The Efficacy and Accuracy of Cone Beam CT (O-Arm) Navigation (StealthStation) on Screw Position in Adult Scoliosis Surgery

Abstract

Introduction Intraoperative CT and navigation systems may provide an opportunity to improve precision and accuracy of pedicle screw placement, and in so doing, improve patient outcomes. Adult spinal deformity provides unique anatomical challenges potentially amenable to spinal navigation. Our study aimed to examine the efficacy and safety of intraoperative cone beam CT navigation for pedicle screw placement in complex spinal deformity cases. Material and Methods We identified all patients treated at our institution with spinal fusion for the primary diagnosis of major adult deformity between January 2008 and December 2012 in whom O-arm and StealthStation navigation was used (NAV). A historic control cohort (non-NAV) was matched based on age, number of levels, curve type and size, and previous fusion. The number and timing (intraoperative, early symptomatic postoperative, late symptomatic postoperative, and incidental) of screw malposition and the need for revision screw placement were recorded. All patients had a minimum follow-up of 1 year. Any screw with pedicle breach greater than 0 mm was recorded as misplaced. The direction and anatomical level of misplaced screws were also determined. Quantitative statistical analysis compared screw placement between NAV and non-NAV cases. Results A total of 56 patients met the inclusion criteria in both cohorts (112 patients). The mean number of screws placed in each group was not significantly different (17.29 in NAV and 17.71 in non-NAV, p = 0.75). Thirty-eight (34%) patients in the non-NAV group had misplaced screws compared with 21 (19%) in the NAV group ( p = 0.002). The detection of incidental screw malposition was significantly higher in the non-NAV cases (44.6 vs. 23.2%, p < 0.05) and the need for intraoperative screw revision favored navigation ( p < 0.03). Six cervical screws, 16 cervicothoracic, 90 thoracic, and 112 lumbar screws were placed. Early postoperative screw revision rates approached significance ( p < 0.06) favoring navigation. The number of adverse events and length of stay (mean 17 vs. 20.4 days in NAV and non-NAV groups, respectively) were not significantly different. The mean number of postoperative CT scans was significantly fewer in the NAV group (9 vs. 22 in non-NAV group, p = 0.004), while mean OR time was statistically different between groups (492 minutes in the NAV group vs. 408 minutes in the non-NAV, p = 0.002). Conclusion Our results demonstrate that intraoperative CT-guided navigation provides an equally safe and more accurate and precise tool for pedicle screw placement than traditional techniques in adult spinal deformity surgery. There were more intraoperative screws adjusted and fewer postoperative screws revised with NAV. Far fewer patients required postoperative CT examination with the use of NAV.