Adaptive bone remodeling around bonded noncemented total hip arthroplasty: a comparison between animal experiments and computer simulation.

Severe loss of bone related to stress-shielding is one problem threatening the long-term integrity of noncemented total hip arthroplasty. It is widely accepted that this phenomenon is caused by adaptive bone remodeling according to Wolff's law. Recently, quantitative bone-remodeling theories have been proposed, suitable for use in computer-simulation models in combination with finite-element codes, which can be applied to simulate the long-term effect of the remodeling process. In the present paper, the results of such a computer simulation are compared with those in an animal experiment. A three-dimensional finite-element model was constructed from an animal experimental configuration concerning the implantation of a fully coated femoral hip prosthesis in dogs. The simulation results of the adaptive bone-remodeling process (geometric adaptations at the periosteal surface and density adaptations within the cancellous bone) were compared with cross-sectional measurements of the canine femurs after 2 years of follow-up. The detailed comparison showed that long-term changes in the morphology of bone around femoral components of total hip replacements can be fully explained with the present quantitative adaptive bone-remodeling theory.