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Numerical Investigations of Stress Shielding in Total Hip Prostheses

Autoren:Behrens, B.-A.; Windhagen, H.; Wirth, C. J.; Nolte, I.; Bouguecha A.
Kategorie:Zeitschriften/Aufsätze (reviewed)
Jahr:2008
Veröffentlichung:Proceedings of the Institution of Mechanical Engineers, Part H, Journal of Engineering in Medicine, 222 (H5), pp. 593-600

Abstract

Aseptic loosening of the prosthesis is still a problem in artificial joint implants. The loosening can be caused by, among other factors, resorption of the bone surrounding the prosthesis due to stress shielding. In order to find out the influence of the prosthesis type on postoperative stress shielding, a static finite element analysis of a femur provided with the conventional uncemented stem BICONTACT and of one with the femoral neck prosthesis SPIRON was carried out. Strain energy densities and maximal principal strain distributions were calculated and compared to the physiological situation. Here, stress shielding was demonstrated in both periprosthetic femora.

To determinate the areas of the stress shielding, the bone in each FE-model was subdivided into three regions of interest (ROI): proximal, diaphyseal and distal. The numerical computations show stress shielding in the proximal ROI of both periprosthetic femora. Diaphyseally, the femoral neck prosthesis SPIRON, in contrast to the conventional uncemented long-stem one BICONTACT, causes no decrease in the strain distribution and thus no stress shielding. Distally, no change in the load distribution of either periprosthetic femur could be found, compared to the physiological situation.