Optimization of 3D-printed titanium interbody cage design. Part 2: An in vivo study of spinal fusion in sheep

• Published in: The spine journal 2024-12
• Main Authors: Lombardo, Jeremy A., Wills, Dan, Wang, Tian, Pelletier, Matthew, Farber, S. Harrison, Kelly, Brian P., Uribe, Juan S., Turner, Jay D., Vizesi, Frank, Walsh, William R.
• Format: Article
• Language: English
• Subjects: 3D-printed titanium; autograft; biomechanics; bone graft; bone histology; interbody fusion; large animal model; lateral interbody fusion; porous titanium; sheep
• ISSN: 1529-9430
• DOI: 10.1016/j.spinee.2024.12.014

3D-printed titanium cage designs can incorporate complex, porous features for bone ingrowth and a greater surface area for minimizing subsidence. In a companion study (Part 1), we determined that increased surface area leads to decreased subsidence; however, it remains unclear how increasing the cage surface area, resulting in a smaller graft aperture, influences fusion. We evaluated the effects of surface area of 3D-printed titanium cages and the use of autologous bone grafts on spinal fusion in sheep. In vivo large animal study in 12 sheep. Interbody fusion was performed in 12 adult sheep at 24 levels (L2-3 and L4-5) using 3D-printed titanium cages with bilateral pedicle screw fixation. The cage designs varied in aperture: standard (low endplate surface area), small (medium endplate surface area), or none (high endplate surface area). These cages were packed with autologous iliac crest bone grafts (ICBG). A fourth group was implanted without bone grafts, using the no-aperture cage. Fusion was evaluated at 16 weeks via manual palpation, microcomputed tomography (microCT), histology, and histomorphometry. Standard, small, and no-aperture cages packed with ICBG resulted in high fusion rates (80%, 100%, and 83%, respectively) at 16 weeks by manual palpation, and these results were not significantly different. Implantation without ICBG was associated with a significantly lower fusion rate (33%, p