Finite element-based design and analysis of lattice-structured lumbar interbody fusion cages for additive manufacturing applications

This study presents the development and biomechanical assessment of a finite element model for lumbar interbody fusion cages incorporating three distinct lattice architectures—body-centered cubes (BCCs), face-centered cubes, and face diagonal cubes (FDCs)—fabricated using additive manufacturing. Two commonly used biomaterials, polyether ether ketone (PEEK) and Ti-6Al-4 V titanium alloy, were considered for cage construction. The validated L4–L5 lumbar spine segment was subjected to physiological loading conditions comprising a pure moment of 7.5 Nm and an axial follower load of 280 N across six primary postures: flexion, extension, left and right lateral bending, and left and right axial rotation. The analysis focused on total deformation and von Mises stress (VMS) distribution in both the cages and vertebral endplates. The results revealed that the FDC lattice PEEK cage experienced the highest deformation of 0.623 mm during lateral bending, while the BCC lattice made of Ti-6Al-4 V exhibited the lowest VMS of 119 MPa, demonstrating superior load-bearing behavior. Endplate stress analysis indicated that the BCC lattice with PEEK effectively reduced localized stresses at the L4 and L5 interfaces, confirming favorable biomechanical compatibility. These outcomes emphasize the combined influence of lattice geometry, material selection, and spinal posture on implant performance, offering valuable guidance for optimizing interbody fusion device designs.