The Frequency and Risk Factors for Cranial Facet Joint Violation during Pedicle Screw Instrumentation in Lumbar Spine Disorders

Background Data: Cranial facet joint violation (FJV) by pedicle screws may increase stress to the level adjacent to the instrumentation and may contribute to adjacent segment disease (ASD). Purpose: This study determines the frequency and risk factors for cranial FJV during pedicle screw instrumentation in various lumbar spine disorders. Study Design: A retrospective study. Patients and Methods: The data and imaging of adult patients with pedicle screw instrumentation for lumbar disorders from June 2018 to June 2021 were retrospectively reviewed for cranial FJV rate and evaluated for the role of the technique of instrumentation (conventional open or percutaneous), the facet angle (FA), the lumbar level, and the type of the disorder as risk factors for this violation. Preoperative Magnetic Resonance Imaging (MRI) was reviewed to measure the FA using T2 axial images. Postoperative Computed Tomography (CT) scans were examined to determine and grade cranial FJV. Results: The study included 360 patients. The overall FJV rate was 17.6%. The FJV rate significantly increased among the percutaneous fixation group compared to that of the open one (29.2% vs. 15.9%, respectively, p = 0.001). Patients with FJV had significantly larger FAs (p < 0.001). Moreover, patients with significantly larger FAs had higher grades of FJV (p value < 0.001). The FJV rate significantly increased with FAs > 40.12° (p < 0.001). L5 level and degenerative disease were more prone to FJV and higher grades of violation. Conclusion: The method of fixation, FA, lumbar level, and the type of lumbar disorder were the independent predictors of cranial FJV. This study reported a higher rate of FJV among patients with percutaneous fixation. The larger the FA, the higher the FJV rate and grade, especially with FAs > 40.12°, L5 level, and degenerative disease. (2021ESJ242)