A Trajectory Close to the Anterolateral Vertebral Wall Becomes a Risk Factor for Intravascular Cement Leakage During Insertion of Cement-Augmented Fenestrated Pedicle Screws.

Objective: We aim to identify the characteristics and risk factors of intravascular cement leakage (CL) in cement-augmented fenestrated pedicle screw (CAFPS) insertion, particularly focusing on screw trajectory, bone density, and vertebral body volume.

Methods: A retrospective observational study was conducted on 41 patients who underwent spinal fixation surgery with CAFPS from June 2022 to November 2024. Intravascular cement leakage (CL) was assessed using postoperative computed tomography (CT) scans. The relationship between CL occurrence and parameters including age, sex, insertion level, volume of bone cement injected, lumbar spine bone density, order of bone cement injection, vertebral volume, and screw to vertebral wall distance (SVD) was investigated. Univariate and multivariate analyses were performed to identify risk factors for intravascular CL.

Results: The incidence of intravascular CL was observed in 29 out of 64 vertebrae (45.3%) and 37 out of 128 CAFPS (28.9%). Multivariate analysis identified SVD as a significant independent risk factor for intravascular CL occurrence (p < 0.001, odds ratio: 0.71, 95% confidence interval (CI): 0.58-0.87). Receiver operating characteristic (ROC) curve analysis determined a cutoff value of 9.96 mm for SVD to predict intravascular CL occurrence.

Conclusion: A lower screw to vertebral wall distance was identified as a risk factor for intravascular CL. To reduce the incidence of intravascular CL, a steeper medial trajectory for CAFPS insertion might be beneficial as it could potentially increase the distance between the screw and the anterolateral wall of the vertebral body. This study included 41 patients and was retrospective in design. While the cutoff value of 9.96 mm for SVD may assist surgical planning, the findings should be interpreted with caution due to the limited sample size and lack of long-term clinical outcome data.