LAUSR

Study Design. An observational cohort study. Objective. The aim of this study was to compare the rate of pedicle perforation while inserting screws (PS) using O-arm navigation during surgery for scoliosis with that reported previously and to determine the risk factors specific to O-arm navigation. Summary of Background Data. O-arm navigation provides intraoperative three-dimensional fluoroscopic imaging with an image quality similar to that of computed tomography. Surgeons have started using O-arm navigation in treatment of adolescent idiopathic sclerosis (AIS). However, there are few reports of the perforation rate when using O-arm navigation to insert pedicle screws for AIS. To our knowledge, no information has been published regarding risk factors for pedicle perforation by PS when using O-arm navigation during surgery for AIS. Methods. We retrospectively reviewed the cases of 23 consecutive patients with AIS (all female; mean age 15.4 years, range 12–19 years) who had all undergone PS fixation under O-arm navigation. Results. There were 11 major pedicle perforations (Grade 2 or 3) by the 404 screws (2.7%). For both Grade 1 to 3 and Grade 2 or 3 perforations, the pedicle perforation rate by the ninth or subsequent screws was significantly higher than that for the other two groups (screws 1–4, 5–8) (P < 0.01). Grade 1 to 3, Grades 2 or 3, and Grade 3 perforation rates after a previous perforation were significantly higher than those in patients without a previous perforation (P < 0.01). The rate of screw deviation can increase significantly to 12.2% after insertion of 8. Conclusion. The rate of major perforation of pedicles after inserting PS using O-arm navigation during surgery for AIS is relatively low. However, we recommend caution using intraoperative navigation after inserting eight pedicle screws because after this, the trajectory deviation rate can increase significantly. Level of Evidence: 3