THE ADAPTATION OF BONE APPARENT DENSITY TO APPLIED LOAD

A phenomenological theory of bone remodeling was developed with improv ed spatial stability compared to some of the more standard formulation s. The improved stability was created by changing the nature of the re modeling differential equation to have an exponential character. As a result, the theoretical predictions are consistent with the experiment al observation that changes in bone density during disuse, after hip s urgery, during growth and during aging are all consistent with an expo nential dependence of density on time. The new theory and the standard theory were both used to model the time course of bone changes in two animal models of bone loss during disuse. The new theory was better a ble to model the results of the experiments than the standard theory. The basic continuum theory underlying the remodeling theory was presen ted in some detail. This presentation was used to motivate the develop ment of the new theory, as the standard theories can predict non-smoot h distributions of bone density rather than the expected smooth distri butions. it was shown that these non-smooth distributions are a violat ion of the continuum assumption, one of the bases for the theory of fi nite element stress analysis. The new model's stability was investigat ed using example problems and shown to be improved compared to the sta ndard model.