Computational modelling of trabecular bone structure using fluid-structure interaction approach

Abstract

While doing daily physiological activities, trabecular bone will experience certain amount of deformation, which causes movement of the bone marrow. The bone marrow movement could affect the bone remodelling process. The properties of the bone will also be affected as the bone marrow acts as a hydraulic stiffening to the trabecular structure. Previous studies on trabecular bone remodelling did not consider the effects of bone marrow movement. Thus, there is a need to perform combined analyses of the bone marrow movement with trabecular structure to assess its effects on the remodelling process under a realistic condition. The aim of this study is to determine the effect of bone marrow movement onto the trabecular bone structure under mechanical loading using fluid-structure interaction (FSI) approach. Two different models of the trabecular bone, namely idealised and actual were constructed. The idealised models were used to correlate the bone marrow behaviour to the trabecular bone morphology. The actual trabecular bone models were constructed to mimic the presence of the bone marrow within the trabecular bone structure during physiological loading. The effects of different orientation of the trabecular structures were also examined. Three numerical approaches which are finite element method, computational fluid dynamics and FSI were employed to evaluate the importance of bone marrow movement effect towards the trabecular bone mechanical properties. The findings show that the bone cells are able to stimulate the bone remodelling process under the normal walking gait loading. The bone marrow behaviour such as shear stress, pressure and permeability, together with bone porosity and surface area, have a significant relationship with a p-value < 0.05. The longitudinal permeability and stiffness were respectively 83% and 56% higher, compared to the transverse orientation. The shear stress during a normal walking phase was in a range of 0.01- 0.27 Pa. These are sufficient to regulate cell response. It was also found that the stiffness of the trabecular bone structure is 22% higher compared to the models without the bone marrow. This finding suggests that the presence of the bone marrow could help to reduce the deformation and stresses on the trabecular bone structure.