Patient-Specific Finite Element Models of Posterior Pedicle Screw Fixation: Effect of Screw’s Size and Geometry

Pedicle screw fixation is extensively performed to treat spine injuries or diseases and it common for thoracolumbar fractures. Post-operative complications may arise from this surgery leading back pain revisions. Finite element (FE) models could be used predict the outcomes of surgeries but should verified when both simplified realistic designs screws are used. The aim study was generate patient-specific Computed Tomography (CT)-based FE human vertebrae with two pedicle screws, verify models, use them evaluate effect screws’ size geometry on mechanical properties screws-vertebra structure. lumbar vertebra implanted were created anonymized CT-scans three patients. Compressive loads applied head screws. mesh optimized a refinement study. Finally, optimal sensitivity model changes in screw’s (diameter length) (realistic simplified). For sizes 0.6 mm 1.0 bone allowed obtain relative differences approximately 5% lower. Changes length resulted 4–10% maximum deflection, 1–6% peak stress 10–22% mean strain around screw; diameter 28–36% 6–27% 30–47% screw. deflection predicted correlated very well ( R 2 = 0.99). design 0.82) underestimated stress. In conclusion, results showed that has major role mechanics screw-vertebral structure each patient. Simplified can estimate vertebrae, systematic underestimation considered interpreting analyses.