Numerical Study on the Morphology and Mechanical Role of Healthy and Osteoporotic Vertebral Trabecular Bone

Abstract

This study presents a numerical methodology to clarify the morphology of complex trabecular network architecture in human lumbar vertebra by means of the new post-processing technique for calculated microscopic stress by the homogenization method. Micro-CT image-based modeling technique is used and careful but intuitive and easy-to-use method for microstructure model, in other words region of interest (ROI), is also presented. The macroscopic homogenized properties that include not only the Young's moduli but also shear moduli could explain the difference of morphology between healthy and osteoporotic bones. This paper focuses on the change of degree of anisotropy. Then, the microscopic stress under three basis load cases was analyzed. In this analysis, the homogenization method has a merit in the computational cost. The trabeculae are classified into eight groups from the viewpoint of load bearing function against three loading conditions in the proposed post-processing of numerical results. It contributes to the understanding of the mechanical role of trabecular bone in vertebra. The primary trabecular bone that has been supposed to support the self-weight and secondary bone that connects the primary bone are successfully visualized. The discussion on the mechanical role of plate-like trabecular bone in the load path network system is also highlighted.

Multiscale stress analysis of trabecular bone around acetabular cup implant by finite element mesh superposition method

“…The orthotropy of the trabecular bone is natural and can be seen also in vertebra and so on, to support the primary external load. In vertebral trabecular bone, the maximum Young's modulus is in the vertical direction to support the self-weight [Yoshiwara, et al, 2011]. Also in this analysis, the primary orthogonal direction of the trabecular bone which provides the maximum Young's modulus, direction in Fig.…”

“…The bone volume fraction in the unit cell model is 10.6 %. Isotropic material model is used for the bone tissue, whose Young's modulus and poisson's ratio are 15 GPa and 0.3 (Yoshiwara, et al, 2011). Those of wrapping elements are 0.015 MPa and 0.3, respectively.…”

“…2(b). The macroscopic material model was calculated by homogenization method, whose reliability has been validated for engineering materials (Takano, et al, 2003) as well as human vertebral trabecular bone (Yoshiwara, et al, 2011).…”

Uncertainty Modeling in the Prediction of Effective Mechanical Properties Using Stochastic Homogenization Method with Application to Porous Trabecular Bone

“…15) It has been confirmed the ROI size is not so much influential on the final result. 4) For the above reasons, the threshold value and ROI size are excluded from the uncertainty factors.…”

“…Next, the fluctuation of the Young's modulus in the other two orthogonal axes was set as half of that in principal axis 4) as written in eq. (17).…”