Improved osseointegration and segmental stability of 3D-printed porous tantalum cages with micro-scale structures for spinal fusion

Spinal fusion surgery is an effective therapy for patients with disc herniation and degenerative disc disease. In this procedure, the intervertebral cage plays a key role in reconstructing stability and achieving fusion, yet its clinical efficacy is limited by inadequate osseointegration. In this study, we developed a tantalum (Ta) cage featuring micro-scale roughness and a porous microstructure, using advanced 3D printing techniques. The aim of the study was to investigate its osteogenic potential in vitro and intervertebral fusion capability in vivo. Compared with conventional PEEK cages, in vitro biological experiments demonstrated that the 3D-printed porous Ta (3D-pTa) cages significantly enhanced osteoblast adhesion, proliferation, and differentiation. In vivo spinal fusion studies in a goat model demonstrated significant increases in bone-implant contact and bone volume to total volume ratios (P < 0.05) with the 3D-pTa cages, indicating marked bone ingrowth and effective spinal fusion. Additionally, mechanical tests revealed that the 3D-pTa cages provided consistent stability and stiffness, significantly reducing range of motion (ROM) at various time points (P < 0.05). Our findings indicate that the 3D-pTa cage effectively facilitates bone fusion and possesses reliable biosafety, highlighting its potential for future clinical application in spinal surgery.