  Additively manufactured hollow strut bioceramic scaffolds present a promising
strategy towards enhanced performance in patient-tailored bone tissue
engineering. The channels in such scaffolds offer pathways for nutrient and
cell transport and facilitate effective osseointegration and vascularization.
In this study, we report an approach for the slurry based additive
manufacturing of modified diopside bioceramics that enables the production of
hollow-strut scaffolds with diverse cross-sectional forms, distinguished by
different configurations of channel and strut geometries. The prepared
scaffolds exhibit levels of porosity and mechanical strength that are well
suited for osteoporotic bone repair. Mechanical characterization in orthogonal
orientations revealed that a square outer cross-section for hollow struts in
woodpile scaffolds gives rise to levels of compressive strength that are higher
than those of conventional solid cylindrical strut scaffolds despite a
significantly lower density. Finite element analysis confirms that this
improved strength arises from lower stress concentration in such geometries. It
was shown that hollow struts in bioceramic scaffolds dramatically increase cell
attachment and proliferation, potentially promoting new bone tissue formation
within the scaffold channel. This work provides an easily controlled method for
the extrusion-based 3D printing of hollow strut scaffolds. We show here how the
production of hollow struts with controllable geometry can serve to enhance
both the functional and mechanical performance of porous structures, with
particular relevance for bone tissue engineering scaffolds.
