Approximation of the Role of Mineralized Collagen Fibril Orientation in the Mechanical Properties of Bone: A Computational Study on Dehydrated Osteonal Lamellar Bone

Abstract

Bone is a natural composite of the hierarchical arrangement of mineralized collagen fibrils in various orientations. This study aims to understand how the orientation of the bone mineral, guiding the removal of water contained in the humidity-responsive layers during dehydration, affects its mechanical properties. A sublamellar pattern with mineralized collagen fibrils oriented between 0° to 150° at 5° angles was the model studied. Using basic transformational computational methods, dimensional change was calculated in the transverse and oblique planes of osteonal lamellar bone while considering bone components sensitive to dehydration in radial, tangential, and axial orientations. The anisotropy ratios of the change in the dimension of the variable mineralized collagen fibril orientations calculated using the computed model displayed values ranging between 0.847 to 2.092 for the transverse plane and 0.9856 to 1.0207 for the oblique plane. A comparison of the anisotropy results of the suggested model indicated that they approach the experimental results of both transversely and obliquely cut samples. As collagen fibril and mineral orientation take place both temporally and spatially in relationship with the static and dynamic loads placed on the different volumes of bone, the results may imply that the mechanical demands involved in bone resorption and deposition contribute to the formation of this multi-faceted and hierarchically structured natural composite.