Tissue scaffolds provide structural support while facilitating tissue growth, but are challenging to design due to diverse property trade-offs. Here, a computational approach was developed for modeling scaffolds with lattice structures of eight different topologies and assessing properties relevant to bone tissue engineering applications. Evaluated properties include porosity, pore size, surface-volume ratio, elastic modulus, shear modulus, and permeability. Lattice topologies were generated by patterning beam-based unit cells, with design parameters for beam diameter and unit cell length. Finite element simulations were conducted for each topology and quantified how elastic modulus and shear modulus scale with porosity, and how permeability scales with porosity cubed over surface-volume ratio squared. Lattices were compared with controlled properties related to porosity and pore size. Relative comparisons suggest that lattice topology leads to specializations in achievable properties. For instance, Cube topologies tend to have high elastic and low shear moduli while Octet topologies have high shear moduli and surface-volume ratios but low permeability. The developed method was utilized to analyze property trade-offs as beam diameter was altered for a given topology, and used to prototype a 3D printed lattice embedded in an interbody cage for spinal fusion treatments. Findings provide a basis for modeling and understanding relative differences among beam-based lattices designed to facilitate bone tissue growth.

Advances in additive manufacturing are enabling the fabrication of lattices with complex geometries that are potentially advantageous as tissue scaffolds. Scaffold design for optimized mechanics and tissue growth is challenging, due to complicated trade-offs among scaffold structural properties including porosity, pore size, surface-volume ratio, elastic modulus, shear modulus, and permeability. Here, a design for additive manufacturing approach is developed for tuning unit cell libraries as tissue scaffolds through (1) simulation, (2) design automation, and (3) fabrication. Finite element simulations are used to determine elastic and shear moduli of lattices as a function of porosity. Fluids simulations suggest that lattice permeability scales with porosity cubed over surface-volume ratio squared. The design automation approach uses simulation results to configure lattices with specified porosity and pore size. A cubic and octet lattice are fabricated with pore sizes of 1,000μm and porosities of 60%; these lattice types represent unit cells with high unidirectional elastic modulus/permeability and high shear modulus/surface-volume ratio, respectively. Imaging suggests the 3D printing process recreates the form accurately, but distorts microscale features. Future iterations are required to determine how lattices perform in comparison to computational predictions. The developed approach provides the foundations of a design automation approach for optimized 3D printed tissue scaffolds informed by simulation and experiments.