Gyroid (G) and primitive (P) porous structures have multiple application areas, ranging from thermal to mechanical, and fall in the complex triply periodic minimal surface (TPMS) category. Such intricate bioinspired constructs are gaining attention because they meet both biological and mechanical requirements for osseous reconstruction. The study aimed to develop G and P structures with varying porosity levels from 40% to 80% by modulating the strut thickness to proportionally resemble the stiffness of host tissue. The performance characteristics were evaluated using Ti6Al4V and important relationships between feature dimension, strut thickness, porosity, and stiffness were established. Numerical results showed that the studied porous structures could decrease stiffness from 107 GPa (stiffness of Ti6Al4V) to the range between 4.21 GPa to 29.63 GPa of varying porosities, which matches the human bone stiffness range. Furthermore, using this foundation, a subject-specific scaffold (made of P unit cells with an 80% porosity) was developed to reconstruct segmental bone defect (SBD) of the human femur, demonstrating a significant decrease in the stress shielding effect. Stress transfer on the bone surrounded by a P scaffold was compared with a solid implant which showed a net increase of stress transfer of 76% with the use of P scaffold. In the conclusion, future concerns and recommendations are suggested.
A mismatch between the implant and interacting bone Young's modulus causes stress shielding phenomena, which leads to instability of the implant and early failure. This paper focuses on the development of medical-grade titanium alloy (Ti6Al4V)-based metallic highly porous structure to mitigate the stress shielding effect. In this study, we propose an effective method to generate a highly porous implant based on triply periodic minimal surfaces (TPMS) architecture. Three-dimensional models of different TPMS architectures such as Diamond, Gyroid, I-graph-Wrapped Package graph (IWP), and Primitive were constructed with a 2 × 2 × 2 mm lattice size and unit cell size of 1 mm. Mechanical testing of the finite-element models was performed under static loading conditions to evaluate the effective elastic modulus ( Eeff) of each porous architecture. It was found that the primitive structure exhibits the lowest Eeff, whereas the Gyroid exhibits the highest Eeff, results indicate that porous architecture reduces Eeff by more than 95%, thereby reducing the stress shielding effect. Moreover, pore size and surface-area-to-volume ratio (SA/V ratio) were also investigated. Findings suggested that the primitive structure has the highest pore size, which will be suitable for enhanced bone ingrowth. A high SA/V ratio in IWP offers the possibility of enhanced cell adhesion, migration, and proliferation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.