Accuracy of Pedicle Screw Placement in Dystrophic Neurofibromatosis Scoliosis: A Comparison between Free-Hand and 3D O-Arm Navigation Technique

Abstract

Introduction Recently, the importance of intraoperative navigation in scoliosis surgery has been increasing. Multiple studies have proven the superiorities of computer-assisted scoliosis surgery. Using intraoperative 3D images for navigational purposes has several advantages and should increase the accuracy and safety of pedicle screw placement. The purpose of the present study was to assess the accuracy of O-arm navigation-based pedicle screw insertion in dystrophic neurofibromatosis scoliosis and compare it with free-hand pedicle screw insertion technique. Patients and Methods A total of 32 patients with dystrophic neurofibromatosis scoliosis were nonrandomly included in the two groups, one consisting of O-arm navigation-based pedicle screw insertion (13 patients, Group A) and the other with free-hand technique (19 patients, Group B). A total of 213 pedicle screws were placed in apical region, 92 pedicles were inserted assisted by O-arm navigation system and the rest were inserted by free-hand technique. The postoperative CT scan image were reviewed and analyzed for pedicle violation. The screw penetration was divided into the following four grades: grade 0 (ideal placement), grade 1 (penetration < 2 mm), grade 2 (penetration between 2 and 4 mm), grade 3 (penetration > 4 mm). Results The mean age in group A was 14.8 years (range,11–22 years), whereas in group B was 15.3 years (range, 6–30 years). The preoperative Cobb angle of the main curve in group A was 70.3 ± 6.7 degrees compared with 62.2 ± 8.7 degrees in group B. The correction rates were comparable between group A (75.7%) and group B (78.1%), and the difference was not statistically significant ( p > 0.05). The overall perforation rate was 27.7% (59/213) in all 32 patients, and group A had a perforation rate of 20.7% (19/92) in comparison to 33.1% (40/121) noted in group B ( p < 0.05, χ2 test) separately. Moreover, the lateral margin was the most common site of perforation for 73.4% (14/19) in group A and 50.0% (20/40) in group B. Conclusion O-arm navigation does provide superiority over conventional free-hand technique in terms of accuracy of pedicle screw insertion in dystrophic curves associated with neurofibromatosis type 1. The lateral cortex is the most common site of screw perforation in either technique.