Design and analysis of polycentric prosthetic knee with enhanced kinematics and stability

Abstract

This paper describes a continuation of earlier work using the finite element method to conduct an engineering failure analysis of existing polycentric prosthetic knee. The primary purpose of this work is to enhance the quality of the existing knee which has been reported with multiple cases of failure during its clinical practice in India. A modified design of the polycentric knee has been proposed based on the findings of failure analysis. Simulation-based comparative analysis of polycentric knees has been performed as per the ISO 10328:2016 standard in terms of stress distribution, total contour deformation, safety factor, and fatigue life. The upper extension lever is subjected to static and cyclic loads of 4130 and 1230 N, whereas lower plate has translational constraint. The modified polycentric knee prosthesis outperforms static and fatigue strength tests. The standard of the existing knee prosthesis has significantly improved as a result of design variations and integration of high-strength and lightweight aluminium 7075-T6 alloy. The modified polycentric knee prosthesis has a predicted maximum deformation of less than 0.7 mm and a minimum safety factor between 1.7 and 2 compared to 2.66 mm and 1.0 for the existing knee prosthesis. Based on the fatigue simulation results, it is predicted that the modified polycentric knee will have a lifespan of at least ten years indicating a safe design. It has improved alignment stability and kinematics, with a significant weight reduction of 33 g, and a high cost-benefit ratio to reach the maximum amputee population in low-income countries like India.

The Mechanical Properties of the Lower Limb Socket Material Using Natural Fibers: A Review

“…In general, the design is divided into three classes according to the weight-bearing: patellar tendon bearing (PTB), total surface bearing (TSB), and hydrostatic loading. The socket can be manufactured in two ways [19][20][21][22][23][24]; the diagram below illustrates socket manufacturing methods, as shown in Fig. 3.…”

Design, Kinematics and Gait Analysis, of Prosthetic Knee Joints: A Systematic Review

“…Both passive and microprocessor-based prosthetic knees exhibit a rise in midstance and push-off work for the intact leg with increased walking speed, but this rise has no effect on the prosthetic limb. As a result, a prosthetic limb nearly completely loses energy and is dependent on the intact limb for energy changes [15]. The efficiency of healthy limbs may eventually be impacted by this additional effort.…”

Computational assessment of carbon fabric reinforced polymer made prosthetic knee: Mechanics, finite element simulations and experimental evaluation

“…Structural strength tests as per the International Organisation for Standardisation (ISO) 10328:2006 standards were performed by prior researchers 12,13 including static and fatigue analyses for a mechanical polycentric prosthetic knee by finite element simulations and experimentations to ensure its structural integrity. Mathematical models 14,15 were used to study the kinematics of the linkage mechanism used in polycentric knees to predict the relative motion between the links and trace the Instantaneous centre (I C ) of rotation for the designed linkage mechanism. Optimization algorithms 16,17 were also applied to evaluate and optimise the dimensions of the links and trajectory of I C to achieve natural gait.…”