometric analysis and Grashof law for double rocket. The results of instant center of rotation (ICR) from analytical solution was estimated using MATLAB program. The kinetic model include data of two components of forces and joint moments which used for transfemoral amputee with (age, height, weight, and stump length) of (28 years, 178 cm, 78 kg, and 29 cm) respectively. The numerical analysis of four bar prosthetic knee involved select the element type in ANSYS Workbench 19.2 program. Quadrilateral and trihedral elements were used in the finite element analysis to generate the mesh. The static analysis was investigated during different segmentation of gait cycle. The results of equivalent (von Mises) stress distribution calculated during stance phase for different loading conditions showed that the maximum stress was printed at the loading response phase with 226.93 Mpa at the root region between prosthetic knee and socket when orientation angles θ 2 = 85.5° and θ 4 = 105.4° and ICR coordinates are −0.560 mm and 77.388 mm for X,Y respectively.