Rates and Risk Factors of Intrapedicular Accuracy and Cranial Facet Joint Violation Among Robot- Assisted, Fluoroscopy-Guided Percutaneous, and Freehand Techniques in Pedicle Screw Fixation of Thoracolumbar Fractures: A Comparative Cohort Study

Background Robot-assisted (RA) technique has been increasingly applied in clinical practice, providing promising outcomes of inserting accuracy and cranial facet joint protection. However, studies comparing this novel method with other assisted methods are rare, and the controversy of the superiority between the insertion techniques remains. Thus, we compare the rates and risk factors of intrapedicular accuracy and cranial facet joint violation (FJV) of RA, fluoroscopy-guided percutaneous (FP), and freehand (FH) techniques in the treatment of thoracolumbar fractures. Methods A total of 90 patients with thoracolumbar fractures requiring pedicle screw instruments were retrospectively included and divided into RA, FP, and FH groups at 1:1:1 ratio from June 2016 to May 2020. The primary outcomes were the intrapedicular accuracy and cranial FJV. The factors that affected the intrapedicular accuracy and cranial FJV were assessed using multivariate analyses.Results The optimal intrapedicular accuracy of pedicle screw placement (Grade A) in the RA, FP, and FH groups was 94.3%, 79.3%, and 88.7%, respectively. This finding indicates no significant differences between RA and FH techniques (P =0.062), but significantly higher accuracies of RA over FP (P＜0.001), and FH over FP (P= 0.013). In addition, the rates of proximal FJV in RA, FP, and FH groups were 13.9%, 29.3%, and 22.7%, respectively. The RA had a significantly greater proportion of intact facet joints than the FP (P= 0.001) and FH (P= 0.035). However, FP and FH showed significantly similar outcomes with respect to the proximal FJV (P= 0.149). The logistic regression analysis showed that FP technique (OR= 2.791), pedicle angle (OR= 0.916), and L3 insertion (OR= 0.081) were independently associated with insertion accuracy. Meanwhile, the age (OR= 0.966), pedicle angle (OR= 0.940), mild facet joint osteoarthritis (OR= 5.906), moderate facet joint osteoarthritis (OR= 5.906), severe facet joint osteoarthritis (OR= 9.991), and distance from skin to insertion point (OR= 0.575) were independently associated with cranial FJV.Conclusion RA technique showed higher rate of intrapedicular accuracy and lower rate of cranial FJV than FH and FP techniques, and it might be a safe method for pedicle screw placement in thoracolumbar surgery.

The Relationship between Adjacent Segment Pathology and Facet Joint Violation by Pedicle Screw after Posterior Lumbar Instrumentation Surgery

Transpedicular screw instrumentation systems have been increasingly utilized during the fusion of lumbar spine procedures. The superior segment facet joint violation of the pedicle screw is thought to have potential for accelerating symptomatic adjacent-segment pathology (ASP). The purpose of this study was to investigate the relationship between the superior segment facet joint violation by transpedicular screws and the development of ASP. Among all patients who underwent operations involving one- or two-level posterior lumbar arthrodesis at the Chonnam National University Hospital from 1992 to 2012, 87 patients were selected for this study. Fifty-six patients were included in the ASP group, and 31 were included in the non-ASP group. We used lumbar three-dimensional computed tomography (CT) to assess the violation of the superior facet joint by a transpedicular screw. The assessment is presented in scores ranging from zero to two, with zero indicating no violation (type I); one point indicating suspected violation (type II); and two points indicating definitely facet joint violation (type III). Facet violation was reported in 31 patients in the ASP group (n = 56), and in 13 patients in the non-ASP group (n = 31). The types of facet joint violation according to our scoring system were as follows: type I, 59 screws (52.7%); type II, 26 screws (23.2%); and type III, 27 screws (24.1%) in the ASP group; and type I, 43 screws (69.4%), type II, 14 screws (22.6 %); and type III, 5 screws (8.0%) in the non-ASP group. The score of facet joint violation in each patient according to our scoring system were as follows: 0 points, 25 patients (44.6%); 1 point, 8 patients (14.3%); 2 points, 4 patients (7.1%); 3 points, 11 patients (19.7%); 4 points, 8 patients (14.3%) in the ASP group; and 0 points, 18 patients (58.1%); 1 point, 4 patients (12.9%); 2 points, 7 patients (22.6%); 3 points, 2 patients (6.4%); 4 points, 0 patients (0%) in the non-ASP group. The mean scores were 1.4 points in the ASP group and 0.8 points in the non-ASP group (p < 0.05). We conclude that the position of the pedicle screw farther away from the facet joint surface can reduce the degeneration of the superior adjacent segment. Therefore, close attention to the screw position during surgery may reduce the rate of superior adjacent-segment pathologies.

Clinical Validity of 3 Different Grading Systems for Facet Joint Violation: A Retrospective Study and In-Depth Review

Study Design: Retrospective. Objectives: To study the violation rate of 3 different types of facet joint violation (FJV) grading systems (Babu, Shah, and Park), and to evaluate the accuracy, reliability, and association with clinical outcomes of the above 3 grading systems. Methods: 152 patients of lumbar spinal stenosis treated with percutaneous pedicle screw placement were enrolled in our study. FJV was evaluated on 3-dimensional lumbar CT reconstruction. Three types of grading systems were used to evaluate FJV: Babu’s system (grading by the severity of violation), Shah’s system (grading by side of violation), and modified Park’s system (grading by different components to cause violation). The violation rate and observer consistency of the 3 grading systems were analyzed. Clinical outcomes were evaluated by visual analog score (VAS), Oswestry disability index (ODI) score. Results: Kappa coefficients of interobserver consistency on Babu, Shah, and Park grading systems were 0.726,0.849,0.692, respectively. The violation rate of Babu, Shah, and Park grading systems were comparable, which were 34.54%, 32.57%, 33.55%, respectively. In all 3 grading systems, the postoperative VAS low-back pain and ODI scores in non-FJV groups were lower than those in FJV groups ( P < .05), and there were no significant differences between 2 groups in VAS leg pain( P >.05). Conclusions: Babu, Shah and modified Park grading system are reliable grading systems, and it reported comparable violation rate. The self-reported clinical outcomes of patients with FJV were worse at 2-year follow-up. For clinical application, it is recommended to use 2 or even 3 different grading systems together to evaluate the FJV.