Influence of Acetabular Cup Elevation Height on Contact and Failure Analysis of Metal-on-Metal Hip Prosthesis Under Mild and Severe Microseparations for Regular and Risky Gait Loads

Abstract

Abstract. Acetabular cup contact stress and failure analysis play a crucial role in estimating the durability of implants. Many studies have focused on the modification of acetabular cup design parameters to improve their longevity. The present study focuses on one such design consideration by varying the acetabular cup elevation height using a global model finite element conceptualization. Acetabular cup elevation height variation of 1, 2, and 3 mm with microseparations of 0.5, 1, 1.5, 2, 2.5, and 3 mm are considered to analyze contact and von Mises stress for the CoCr alloy at a 45 deg cup inclination angle. The peak gait loads of grouped gait activities, namely, A, B, C, and D, consisting of 19 gait loads, are used to estimate the aforesaid stresses. Group C and D gait load activities are very rarely performed by humans in day-to-day activities, while group A and B gait load activities are performed quite often by humans, except for a few gait activities like lifting and carrying loads. Results revealed that a cup elevation height of 3 mm was found to effectively reduce contact stress for microseparation of 2.5 and 3 mm. The 1 mm elevation height showed higher contact stress values for almost all microseparations. From von Mises plots, it is evident that the elevated acetabular cup prevents implant failure even for high microseparation values for gait loads grouped under the A and B categories. For physically demanding gait loads listed in group C and D categories, for all microseparation values, von Mises stress values of the elevated cup showed values higher than the yield stress of the CoCr alloy.