Optimization and Fabrication of Customized Scaffold Using Additive Manufacturing to Match the Property of Human Bone

Abstract

Additive manufacturing plays a major role in medical science. One of the applications is the development of bone scaffolds. During scaffold fabrication, obtaining the properties of the polyamide scaffolds to mimic the elastic properties of human subchondral bone is a challenging task. In order to overcome this challenge, the present numerical study validated by experimental routine allows optimizing, fabricating and automating the generation of open porous polyamide scaffolds. Human subchondral bone has an elastic modulus of 1.15 GPa and pore size of 800 μm which helps for cell ingrowth. The design parameters such as strut diameter (0.6-3 mm) and unit cell size (1.4-5 mm) were considered for this investigation. The optimized scaffold structure was fabricated using selective laser sintering method, one of the additive manufacturing (AM) processes and the structure was validated through uniaxial compression. Experimental test revealed a deviation in structural modulus of about 14, 10 and 17% for circular, square and hexagonal cross section, respectively. Optimized unit cell dimensions were found. The preliminary MTT (Methyl Thiazolyl diphenyl-Tetrazolium bromide) assay tests to evaluate the distributions of cells were performed, using in vitro perfusion culture experiments. It was found that the scaffold structure with square cross section has the maximum percentage of cell viability of 58.33%. A computer-aided design tool was developed using CATIA V5 Visual Basic program for modelling the bone scaffolds with better interconnectivity of unit blocks, porosity and compressive strength. This program facilitates automatic generation of optimized scaffold structure by providing necessary input parameters. The developed CAD tool was efficient enough to model the customized scaffold.