Fatigue analysis of cemented hip prosthesis: model definition and damage evolution algorithms

This paper describes a work dedicated to the fatigue analysis of cemented total hip arthroplasty. In particular a quasi three-dimensional finite element model for fatigue analysis of the hip implant is initially developed. The side-plate concept is introduced to account for the three-dimensional structural integrity of the cement and cortical bone and to recover the hoop stress in the cement mantle as membrane stress. This is achieved by an appropriate calibration of the geometric parameters. Two different damage rules, linear and non-linear, are proposed to produce two different damage evolution algorithms. They are the so-called elasto-brittle and continuous damage algorithm, respectively. The elasto-brittle damage algorithm was shown to lead to conservative estimation of the fatigue lifetime. The continuous damage algorithm is then introduced and it will result in non-linear, anisotropic behaviour of the cement material after it is locally cracked. The corresponding fatigue lifetime estimation is shown to be closer to clinical evidence.