Introduction: The O-arm Multidimensional Surgical Imaging System provides superior accuracy of pedicle screw insertion compared to free-hand and fluoroscopic approaches. However, no studies have investigated the clinical relevance of increased accuracy. The objective of this study was to investigate the clinical outcomes following spinal fusion using O-arm navigation. We hypothesized that increased accuracy with O-arm navigation decreases the risk of reoperation compared with free-hand and fluoroscopic guidance.
Methods: A consecutive retrospective review of all patients undergoing non-cervical spinal fusion at a single tertiary-care institution between 12/2012 and 12/2014 was conducted. Multivariable linear and Cox proportional hazards regression were used to investigate the association between O-arm navigation and outcomes.
Results: Among 1,208 procedures, 614 were performed with O-arm navigation, 356 using free-hand techniques, and 238 using fluoroscopy. The most common indication for surgery was spondylolisthesis (56.2%), and most patients underwent posterolateral fusion (75.7%). The average fusion spanned 4.53 vertebral levels. O-arm patients experienced shorter hospital stays compared to free-hand and fluoroscopy approaches (4.72 days v. 5.07 days, p<0.01), and multivariable linear regression revealed O-arm as an independent predictor of shorter hospital stays compared to fluoroscopy (ß=0.50, p<0.01). O-arm was significantly associated with decreased risk of reoperation for hardware failure (2.9% v. 5.9%, RR 0.50, p=0.01), screw misplacement (1.6% v. 4.2%, RR 0.39, p<0.01), and all-cause reoperation (5.2% v. 10.9%, RR 0.48, p<0.01); these findings were corroborated with Kaplan-Meier survival analysis (Figure 1). Cox proportional hazards modeling revealed that O-arm navigation was an independent predictor of reoperation risk, as free-hand (HR 1.97, p<0.01) and fluoroscopic (HR 2.32, p<0.01) methods both predicted greater risk of reoperation.
Conclusions: This is the first study to investigate clinical outcomes associated with O-arm navigation following spinal fusion. O-arm navigation predicted decreased length of hospital stay and decreased the risk of reoperation to half the risk of free-hand and fluoroscopic approaches.
Patient Care: The long-term decreased risk of reoperation associated with O-arm navigation is a critical finding to establish the importance and benefit of intraoperative imaging. The present results suggest that O-arm usage decreases the risk of requiring reoperation by more than half compared to either free-hand of fluoroscopic method; thus, increased use of O-arm navigation could yield significantly improved long-term patient outcomes and represent a cost-effective modality.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the importance of O-arm navigation to improve pedicle screw accuracy and decrease the long-term risk of reoperation.
2) Discuss, in small groups, strategies to further decrease the risk of reoperation in addition to O-arm navigation.
3) Identify an effective treatment of degenerative spine conditions requiring spinal fusion, including approaches using O-arm navigation for superior pedicle screw accuracy.
References: 1. Gelalis ID, Paschos NK, Pakos EE, Politis AN, Arnaoutoglou CM, Karageorgos AC, et al.: Accuracy of pedicle screw placement: a systematic review of prospective in vivo studies comparing free hand, fluoroscopy guidance and navigation techniques. Eur Spine J 21:247–55, 2012.
2. Shin BJ, James AR, Njoku IU, Härtl R: Pedicle screw navigation: a systematic review and meta-analysis of perforation risk for computer-navigated versus freehand insertion. J Neurosurg Spine 17:113–22, 2012.
3. Oertel MF, Hobart J, Stein M, Schreiber V, Scharbrodt W: Clinical and methodological precision of spinal navigation assisted by 3D intraoperative O-arm radiographic imaging. J Neurosurg Spine 14:532–536, 2011.