Purpose <p>Research into the spinal biomechanics of 3D-printed porous titanium pedicle screws (3DPS) has not yet been undertaken. This study evaluates the structural performance of 3DPS under physiological loading conditions using finite element analysis (FEA) and analyzes the effects of varying porosity levels on their mechanical behavior.</p> Method <p>A validated FE model of the lumbar spine was used to simulate one-, two-, and three-level fusion scenarios with 3DPS and transforaminal lumbar interbody fusion (TLIF) cages. Physiological loads, including flexion, extension, lateral bending, and axial rotation, were applied. Peak von Mises stress (PVMS), stress distribution, and structural stability were assessed across the different porosity configurations (0%, 60%, 70%, and 80%).</p> Result <p>The PVMS value in the core increases as the porosity increases. the stress distribution of posterior fixations in a 3-level fusion. when the porosity of the porous layer was 80%, the stress was concentrated in the core. At 70% and 80% porosity, where the risk of structural instability exceeded safe thresholds under a conservative safety factor of 3. The 60% porosity demonstrated an optimal balance between mechanical stability and stress distribution.</p> Conclusion <p>3DPS, particularly those with 60% porosity, offer promising potential for enhancing fixation stability. Further studies are needed to confirm their long-term clinical efficacy. The outcomes of this research offer a critical preliminary step for preclinical and clinical evaluations aimed at confirming the mechanical integrity of 3D-printed porous structures.</p>