Experimental and computational wear studies of silicon nitride against ceramic and metallic biomaterials for human hip prosthesis

Abstract

Due to aging as well as physically demanding activities, humans undergo artificial hip implantation involving replacement of acetabulum cup and femur head. Wear of the bearing is a major problem in hip implants forcing the patients to undergo revision surgery. Hip simulator, pin-ondisc/ ball-on-disc and finite element analysis (FEA) are widely used approaches to estimate wear. While former two are shown to be widely newlineemployed for wear prediction in both lubricated and non-lubricated conditions, they are often not suitable for assessing wear in the event of extensive change of hip design parameters. The design parameters mainly influencing wear include radial clearance, edge loading, acetabulum cup thickness, femur head diameter and cup inclination angle etc. In this work, experimental and computational approaches are involved in predicting tribological behavior of silicon nitride (Si3N4) ceramic against alumina (Al2O3), Zirconia (ZrO2) and Titanium alloy Ti6Al4V (grade 5) biomaterial combinations. Initially, ZrO2 pin biomaterial was used to estimate the friction and wear coefficient for 60 km run under dry and saline solution bio-lubricant against Al2O3 disc. Later a global model finite element approach was used to estimate the wear of bearings for 20 million cycles. Linear as well as volumetric wear were estimated with the help of contact newlinepressure obtained from finite element (FE) model. Due to non-uniformity in contact of pin with disc, later zirconia ball material was used to estimate the friction and wear coefficient for normal and physically demanding gait activities. newline newline