It has been found for more than one century that when experiencing mechanical loading, the structure of bone will adapt to the changing mechanical environment, which is called bone remodeling. Bone remodeling is charaterized as two processes of bone formation and bone resorption. A large number of studies have confirmed that the shear stress is resulted from interstitial fluid flow within bone cavities under mechanical loading and it is the key factor of stimulating the biological responses of bone cells. This review summarizes the major research progress during the past years, including the biological response of bone cells under fluid flow, the pressure within bone cavities, the theoretical modeling, numerical simulation and experiments about fluid flow within bone, and finally analyzes and predicts the possible tendency in this field in the future.
There are two main types of fluid in bone tissue: blood and interstitial fluid. The metabolism of cells mainly relies on the microenvironment of the interstitial fluid. Researches of osteonal fluid seepage behavior based on the microstructure of bone tissue have become a hot point. The aim of the present research work is to assess the effect of blood pressure oscillation on the osteonal interstitial fluid seepage behavior. We established finite element osteon models for a hollow and that considering blood pressure oscillation, respectively, with COMSOL Multiphysics software in order to compare their fluid flow behavior under the axial loading. The results predicted that the interstitial fluid pressure field was enlarged considering the blood pressure oscillation, while the velocity filed changed little. Specifically, the increase of blood pressure oscillatory amplitude could result in the increase of osteonal interstitial fluid pressure, while the blood pressure oscillatory frequency had limited effects on the osteonal pore fluid pressure. Moreover, the blood pressure oscillatory amplitude and frequency had no effect on the osteonal interstitial fluid velocity. The finite element model can be used for the study of the poroelastic behaviors of the osteon under non-axisymmetric loads and microcracks, and can also be a new way to study the mechanism of bone mechanotransduction and electromechanotransduction.