Analysis of Four-bar Linkages Suitable for Above-knee Prosthesis

Abstract

Four-bar linkage above-knee prosthesis provide a greater toe clearance in the swing phase and stability in the stance phase in comparison to the single-axis knee joint. Just because of its simplicity, the four-bar linkage is still the most commonly preferred mechanism because it permits the prosthesis to be sufficiently stable and replicates the natural movement of the joint. The authors present a basic/simple kinematic model using a four-bar knee prosthesis. In all eight different configurations are evaluated and examined using a program with the use of the arrangement. These configurations of the four-bar linkage mechanism will enable the prosthetist to assess the mechanical advantage of different four-bar designs. Also, plots of the angle of flexion vs. increase of toe clearance of these eight configurations is provided to enable comparative advantage for the user. It was noticed that the entire length of the prosthesis gets shortened while moving from the extension to the flexion phase. This aspect minimizes energy consumption during the initial phase of motion. All configurations of four-bar knee linkages have been examined and the results show that they have nearly the same energy conservation.