Interstitial fluid transport in cortical bone porosities: Effects of blood pressure and mass exchange using porous media theory

This research focuses on the importance of understanding bone adaptation for gaining insights into diseases such as osteoporosis. The study investigates the role of fluid flow in cortical bone adaptation, with a specific focus on the network of osteocyte canaliculi and the chemical reactions involved in bone resorption. Prior studies have implemented methods such as poroelasticity theory and dual porosity, but these models did not account for mass exchange between the solid and fluid phases within the bone or the pressure exerted by arteries. The movement of interstitial fluid between the vascular porosity and lacuno-canalicular porosity in cortical bone, as well as the velocity of the fluid, are affected by both the pressure exerted by arteries and the exchange of mass between the solid and fluid components of the bone. To incorporate these effects in the model, the authors propose a dual porosity model based on the theory of porous media. The model considers the transfer of mass between vascular and lacunar-canalicular porosities, as well as between solid and fluid phases, while also accounting for blood pressure variations. To verify the proposed model, a numerical example is solved and compared with the results of previous studies. The model enables the measurement and analysis of the interstitial fluid velocity and the pressure in the respective porosities. The results reveal that accounting for blood pressure pulses and mass exchange between solid and fluid phases can alter the velocity and pressure fields of interstitial fluid within cortical bone. In addition, this study investigates transient examples and various scenarios of the bone remodeling. Overall, this research provides a more accurate understanding of the bone remodeling and the effects of blood pressure variation and mass exchange between solid and fluid phases of cortical bone.