Risk Factors for Cement Leakage into Segmental Veins during Posterior Spinal Fusion Using Fenestrated Pedicle Screws

Introduction: Although fenestrated screws enhance pull-out strength, cement leakage into segmental veins carries a risk of pulmonary embolism. This study aimed to identify factors that contribute to cement leakage during posterior spinal fusion with fenestrated screws. Methods: We conducted a retrospective analysis of 32 patients who underwent posterior spinal fusion with fenestrated pedicle screws. A total of 147 screws were evaluated using postoperative computed tomography (CT) scans. Risk factors were assessed by measuring vertebral CT values, the volume of injected cement and its ratio to vertebral body volume, and screw positioning parameters, including deviation and distance to the anterior and lateral walls. Results: Cement leakage occurred in 75% of patients (24 of 32) and in 35% of screws (52 of 147). All leakages were classified as leakage into segmental veins. No symptomatic pulmonary embolism was observed. The thoracic spine exhibited a higher leakage rate than the lumbar spine (47.5% vs. 28.4%, p