Computational Muscle Driven Knee Simulator for Assessment of Total Knee Replacement Post-Cam Mechanics

Mohd Afzan Mohd Anuar,Mitsugu Todo

doi:10.14419/ijet.v7i4.27.22509

Abstract

Biomechanics of post-cam mechanism is essential in determining the longevity of knee implant. Computational knee simulator is an efficient method in characterizing TKA performance under various boundary conditions. The existing knee simulators, however, were actuated only by quadriceps translation and hip load to perform squatting motion. The present computational knee simulator was developed based on lower limb of Japanese female subject having body weight, W = 51 kg and height, H = 148 cm. Two different designs of PS-type knee prostheses were tested namely Superflex and NRG. The knee motion was driven by three major muscles; quadriceps, hamstrings and gastrocnemius. The biomechanical behavior of tibiofemoral articulation associated with post-cam engagement mechanics was observed. Post-cam engagement occurred at 80° and 65° of flexion angles for Superflex and NRG, respectively. Maximum von Mises stresses at tibial post were 80 MPa and 50 MPa for Superflex and NRG, respectively. The developed computational muscle driven knee simulator has successfully assessed the performance of TKA prostheses.

Highlights

Introduced in the last four decades, posterior-stabilized (PS) total knee replacement (TKR) procedure was designed to substitute Posterior cruciate ligament (PCL) function in governing anterior-posterior (AP) translation and allowing femoral rollback [1]
PS-TKR knee implant is commonly designed to have a tibial spine and femoral cam that interact at certain flexion angle as the knee bends
The biomechanics of the post-cam mechanism are important in determining the longevity of knee implant that partly involve tibial post failure, and post-operative knee kinematics associated with the range of motion (ROM), AP translation and tibial rotation [2]–[3]

Summary

Introduction

Introduced in the last four decades, posterior-stabilized (PS) TKR procedure was designed to substitute PCL function in governing anterior-posterior (AP) translation and allowing femoral rollback [1]. PS-TKR knee implant is commonly designed to have a tibial spine and femoral cam that interact at certain flexion angle as the knee bends. Most studies assessed the effect of post-cam design on tibiofemoral contact mechanics, tibial post internal stress and kinematics of implanted knee. Some researchers performed contact analysis on knee implant using in vitro testing devices They measured contact areas and contact stress of various designs at different tibial and flexion angles using stress sensor [4]-[5]. Numerous studies on tibiofemoral kinematics were done commonly involved in vivo fluoroscopic analysis [3], [8]-[9] These studies used static (or quasi-static) approaches by investigating a limited number of static positions of tibiofemoral joint during flexion

Methods

Results

Conclusion