Evaluation of osteoporotic bone quality by a computational model for bone remodeling

This paper presents a study to evaluate the capacity of bone remodeling computational models to assess bone quality in presence of bone mass loss, due to biological factors or to some diseases such as osteoporosis. The study is based on a computational structural optimization model for bone remodeling in which trabecular bone is modeled as an orthotropic porous material with periodic microstructure and the driving stimulus for remodeling is the structure (bone) global stiffness. The objective of this study is to inquire if the bone loss is followed by a proportional reduction of effective material properties maintaining orthotropy levels in different directions or, on contrary, the orthotropy level changes, stiffening the microstructure in one direction and weakening it in the other directions. For this purpose several material unit cells, characterizing the porous material, are tested and the respective homogenized material properties are analyzed by suitable anisotropy measures. Results, obtained for a simplified model of a human vertebra, show that directions with higher load levels become proportionally stiffer than the others, in order to maintain bone integrity.