Contact Stress and Wear Analysis of Zirconia Against Alumina for Normal and Physically Demanding Loads in Hip Prosthesis

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Journal of Bionic Engineering http://www.springer.com/journal/42235

Contact Stress and Wear Analysis of Zirconia Against Alumina for Normal and Physically Demanding Loads in Hip Prosthesis Subramaniam Shankar1*, Rajavel Nithyaprakash1, Palanisamy Sugunesh2, Mohammad Uddin3, Alokesh Pramanik4 1. Department of Mechatronics Engineering, Kongu Engineering College, Erode, TamilNadu, India 2. Department of Mechanical Engineering, Kongu Engineering College, Erode, TamilNadu, India 3. University of South Australia, UniSA STEM, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia 4. School of Civil and Mechanical Engineering, Curtin University, Bentley, WA, Australia

Abstract Risky gait activities lead to severe wear in orthopaedic implants during postoperative periods. The aim of the present study is to predict the linear and volumetric wear of zirconia (ZrO2) vs alumina (Al2O3) hip implants subject to risky and normal gait activities. Initially, the gait loads pertaining to risky gait activities were converted to equivalent normal loads. Then using the computed normal loads, friction and wear coefficients of ZrO2 ball against Al2O3 disc were calculated from Pin-on-Disc (POD) tribometer under dry and lubricating conditions. Saline solution, a bio-lubricant was utilized for lubrication purpose to mimic synovial fluid properties. Nineteen gait activities stair ascending or descending, carrying load, lifting load and ladder up or down etc., grouped as A, B, C and D were used to determine friction and wear coefficients. Finite Element Method (FEM) was employed to predict the wear of the bearing couple. The developed contact pressure for these gait activities was then utilized to compute linear and volumetric wear for 2 million cycles. Our findings suggests that, patients regularly involved in group C and D type gait activities were likely to cause more wear which may accelerate early implant failure. Keywords: hip implants, gait activities, pin-on-disc, lubrication, FEM, wear Copyright © Jilin University 2020.

1 Introduction Hip resurfacing arthroplasty involves in replacement of femur head and acetabulum cup using biocompatible materials such as metal, ceramic and polyethylene. Wear in the bearing surfaces is found to be the major cause for implant failures. Due to the kinematics and dynamic nature of implants, wear is primarily caused by regular gait activity such as walking. However, less frequent yet physically risky gait activities such as stair ascending-descending and carrying-transferring a payload can accelerate wear-induced failures. Research shows that wear related damage to implants is higher if patients are frequently involved in stair climbing activity[1]. Higher hip joint contact forces are observed for gait activity associated with carrying and transferring load as compared to normal walking[2]. In literature, the impact of these are less common but quite intensive gait activities on potential implant failures has not been stu*Corresponding author: Subramaniam Shankar E-mail: [email protected]

died well.