COMPOSITE HIP-PROSTHESIS DESIGN .2. SIMULATION

An investigation was performed to study the mechanical performance of fiber-reinforced composite hip prostheses. In Part I of the study, a t hree-dimensional finite element code was developed for analyzing a com posite hip prosthesis in a femur. The material properties of the compo site were treated as anisotropic and inhomogeneous while the propertie s of the femoral bone were treated as anisotropic and homogeneous. All the materials were assumed to behave linear-elastically. Thermoplasti c graphite/PEEK material was selected for the study. No slippage was a ssumed at the interface between the implant and the surrounding femora l bone. In Part Il, numerical simulations were performed using the cod e to study the performance of a composite prosthesis in the femur. The stress/strain distributions, micromotions, and strain energy density of the surrounding femoral bone were evaluated and found to be related to initial fixation and long-term stability of the prosthesis in the femur. Numerous fiber orientations were studied, and the results of th e calculations were compared with those generated from a prosthesis ma de of cobalt chrome and Ti-6Al-4V titanium alloys. Based on the analys is, it was shown that compared to conventional metallic implants more favorable stresses and deformations could be generated in the femur us ing composite implants. In addition, by changing fiber orientations ac cording to femoral loads, a composite implant could be designed specif ically for the left or the right femur. (C) 1998 John Wiley & Sons, In c.