Design, FEA and experimental validation of 3D-printed PLA/PCL intervertebral cages for lumbar spinal fusion

This study examines the mechanical performance of novel PLA/PCL intervertebral cage designs for lumbar spinal fusion, using FEA and experimental compression testing. Four 3D-printed cage designs with varying graft window sizes and structural volumes were tested for load-bearing capacity. Experimental compressive strengths ranged from 43.36 MPa for Cage 4-50.43 MPa for Cage 3, all meeting the mechanical requirements of spinal applications. Cage 2, with a dual-window design, exhibited optimal load distribution and the highest compressive strength (50.00 MPa), indicating enhanced stability. Conversely, Cage 4, prioritizing graft space with the largest window, demonstrated the lowest compressive strength, revealing a trade-off between graft window size and structural support. FEA findings aligned well with experimental results, showing consistent trends in load distribution. Cage 2 exhibited the lowest von Mises stress, while Cage 4 had the highest stress concentrations, indicating vulnerability to deformation. This consistency between FEA and experimental data validates the reliability of FEA in evaluating cage designs. The findings suggest that PLA/PCL cages are viable alternatives to conventional materials, advancing the development of sustainable, patient-specific spinal fusion solutions. This study emphasizes the critical role of design in achieving a balance between structural support and potential for effective graft support in spinal implants.