How screw connections influence the primary stability of acetabular cups under consideration of different bone models.

INTRODUCTION: Good osteointegration of implants requires sufficient primary stability. Aim of this study was to examine the influence of screw fixation on the primary stability of press-fit cups. METHODS: Two press-fit acetabular cups were tested with regard to the influence and number of screws and their primary stability. RESULTS: For the relatively thin-walled Allofit®-S cup, an influence of the number of screws on the different forms of movement could be demonstrated. CONCLUSIONS: We see a clear influence of the cup wall thickness on the elastic deformability and accordingly on the primary stability of the examined cups.