Poster AA4 - Optimization of 3D-Printed Titanium Scaffolds: Enhanced Biomechanical and Biological Performance through Pore Structure and Surface Topography

Introduction: Orthopedic implants are essential for treating bone defects and fractures, providing crucial mechanical support to restore skeletal function. Recent advancements in metal 3D printing, particularly Powder Bed Fusion (PBF) technology, have enabled the precise fabrication of porous titanium scaffolds, which enhance osseointegration and mitigate stress shielding. This study investigates the optimization of key laser parameters in Selective Laser Melting (SLM) to minimize shape error in pore sizes and improve the mechanical and biological performance of titanium scaffolds. Specifically, scaffolds with varying pore sizes (400 μm, 600 μm, 800 μm, and 1000 μm) and gradient structures were evaluated for their impact on osteoblast and endothelial cell behavior, along with the influence of surface topography on cellular responses.

Materials and

Methods: Titanium scaffolds were designed using CAD software (Rhinoceros 3D) with the Voronoi-Tessellation method, creating various pore sizes and gradients. Ti-6Al-4V grade 23 powder was used, and the scaffolds were fabricated using an SLM machine (MetalSys 150E) with optimized laser parameters (80-160 W and 550-950 mm/s). Micro-CT imaging was employed for structural characterization. Mechanical properties were assessed using a universal testing machine. Surface topography was analyzed to determine its effects on cell behavior. Osteoblast (Saos-2) and endothelial cell (HUVEC) proliferation were evaluated through cell culture assays and immunofluorescence imaging.

Results, Conclusions, and Discussions:

Results: Optimization of laser parameters, specifically at 80 W and 950 mm/s, minimized shape error and maintained appropriate pore sizes for osseointegration. Micro-CT analysis revealed slight deviations in pore sizes from the intended designs, yet the overall structure adhered to the targeted specifications. Mechanical testing indicated that scaffolds with pore sizes of 600-1000 μm closely resembled the properties of cortical bone, with elastic modulus values measured at 15.88 ± 2.25 GPa and yield strength at 282.48 ± 17.12 MPa for 600 μm pores. Surface topography analysis showed that laser parameters significantly influenced the roughness of the scaffold surfaces, which in turn affected cell attachment and proliferation. Osteoblast proliferation was highest on scaffolds with 1000 μm pores, while HUVECs thrived on 400 μm pores. Gradient scaffolds demonstrated enhanced proliferation of both cell types, suggesting a balanced approach for promoting osseogenesis and neovascularization. Surface roughness contributed to improved cell adherence and proliferation, with triangular and rectangular pores exhibiting the highest cell proliferation due to their valley-like surface topography.

Conclusions: 3D-printed titanium scaffolds with optimized pore structures and surface topography significantly enhance both mechanical and biological performance. Gradient pore sizes in scaffolds, combined with controlled surface roughness, provide a comprehensive solution for optimizing osseointegration and vascularization. These findings suggest that such scaffold designs could revolutionize the field of bone tissue engineering, offering improved clinical outcomes for patients requiring orthopedic implants.
Discussions: This research underscores the potential of using functionally graded pore sizes and tailored surface topography in titanium scaffolds to optimize biomechanical and biological properties. The study highlights the importance of gradient pore structures and surface roughness in scaffolds, which mimic natural bone properties and promote tissue integration. Future studies, including in vivo experiments, are necessary to confirm these results and explore the long-term effects of these advanced scaffold designs on bone healing and integration.

Acknowledgements (Optional): This work was supported by the Korea Medical Device Development Fund grant funded by the Korea government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, and the Ministry of Food and Drug Safety) (Project Number: RS-2020-KD000038).