Design and fabrication of a lumbar spine simulator for fluoroscopy-guided intervertebral disk puncture

Fluoroscopy-guided spinal interventions require anatomically representative and radiographically compatible physical models for procedural simulation. Cadaveric specimens and animal models, while valuable, are limited by cost, availability, ethical considerations, and restricted repeatability. These limitations motivate the development of cost-efficient lumbar spine simulators compatible with C-arm fluoroscopic imaging. Vertebrae and pelvic structures were generated from open-source STL files and fabricated using fused deposition modeling. Post-processing included surface polishing and fabrication of silicone molds to reproduce vertebral geometry. Combinations of two-component polyurethane casting resin, calcium sulfate, barium sulfate, and iohexol were tested to evaluate radiographic visibility and identify a suitable radiopaque formulation. Vertebral elements were assembled using silicone interfaces to form puncturable intervertebral spaces. Soft tissues and skin were imitated using gelatin-glycerin foam and pigmented silicone. Radiographic appearance was assessed under C-arm fluoroscopy. Among the tested formulations, polyurethane composite containing 5 wt% calcium sulfate provided sufficient radiographic visibility while avoiding excessive radiopacity and was selected for the final simulator. The simulator reproduced key lumbar anatomical features and enabled clear visualization of the needle trajectory under fluoroscopy. Design optimization produced a lighter and more compact configuration than the initial prototype. This study presents a reproducible 3D-printed lumbar spine simulator with tunable radiographic properties compatible with fluoroscopic imaging. The proposed design provides a cost-efficient physical model for image-guided procedural simulation and technical development, intended for non-commercial academic and educational use.