MICROSTRUCTURE EFFECT ON BONE FORMATION OF A FUNCTIONALLY GRADED SCAFFOLD USING A MECHANOSTAT-BASED MODEL

Jun 29, 2022, 2:20 PM
10m
Room: S2

Room: S2

Speaker

Alipour Ghassabi, Ata (Faculty of Engineering and Natural Sciences, Mechatronics Engineering, Sabanci University )

Description

"From a mechanical point of view, bone demonstrates exceptional mechanical properties owing to its complex hierarchical composite structure. The human skeleton acts as a support for the whole body as it withstands stresses produced by daily routines and gravitational force. As a result of these stresses, the bone regulates its geometry and density through activating formation and resorption mechanisms (Pivonka, 2018). Different mechano-regulatory theories were developed to address the dependency of the bone remodeling mechanism on mechanical stimulation at multiple scales. At tissue scale, where the bone is considered as a homogeneous material, the strain energy density (SED), effective stress, octahedral shear strain and interstitial fluid flow have been examined as the driving force for bone formation and resorption mechanisms. Advances in computational power and numerical techniques have extended the ability to apply these mathematical schemes to large-scale problems involving the design and optimization of scaffolds for large bone defects. Numerical schemes, such as finite element method (FEM), boundary element method (BEM), and meshless methods have been used to simulate bone remodeling, among which, FEM is by far the most used method (García-Aznar et al., 2021). Design of scaffolds faces numerous challenges at different scales and physics. One of the ongoing challenges is to optimize the microstructure of the scaffold to maximize the efficacy of the scaffold as a supporting structure for bone formation. For this reason, functionally graded scaffolds (FGSs) are designed which closely resemble the mechanical, biological, and morphological properties of the bone structure (Zhang et al., 2018). In this study, an FEM-based approach (Shi et al., 2018) was adopted to investigate the effect of porosity variation on bone formation inside an FGS incorporating both degradation and regeneration. The SED-based feedback mechanism was employed to consider the effect of mechanical stimuli on bone formation of a FGS. Bulk, surface, and stochastic degradations were considered in modeling of the scaffold degradation for the first time for a FGS. The aim of this study is to evaluate the effect of microstructure on the bone formation inside an FG bone scaffold and establish the basis for potential future studies on optimization studies of FGSs for maximum performance. The reported results can be used as benchmark solutions for future numerical analysis of the bone formation inside FGSs and serve as a means to validate future in-vivo or in-vitro experimental results.

References
García-Aznar, J. M. et al., Bone. 116032 (2021).
Pivonka, P. (Ed.). Springer International Publishing. (2018)
Shi, Q. et al., Biomechanics and modeling in mechanobiology. 17(3), 763-775 (2018)
Zhang, X. Y. et al., Materials & Design. 157, 523-538 (2018)"

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