Theoretical Model for Calculating the Rotation in Cementless Acetabular Cup Prosthesis Implanted by Press Fit into a Hip of Canines

Abstract

The aseptic loosening of the cementless acetabular cup prosthesis implanted by press fit into a hip is a fault caused by the application of an excessive load, which creates the rotation of the cup on the hip [1]. This rotation of the cup on the hip disables the prosthesis, and a new surgical intervention to place correctly the cup in the hip housing is required. The aseptic loosening of the cementless acetabular cup has been studied during decades mainly through experiments and numerical methods [2,3,4]. This paper shows the development of a theoretical model for calculating the maximum load that the cup of the prosthesis can support as well as the angle and direction of the net load. The model proposed is based on the hertz laws [5], which considers the interface between the cup and hip as two spheres between which there is a coefficient of static friction (μ), and is applied on a acetabular cups [6] implanted in artificial bone [7].