Evaluation of biological performance of 3D printed trabecular porous tantalum spine fusion cage in large animal models.

Background: The materials for artificial bone scaffolds have long been a focal point in biomaterials research. Tantalum, with its excellent bioactivity and tissue compatibility, has gradually become a promising alternative material. 3D printing technology shows unique advantages in designing complex structures, reducing costs, and providing personalized customization in the manufacture of porous tantalum fusion cages. Here we report the pre-clinical large animal (sheep) study on the newly developed 3D printed biomimetic trabecular porous tantalum fusion cage for assessing the long-term intervertebral fusion efficacy and safety. Methods: Porous tantalum fusion cages were fabricated using laser powder bed fusion (LPBF) and chemical vapor deposition (CVD) methods. The fusion cages were characterized using scanning electron microscopy (SEM) and mechanical compression tests. Small-Tailed Han sheep served as the animal model, and the two types of fusion cages were implanted in the C3/4 cervical segments and followed for up to 12 months. Imaging techniques, including X-ray, CT scans, and Micro CT, were used to observe the bone integration of the fusion cages. Hard tissue sections were used to assess osteogenic effects and bone integration. The range of motion (ROM) of the motion segments was evaluated using a biomechanical testing machine. Serum biochemical indicators and pathological analysis of major organs were conducted to assess biocompatibility. Results: X-ray imaging showed that both the 3D-printed and chemical vapor deposition porous tantalum fusion cages maintained comparable average intervertebral disc heights. Due to the presence of metal artifacts, CT and Micro CT imaging could not effectively analyze bone integration. Histomorphology data indicated that both the 3D-printed and chemical vapor deposition porous tantalum fusion cages exhibited similar levels of bone contact and integration at 3, 6, and 12 months, with bone bridging observed at 12 months. Both groups of fusion cages demonstrated consistent mechanical stability across all time points. Serum biochemistry showed no abnormalities, and no significant pathological changes were observed in the heart, liver, spleen, lungs, and kidneys. Conclusion: This study confirms that 3D-printed and chemical vapor deposition porous tantalum fusion cages exhibit comparable, excellent osteogenic effects and long-term biocompatibility. Additionally, 3D-printed porous tantalum fusion cages offer unique advantages in achieving complex structural designs, low-cost manufacturing, and personalized customization, providing robust scientific support for future clinical applications. The translational potential of this article: The translational potential of this paper is to use 3D printed biomimetic trabecular porous tantalum spine fusion cage with bone trabecular structure and validating its feasibility in large animal models (sheep). This study provides a basis for further research into the clinical application of the 3D printed biomimetic trabecular porous tantalum spine fusion cage.