Section on innovative spine research and novel technologies: fusion cage design, materials, and coatings: Science versus hype.

Background: Interbody fusion has been performed for many decades with evolving strategies and approaches to improve safety, fusion rates, and clinical outcomes. There have been ongoing advancements in the understanding of spinal biomechanics driving improved implant designs. The advent of 3D printing has allowed new concepts of cage designs to become a reality. The purpose of this narrative review is to provide an overview of current and developing technologies in the area of fusion cage design as well as concerns of the impact of marketing versus science in this area. Methods: A literature search was conducted on PubMed and OVID to identify articles related to interbody fusion cage design. The focus of the review was on current and future interbody fusion cage design. Results: The area of fusion cage design has been rapidly growing. The greatest advancements have been in the area of additive manufacturing which has allowed for much more intricate implant design. Significant advancements have also been made in improving the surfaces of implants to promote osseointegration. Advancements in materials, manufacturing, and sensor technologies are paving the way for developing intelligent interbody fusion cages capable of monitoring fusion progression and potentially stimulating bone growth. Conclusion: There have been many exciting developments in the area of fusion cages, primarily related to materials, design, and surface topology, much of which have been driven by the advent of 3D printing. While many of these technologies may hold promise, there is relatively little data for the particular purported benefits of these implants. Much work is needed to understand the mechanobiological function of these devices, their clinical outcomes, indications, and cost-effectiveness.