Optimizing Graded Porous Scaffolds for Bone Defects: Insights from In Vivo Mechanical Environments

Background: Bone tissue engineering has emerged as a promising technique for treating bone defects in large bones. Recent methods have enabled scaffold designs based on predefined microstructures or mechanical behavior patterns, including porosity-graded scaffolds adaptable to heterogeneous load states. However, there is no consensus on the optimal scaffold design strategy, which is sometimes chosen based on the intact bone or results from computational or in vivo experiments. Objective: This work proposes the design of graded-porosity triply periodic minimal surface (TPMS) scaffolds that mimic the mechanical environment within a bone transport callus at the peak of bone tissue production, according to in vivo load measurements. Methods: Finite element models based on computational tomography scans were used to define the strain field of the callus at the peak of bone tissue production. The developed scaffold models were evaluated through finite element simulation. Results: The callus simulations reported that the period in which maximum woven bone tissue production was achieved corresponds to the period of maximum axial strain. The graded-porosity scaffolds simulated demonstrated their ability to replicate this strain field along the callus. The microstructural parameters and strain environment of the proposed graded-porosity scaffolds were consistent with finding from studies assessing the influence of different microstructural parameters or strain conditions on bone ingrown within scaffolds. Conclusions: The proposed approach—designing graded-porosity scaffolds based on the callus strain field at the peak of bone tissue production—proved to be appropriate and may help improve future clinical applications.