Evaluation of pedicle screw accuracy and deviation from preoperative planning in intraoperative Cone-Beam Computed Tomography-Navigated lumbar spinal fusion: a prospective study.

Introduction: Preoperative planning using navigation systems allows the surgeon to optimize pedicle screw placement, minimizing the risk of misplacement. Research question: This study aimed to assess the accuracy of pedicle screws placement, and the deviation of final position compared to preoperative planning using Cone-Beam Computed Tomography (CBCT) navigation system. Material and methods: A prospective observational study was conducted on patients who underwent lumbar spinal fusion with TLIF technique for degenerative spondylolisthesis using intraoperative imaging navigation system. Accuracy and superior facet joint violation (FJV) were assessed following Gertzbein and Robbins system (GRS) and Yson classification, respectively. Deviation from planning was calculated by linear, angular and 3D deviations between planned and implanted screws. The comparison of continuous variables by GRS was performed by ANOVA followed by Bonferroni's test. The association between vertebral level and screw deviations was evaluated using ANOVA analysis. Results: The study included 40 patients with a mean age of 62.8 years. Of 180 pedicle screws implanted, 177 (98.30%) were clinically acceptable (GRS A + B) and 97.50% were classified as Yson grade 0. ANOVA reported statistically significant results between GRS and tip deviations in lateral-medial (p = 0.005), antero-posterior (p = 0.01) and 3D (p = 0.003), and between GRS and head deviations in antero-posterior and 3D (p < 0.001). ANOVA demonstrated statistically significant results between vertebral level and accuracy (p < 0.001). Discussion and conclusion: The intraoperatively acquired image navigation system showed high accuracy. Screw deviation proved the guiding function of planning during screw insertion and demonstrated that for slight deviations no decrease in accuracy was found.