Abstract
BackgroundBone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions. The stress and strain distribution and fluid flow in bone play an important role in the realization of mechanotransduction and bone remodeling.MethodsTo investigate the mechanotransduction and fluid behaviors in loaded bone, a multiscale method was developed. Based on poroelastic theory, we established the theoretical and FE model of a segment bone to provide basis for researching more complex bone model. The COMSOL Multiphysics software was used to establish different scales of bone models, and the properties of mechanical and fluid behaviors in each scale were investigated.ResultsFE results correlated very well with analytical in macroscopic scale, and the results for the mesoscopic models were about less than 2% different compared to that in the macro–mesoscale models, verifying the correctness of the modeling. In macro–mesoscale, results demonstrated that variations in fluid pressure (FP), fluid velocity (FV), von Mises stress (VMS), and maximum principal strain (MPS) in the position of endosteum, periosteum, osteon, and interstitial bone and these variations can be considerable (up to 10, 8, 4 and 3.5 times difference in maximum FP, FV, VMS, and MPS between the highest and the lowest regions, respectively). With the changing of Young’s modulus (E) in each osteon lamella, the strain and stress concentration occurred in different positions and given rise to microscale spatial variations in the fluid pressure field. The heterogeneous distribution of lacunar–canalicular permeability (klcp) in each osteon lamella had various influence on the FP and FV, but had little effect on VMS and MPS.ConclusionBased on the idealized model presented in this article, the presence of endosteum and periosteum has an important influence on the fluid flow in bone. With the hypothetical parameter values in osteon lamellae, the bone material parameters have effect on the propagation of stress and fluid flow in bone. The model can also incorporate alternative material parameters obtained from different individuals. The suggested method is expected to provide dependable biological information for better understanding the bone mechanotransduction and signal transduction.
Highlights
Bone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions
According to Wolffs law, bone strength is determined by its structure, and bone structure is regulated by external mechanical stimuli and intelligently adapt to mechanical environment so as to bear the load in the optimum structural form and to obtain the maximum structural strength with the least structural material [4].Within the bone tissue, mechanical stress and bone structure keep a balance relationship that defined the activity of osteoblasts and osteoclasts, and there is a threshold for mechanical stress [5]
A region M was taken along the radius of the bone tissue (Fig. 1d), and some points were get at different positions of the endosteum, interstitial bone, osteon, and periosteum within the region M
Summary
Bone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions. The stress and strain distribution and fluid flow in bone play an important role in the realization of mechanotransduction and bone remodeling. Bone has composite hierarchical structures to achieve diverse mechanical, biological, and chemical functions, such as support and protection, transport, storage cells, and mineral ion homeostasis [1]. The stress and strain distribution and fluid flow in bone play an important role in the effective realization of various functions of bone. Fluid flow in osteons can produce a series of effect, such as fluid shear stress, pore pressure gradient, solute transport, and streaming potential, and some of these effects can be sensed by osteocytes as signals to trigger bone formation and bone resorption to adapt the continuous change of the mechanical environment [8]. It is significant to research the stress and strain field and the behaviors of fluid flow in different scales of bone under physiological load
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