Assessing mechanical behavior of ostrich and equine trabecular and cortical bone based on depth sensing indentation measurements

Abstract

Guided bone regeneration surgeries are based on grafting a scaffold in the site to be repaired. The main focus of the scaffold is to provide mechanical support to newly formed blood vessels and cells that will colonize the grafted site, achiving bone regenertation. In this regards, the aim of this study was to characterize the anatomy, structular, surface morphologycal, chemical composition, and nanomechanical properties of ostrich and equine trabecular bone. Ostrich and equine specimens were obtained from a local abattoir and bone was obtained by blunt dissection, n = 5. Tissue bone anatomy and trabecular structure were measured using Computerized Axial Tomography (CAT). Atomic Force Microscopy (AFM) and Energy dispersion spectrometry of X-ray (EDS) were used to examine surface morphology and chemical composition of the trabecular ostrich and equine bone. Mechanical behavior was analysted by nanoindentation. Equine specimens were examined as control. CAT results suggest that in terms of anthropometry, ostrich tarsometatarsus bone is more suitable due to its length is 432.56 ± 3.12 mm vs. the highest human bone structures reported, which femur length is 533.66 ± 18.81 mm. Besides, the low radiodensity in the Hounsfield scale exhibits equine trabecular bone more brittle (Av = 1538.4 ± 0.9) than ostrich trabecular bone (Av = 462.1 ± 1.5). EDS showed a slight variation of the element Calcium (Ca²⁺) ranging from 20% to 25.5% wt in equine bone; the Ca²⁺ content variation is consistent with the ring-shaped morphology, while in ostrich bone the chemical composition is homogeneous. The elastic modulus, nanohardness (E = 5.3 ± 0.7 GPa, H = 220 ± 10 MPa) and average roughness (Ra = 207 nm) are similar to the human trabecular bone which could reduce the stress shielding, all of these findings suggest that ostrich bone can be promising for native tissue scaffolds for mechanically demanding applications. This research makes innovative contributions to science and provides a framework, which will allow us to address future biomedical tests, and rapidly identify promising organic and sustainable waste for tissue scaffold.

Keywords: Elastic modulus; Hardness; Nanoindentation; Ostrich- equine bone; Scaffold; Trabecular bone.