Methods: In this study, 64 patients who underwent EFJD were included. The main outcome of interest was patients’ Visual Analog Scale (VAS) pain score, which was recorded at 3-time points (i.e., before operation and 6 weeks and 12 months after surgery). Results: EFJD effectively reduced the VAS pain scores by 58% in the short term (6 weeks) and 38% in the long term (12 months). Patients with isolated facet joint osteoarthritis benefited more (p <0.001). Conclusions EFJD is a good treatment alternative for CLBP originating from the facet joints, particularly in patients with isolated facet joint osteoarthritis. Moreover, this method can address not only the dorsal medial ramus but also the surrounding tissue (e.g., facet joint capsule, facet joint effusion, and osteophytes) as the origin of CLBP.

Methods: The insertion angles of 87 pedicle screws inserted using CT-based navigation in the subaxial cervical spine were measured in the postoperative CT. The screw positioning was determined according to the modified Gertzbein and Robbins classification. Results: Total 89.3% (n=78) of the pedicle screws inserted using CT-based navigation showed good placement. The mean insertion angle of the pedicle screws that showed good positioning was 29.9°±9.9°. The pedicle screws showing bad positioning had a mean insertion angle of 26.8°±10.5° (p=0.157). The interobserver reliability showed a reliable measurement intraclass correlation coefficient: 0.994 (95% confidence interval, 0.992–0.996). Conclusions The present results show that the insertion angle of the pedicle screws in the subaxial cervical spine was smaller than the actual pedicle transverse angle, as per the literature. One reason for this discrepancy could be that the navigation systems allow the insertion of cervical pedicle screws with a lower convergence.