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Durham University

Department of Engineering

Staff Profile

Publication details for Professor Jun Jie Wu

Wang, Q. Q. & Wu, J. J. (2009), Numerical Prediction on Mechanical Contacts Vanguard Knee Joint replacements Tested in the Displacement-Controlled Prosim Simulator, IMeChE Knee Arthroplasty: From Early Intervention to Revision. London, Institution of Mechanical Engineers, 289-292.

Author(s) from Durham

Abstract

Exploring the mechanical environments in total knee replacements (TKR) has been indentified to be useful to understand the early failure of the prostheses. The severe damages observed on the retrieved polyethylene tibial component implicate that the materials may undertake the excessive stresses and strains. As an alternative way to measure the stresses in vitro, the computational simulation technique has been developed and widely used to make the predictions pre-clinically.
The present work addressed the contact conditions in a cruciate ligament retaining type knee joint - Vanguard (Biomet). The schematics and meshes generated were shown in Figure 1. The finite element model was analyzed in ABAQUS/Standard at seventeen temporal instances, which were mainly at the peaks or valleys of the profiles (in Figure 2). The input data for the load, displacements and rotations were obtained from the gait analysis in ISO standard and the paper related (Lafortune et al., 1992; Barnett et al., 2002; BS ISO 14243-3: 2004). The loading and constraint conditions employed were derived from the displacement-controlled ProSim knee simulator, in which the tibial insert swung like a pendulum during wear testing and was free in the varus-valgus rotation. Also the compressive load was applied offset toward the medial condyle to produce the 60% to 40% load split. The polyethylene insert was assumed to be elasto-plastic material, which had the linear elastic modulus of 600MPa and the yield stress of 10.8MPa.