The effect of pore size on the stiffness of composite scaffold

Abstract

Low mechanical stiffness is often an issue in the design of implant scaffolds that are required to have moderate porosity. The purpose of our study is to determine the optimal pore size for a given porosity, so that the scaffold has maximum stiffness. The composite scaffold we studied consists of hydroxyapatite (HA) and polylactic acid (PLA). The microstructure-free finite element modeling (MF-FEM), a finite element approach recently developed for the modeling of composite materials, was adopted for this study. We first compared MF-FEM predictions with conventional formulas of stiffness-porosity relation for the purpose of validation. Then, MF-FEM was used to investigate the effect of pore size on scaffold stiffness in single-phase scaffold, because none of the conventional formulas can predict the effective stiffness of two-phase porous composites. The results show that MF-FEM has excellent agreement with well-established analytical formulas; pore size roughly has a linear effect on both Young's modulus and shear modulus of composite scaffold, i.e. larger pore size leads to higher stiffness.