Material and Geometric Innovations in Lumbar and Cervical Interbody Devices: A Systematic Scoping Review

Contemporary interbody spacer designs for spinal fusion surgeries have progressed due to significant mechanical and biological constraints. This scoping review aims to identify and assess current advancements in lumbar and cervical interbody spacer designs, with a focus on geometric configurations and material compositions that minimize subsidence and stress shielding. In accordance with PRISMA-ScR principles, a comprehensive examination of scientific literature and issued patents was performed. The results indicated that the latest advancements emphasize biomechanical optimization via topological design, porosity regulation, and biomimetic architectures. Among the assessed materials, 3D-printed porous titanium and PEEK-coated Ti were identified as promising alternatives, providing a balance of mechanical stability and osseointegration. Additionally, innovative geometries, including gyroid and helicoidal structures were reported to improve stress distribution and facilitate bone ingrowth, thereby reducing implant failure. The evidence suggests a clear trend toward the development of implants that replicate the mechanical and morphological characteristics of cortical bone.