Functional disuse initiates medullary endosteal micro-architectural impairment in cortical bone characterized by nanoindentation

In this study, we evaluated the effect of functional disuse-induced bone remodeling on its mechanical properties, individually at periosteum and medullary endosteum regions of the cortical bone. Left middle tibiae were obtained from 5-month-old female Sprague –Dawley rats for the baseline control as well as hindlimb suspended (disuse) groups. Micro-nano-mechanical elastic moduli (at lateral region) was evaluated along axial (Z), circumferential (C) and radial (R) orientations using nanoindentation. Results indicated an anisotropic microstructure with a xial orientation having the highest and radial orientation with the lowest moduli at periosteum and medullary endosteum for both baseline control as well as disuse groups. Between the groups: at periosteum, an insignificant difference was evaluated for each of the orientations (p >  0.05) and at endosteum, a significant decrease of elastic moduli in the radial (p <  0.0001), circumferential (p <  0.001) and statistically insignificant difference in axial (p >  0.05) orientation. For the moduli ratios between groups: at periosteum, only significant difference in the Z/R (p <  0.05) anisotropy ratio, whereas at endosteum, a statistically significant difference in Z/C (p <  0.001), and Z/R (p <  0.001), as well as C/R (p <  0.05) anisotropy ratios, was evaluated. The results suggested initial bone remodeling impaired bone micro-architecture predominantly at the medullary e...
Source: Journal of Bone and Mineral Metabolism - Category: Orthopaedics Source Type: research