Stiffness and Eigenfrequencies of Press-Fit Acetabular Shell Designs

INTRODUCTION: Squeaking of hard-on-hard hip joint bearings has recently become a concern in modern total hip arthroplasty due to its high impact on the quality of life of the patient [1]. Many factors such as malpositioning of implant play a role in the arisal of this phenomenon [2]. The probability of the excitation of audible vibrations is also related to prosthesis design [3]. In particular the first eigenfrequencies of the acetabular shell might play a major role for the susceptibility of a design to squeaking. The purpose of this study was to investigate the stiffness and eigenfrequencies of different shell designs and to verify the theoretically assumed relationship between these variables.