Microstructural changes associated with osteoporosis negatively affect loading-induced fluid flow around osteocytes in cortical bone

• Published in: Journal of biomechanics Vol. 66; pp. 127 - 136
• Main Authors: Gatti, Vittorio, Azoulay, Evan M., Fritton, Susannah P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 03-01-2018; Elsevier Limited
• Subjects: Age; Animal models; Animals; Biocompatibility; Bone fluid flow; Bone loss; Bones; Computational fluid dynamics; Computed tomography; Computer architecture; Cortical bone; Cortical Bone - physiology; Extracellular Fluid - physiology; Female; Finite Element Analysis; Finite element method; Fluid flow; Fluids; Lacunar-canalicular system; Mathematical analysis; Mathematical models; Mechanical loading; Mechanotransduction; Mechanotransduction, Cellular; Microstructure; Models, Biological; Morphology; Osteocyte; Osteocytes; Osteocytes - physiology; Osteoporosis; Osteoporosis - physiopathology; Ovariectomy; Parametric analysis; Permeability; Physiology; Poroelasticity; Porosity; Post-menopause; Rats; Rats, Sprague-Dawley; Rodents; Stress analysis; Velocity; Osteoporosis; Lacunar-canalicular system; Osteocyte; Poroelasticity; Bone fluid flow
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2017.11.011

Loading-induced interstitial fluid flow in the microporosities of bone is critical for osteocyte mechanotransduction and for the maintenance of tissue health, enhancing convective transport in the lacunar-canalicular system. In recent studies, our group has reported alterations of bone’s vascular porosity and lacunar-canalicular system microarchitecture in a rat model of postmenopausal osteoporosis. In this work, poroelastic finite element analysis was used to investigate whether these microstructural changes can affect interstitial fluid flow around osteocytes. Animal-specific finite element models were developed combining micro-CT reconstructions of bone microstructure and measures of the poroelastic material properties. These models were used to quantify and compare loading-induced fluid flow in the lacunar-canalicular system of ovariectomized and sham-operated rats. A parametric analysis was also used to quantify the influence of the lacunar-canalicular permeability and vascular porosity on the fluid velocity magnitude. Results show that mechanically-induced interstitial fluid velocity can be significantly reduced in the lacunar-canalicular system of ovariectomized rats. Interestingly, the vascular porosity is shown to have a major influence on interstitial fluid flow, while the lacunar-canalicular permeability influence is limited when larger than 10-20m2. Altogether our results suggest that microstructural changes associated with the osteoporotic condition can negatively affect interstitial fluid flow around osteocytes in the lacunar-canalicular system of cortical bone. This fluid flow reduction could impair mechanosensation of the osteocytic network, possibly playing a role in the initiation and progression of age-related bone loss and postmenopausal osteoporosis.