The Rates and Risk Factors of Intra-Pedicular Accuracy and Proximal Facet Joint Violation for Single-Level Degenerative Lumbar Diseases Cortical Bone Trajectory Versus Traditional Trajectory Pedicle Screw

Study Design. A retrospective study. Objective. To compare the accuracy of pedicle screw placement and proximal facet joint violation (FJV) in single-level degenerative lumbar diseases using cortical bone trajectory (CBT) and traditional trajectory (TT) techniques, and analyze their possible risk factors. Summary of Background Data. CBT screws have been utilized increasingly to improve cortical bone contact to prevent screw pullout and reduce approach-related morbidity. However, the studies on intra-pedicular accuracy and proximal FJV between the two methods are rare. Methods. A total of 40 patients who required single-level instruments were included in the retrospective study treated with the CBT-TLIF and the TT-TLIF at a 1:1 ratio from March 2019 to August 2020. The radiographic outcomes were the intra-pedicular accuracy and proximal FJV. Moreover, the possible risk factors were assessed using bivariate and multivariate analyses. Results. As for the intra-pedicular accuracy, 73 screws (91.3%) were classified as grade A, 7 screws (8.7%) classified as grade B in the CBT group. A total of 71 screws (88.8%) were graded A with remaining 8 screws (10.0%) graded B and 1 screw (1.2%) graded C in the TT group. The proportion of optimal and clinically acceptable screw positions in the two groups were not significantly different (P> 0.05). In addition, the rate of proximal FJV in CBT approach (8.3%) was significantly lower than that in the TT approach (35.0%) (P< 0.001). Multivariate analysis showed the TT insertion approach and facet angle >= 45 degrees were the independent risk factors for proximal FJV, but no factors above affected intra-pedicular accuracy. Conclusion. Compared with the TT approach in TLIF, the CBT approach showed similar intra-pedicular accuracy and remarkable superiority in proximal facet joint protection. Facet angle >= 45 degrees is the independent risk factors for proximal FJV.