Fig. 1.

The design and LPBF fabrication of NiTi alloy porous scaffolds. A: The flowchart depicting the fabrication process of the scaffolds. B and C: The process of porous structure topology optimization, including the finite element physical model and boundary conditions for both compression-type and torsion-type unit cells. This is followed by the models after topology optimization for these unit cells, as well as the LPBF-processed topologically optimized versions. D–F: Three types of cellular structures: the traditional octahedral type (D), the topologically optimized compression type (E), and the torsion type (F), accompanied by schematic diagrams of the corresponding porous scaffolds. G: LPBF-processed NiTi alloy porous scaffolds, featuring compression, octahedral, and torsion cell structures, were compared to a titanium alloy (Ti-6Al-4V) porous scaffold with an octahedral cell structure, which served as the control group. The dimensions of the porous scaffold utilized for in vitro biological experiments were 10 mm × 10 mm × 2 mm. For in vivo animal experiments, the cylindrical porous scaffold measured φ3 mm × 5 mm, while the cubic porous scaffold employed for physical performance tests was 10 mm × 10 mm × 10 mm in size. H–K: SEM observation of the porous scaffolds, a compression-type NiTi alloy porous scaffold (NiTi-C)(H), an octahedral-type NiTi alloy porous scaffold (NiTi-O)(I), a torsion-type NiTi alloy porous scaffold (NiTi-T)(J) and an octahedral-type titanium alloy porous scaffold (TC4-O)(K), respectively (scale bars = 1 mm).