Structural Optimization of 3D-Printed Porous Titanium Implants Promotes Bone Regeneration for Enhanced Biological Fixation

Structural defects and biological inertness significantly impair the integration of titanium alloy implants and bone tissues. In spinal internal fixation, the issue of pedicle screw loosening or fracture caused by poor integration urgently needs solving. In this study, we utilized 3D printing technology to custom fabricate a structurally optimized porous pedicle screw with the aim of enhancing bone regeneration and integration at the defect site, thereby enhancing the biological fixation of the implant in vivo. Results showed that the structurally optimized porous unit has superior mechanical properties and actively promotes cell adhesion and growth at the surface interface. The porous screw based on this optimized structure has immediate bonding strength and bending resistance comparable to clinical products and provides an optimal spatial structure for newly regenerated bone ingrowth and integration. Alkali-thermal activation constructed a bioactive sodium titanate coating on the screw surface, which promoted the proliferation, adhesion, and osteogenic differentiation of BMSCs. This further enhances the biological performance of the implant surface interface, highlighting the advantages of structurally optimization. In the beagle vertebrae, the structurally optimized bioactive screw promoted the regeneration of surrounding bone and the inward growth of newly regenerated bone, strengthening the osseointegration strength at the implant interface and inside, thus synergistically enhancing biological fixation. This study pioneers the introduction of porous structure into a pedicle screw through structural optimization, which provides an innovative strategy for the development of spinal internal fixation and improves the potential value for advancing the utilization of 3D-printed orthopedic implants.