TABLE 4.

State-of-art review on the optimization of the microstructure of bone scaffolds.

Type of microstructure	Objective function	Design variables	References
Scaffold with the dimension explicitly expressed	Maximize the scaffold stiffness or permeability	Stiffness	Xiao et al. (2018)
		Permeability	Dias et al. (2014)
	Maximize the newly formed bones	Computational mechanobiological model	Boccaccio et al. (2018)
		Geometrical parameters	Montazerian et al. (2019)
	Minimize the difference between the designed scaffold and the human bone	Biomechanical stability, Young’s modulus	Wieding et al. (2014)
Scaffold with the dimension implicitly expressed	Maximize the scaffold stiffness or permeability, or the minimum of the flexibility	Stiffness	Hollister and Lin (2007)
		Volume fraction	Xiao et al. (2012)
	Minimize the difference in the morphology, mechanical properties between the scaffold and the human bone	Geometrical parameters	Shi et al. (2018)
		Porosity, Young’s modulus and pore size	Vijayavenkataraman et al. (2018)
Non-periodic, irregular bionic microstructure	Minimize the difference in the morphology, mechanical properties between the scaffold and the human bone	Histomorphometry indices of trabecular bone	Gomez et al. (2016)
		Porosity	Wang et al. (2018b)