Vertebral endplate morphology follows bone remodeling principles

Study Design. A finite element model coupled with an iterative bone remodeling algorithm was used to optimize the morphology of the lumbar vertebrae. Objective. To theoretically predict the optimal vertebral density and thickness of the vertebral cortex and endplates. Summary of Background Data. Regional bone density variations have been reported. Both density and thickness of the endplate have been shown to increase toward the vertebral periphery. This study sought to address the possibility that the subchondral bone seeks an optimal morphology based on the principles of bone remodeling. Methods. An adaptive remodeling algorithm, driven by strain energy density, was applied to a previously validated 3D, nonlinear finite element model of an intact ligamentous L3-L5 segment. Both internal and external remodeling changes were considered. Results. The density of the vertebral cortex approached that of cortical bone, whereas the thickness of the anterior cortex exceeded that of the posterior shell and either endplate. The endplates thinned regionally over- and underlying the nucleus, increasing in thickness toward the periphery. Conclusion. The similarities between the models of the present investigation and various experimental reports indicate that the changes in the morphology of vertebral bone as the result of a mechanical adaptive process may be described via an adaptive bone remodeling theory.