A Novel Manufacturing Route for Fabrication of Topologically-Ordered Porous Magnesium Scaffolds

The use of porous metal foams as biomaterial scaffolds has been widely adopted; however, many of these porous structures are manufactured with pore architectures that are inherently random. This makes structural optimization for a specific purpose challenging. Scaffolds containing ordered pore architectures can be fabricated to meet design criteria, such as porosity, stiffness, and volume fraction. Mg and its alloys offer potential as a new class of degradable metallic orthopedic biomaterials. In comparison with current metallic orthopedic implant materials, Mg offers advantages such as, closer-to-bone stiffness and biodegradability, thereby eliminating the need for a second surgery to remove hardware. Currently there are few methods described in literature to manufacture ordered porous Mg. The aim of this study was to determine the resolution of a novel indirect solid free-form fabrication (SFF) process for producing topologically ordered Mg (TOPM) structures. The multi-step method involved the printing of an SFF mould, NaCl infiltration, and liquid Mg casting techniques. Using a range of characterization methods, we demonstrated that the selected structures were manufactured with a high level of accuracy. Differences in dimensions from CAD models to Mg scaffolds ranged from 2.5% to a maximum of 8.33%. Similarly, there was a maximum of 6.1% reduction in porosity in Mg scaffolds compared with initial design. Meanwhile, with surface roughness of 10.17 +/- 1.75 mu m, there was an average of 70% increase in surface area. This study demonstrates a simple, reliable, and safe route to manufacture TOPM scaffolds for potential application in medical device design.