Due to the commercial launch of newly developed ceramic-on-metal (COM) bearings, we compared the deformation and stresses in the liner with ceramic-on-ceramic (COC), metal-on-metal (MOM) as well as ceramic-on-polyethylene (COP) bearings using a finite-element (FE)-model, analyzing a variety of head size and implant position. Liner deformation in terms of change in inner diameter as well as peak stresses were evaluated. The FE-model consisting of a commercial THR, the proximal femur and a section of the hemipelvis was created based on our previously published approach. Static load and muscle forces were applied according to the maximum load during gait. Polyethylene was modelled using a nonlinear definition with isotropic hardening, cobalt-chromium was modelled elastic-plastic and ceramic was modelled linear-elastic. Validity of the model was checked using an experimental setup with artificial bone and strain gauges located at the rim of the liner. Implant material (COM vs. COC vs. MOM vs. COP), head size (28 mm vs. 36 mm) and cup position (45° inclination/15° anteversion vs. 60° incl./0° antev.) were varied.Introduction
Methods
