Relationship between the morphological, mechanical and permeability properties of porous bone scaffolds and the underlying microstructure

Abstract

Bone scaffolds are widely used as one of the main bone substitute materials. However, many bone scaffold microstructure topologies exist and it is still unclear which topology to use when designing scaffold for a specific application. The aim of the present study was to reveal the mechanism of the microstructure-driven performance of bone scaffold and thus to provide guideline on scaffold design. Finite element (FE) models of five TPMS (Diamond, Gyroid, Schwarz P, Fischer-Koch S and F-RD) and three traditional (Cube, FD-Cube and Octa) scaffolds were generated. The effective compressive and shear moduli of scaffolds were calculated from the mechanical analysis using the FE unit cell models with the periodic boundary condition. The scaffold permeability was calculated from the computational fluid dynamics (CFD) analysis using the 4×4×4 FE models. It is revealed that the surface-to-volume ratio of the Fischer-Koch S-based scaffold is the highest among the scaffolds investigated. The mechanical analysis revealed that the bending deformation dominated structures (e.g., the Diamond, the Gyroid, the Schwarz P) have higher effective shear moduli. The stretching deformation dominated structures (e.g., the Schwarz P, the Cube) have higher effective compressive moduli. For all the scaffolds, when the same amount of change in scaffold porosity is made, the corresponding change in the scaffold relative shear modulus is larger than that in the relative compressive modulus. The CFD analysis revealed that the structures with the simple and straight pores (e.g., Cube) have higher permeability than the structures with the complex pores (e.g., Fischer-Koch S). The main contribution of the present study is that the relationship between scaffold properties and the underlying microstructure is systematically investigated and thus some guidelines on the design of bone scaffolds are provided, for example, in the scenario where a high surface-to-volume ratio is required, it is suggested to use the Fischer-Koch S based scaffold.

Ce/Sm/Sr-Incorporating Ceramic Scaffolds Obtained via Sol-Gel Route

“…When designing new bone substituting materials, many factors must be considered, from pore size and shape, porosity degree and interconnectivity to surface chemistry and mechanical stability [ 51 ]. Thus, a delicate balance occurs between the necessity of allowing cells migration and proliferation, as well as vascularization, and the obligation to ensure the structural integrity through adequate mechanical properties [ 52 ].…”

A Critical Review on the Design, Manufacturing and Assessment of the Bone Scaffold for Large Bone Defects

“…For example, Woodard et al, (2007) implanted the porous scaffold into the latissimus dorsi muscle of Yorkshire pigs and found that the implanted scaffolds exhibited a stress-strain response similar to that of cancellous bone with strengths between those of cancellous and cortical bones. Li et al, (2016) implanted the porous FIGURE 6 | The analysis procedure for obtaining the properties of porous scaffolds using the finite element method (adapted from Lu et al, 2020a;Lu et al, 2020b). scaffold into the goat metatarsus and analyzed the stability of the implantation.…”

“… Adachi et al (2006) simulated the formation of new bones and scaffold degradations using the FE approach. It should be noted that among various mechanical properties, the effective elastic modulus is the most reliable one predicted from the FE analysis ( Lu et al, 2020b ). The accurate prediction of the nonlinear mechanical properties, such as the ultimate strength, the fatigue life, relies on the accurate definitions of the material models.…”

“… The analysis procedure for obtaining the properties of porous scaffolds using the finite element method (adapted from Lu et al, 2020a ; Lu et al, 2020b ). …”

“…Therefore, it is undoubtable that there are some discrepancies between the in silico analysis and the results from the experimental testing ( Lu et al, 2020a ). Nevertheless, the in silico analysis can still provide valuable results on the behaviors of different bone scaffolds ( Lu et al, 2020b ).…”