Pressure and shear stress in trabecular bone marrow during whole bone loading

Abstract

Skeletal adaptation to mechanical loading is controlled by mechanobiological signaling. Osteocytes are highly responsive to applied strains, and are the key mechanosensory cells in bone. However, many cells residing in the marrow also respond to mechanical cues such as hydrostatic pressure and shear stress, and hence could play a role in skeletal adaptation. Trabecular bone encapsulates marrow, forming a poroelastic solid. According to the mechanical theory, deformation of the pores induces motion in the fluid-like marrow, resulting in pressure and velocity gradients. The latter results in shear stress acting between the components of the marrow. To characterize the mechanical environment of trabecular bone marrow in situ, pore pressure within the trabecular compartment of whole porcine femurs was measured with miniature pressure transducers during stress-relaxation and cyclic loading. Pressure gradients ranging from 0.013 to 0.46 kPa/mm were measured during loading. This range was consistent with calculated pressure gradients from continuum scale poroelastic models with the same permeability. Micro-scale computational fluid dynamics models created from computed tomography images were used to calculate the micromechanical stress in the marrow using the measured pressure differentials as boundary conditions. The volume averaged shear stress in the marrow ranged from 1.67 to 24.55 Pa during cyclic loading, which exceeds the mechanostimulatory threshold for mesenchymal lineage cells. Thus, the loading of bone through activities of daily living may be an essential component of bone marrow health and mechanobiology. Additional studies of cell-level interactions during loading in healthy and disease conditions will provide further incite into marrow mechanobiology.

The dysplastic trochlear sulcus due to the insufficient patellar stress in growing rats

“…In addition to the bone morphology, Yamada had found that the different distribution of cartilage on trochlear sulcus in patients with and without recurrent patellar dislocation [41]. Moreover, the previous studies had proved the abnormalities of trabecular under abnormal mechanical stress [42]. In this study, researchers found similar changes at different levels.…”

Effects of Loading Duration and Short Rest Insertion on Cancellous and Cortical Bone Adaptation in the Mouse Tibia

“…This would further suggest that the load duration-related response could be strain magnitude dependent, with bone tissues that are subjected to lower peak strains reaching a load duration saturation at fewer load cycles than tissues subjected to greater strain magnitudes. It is also possible that the cellular mechanisms of the cancellous and cortical bone tissues’ responses to mechanical loading could be different [38] due to differences in their biological microenvironment [39, 40]. Another possibility is that longer loading durations (e.g.…”

Physicochemical Niche Conditions and Mechanosensing by Osteocytes and Myocytes

“…In vivo, shear stress in trabecular bone during whole bone loading produces micro-scale interaction between bone marrow and trabecular bone. It affects the distribution of mechanical stress and strain in bone marrow and its cellular components, e.g., hematopoietic stem cells, osteoclasts, pre-osteoclasts, and macrophages [91]. Tatsumi et al [92•] developed a mouse model in which ~ 80% of the osteocytes are ablated upon injection with diphtheria toxin.…”