3D-printed porous titanium scaffolds for osseointegration: Role of pore design and surface micro- and nano-structures

3D printing offers significant advantages for orthopedic implants by enabling customized architectures and controlling structural parameters. Macro-porous structures are essential for tissue integration, as they support cell ingrowth and nutrient diffusion. Pore size, lattice geometry, and micro- and nanoscale structures have been frequently studied individually, but combined effects on osseointegration remain poorly understood. This study investigates the influence of pore size, pore geometry and surface micro- and nano-topography on the osteogenesis of human mesenchymal stem cells. Titanium alloy discs with nine different pore designs (varying pore size, and lattice design) were 3D-printed using Laser Powder Bed Fusion. An acid-alkaline heat treatment was used to create micro- and nano-surface structures. The results show that pore geometries primarily affect cell density and the depth of cell ingrowth within the pores, while micro- and nanostructures enhance osteogenic differentiation. This enhancement is associated with activation of mechanotransduction ion channels, leading to increased production of bone extracellular matrix, including collagen type I and calcium. These findings emphasize the importance of multi-scale design strategy combining macrostructural geometry with micro- /nano-scale surface features. Particularly, Diamond lattice implant with larger pore sizes and micro-/nano-structured surface, improves collagen matrix production, calcium deposition, suggesting a promising approach for bone-implant integration.