Randomized clinical study to compare the accuracy of navigated and non-navigated thoracic pedicle screws in deformity correction surgeries

Study Design. Randomized clinical trial ( level I evidence). Objective. To compare the accuracy of non-navigation and Iso-C based navigation in pedicle screw fixation in thoracic spine deformities. Summary of Background Data. Thoracic pedicle screw insertion for spinal deformity correction can be associated with increased pedicle breaches. Iso-C based navigation has been reported to improve the accuracy of pedicle screw placement, but its use in the presence of deformity has not been reported. Methods. Twenty-seven patients with scoliosis and 6 patients with kyphosis had a total of 478 thoracic pedicle screws. The average Cobb angle was 58.4 degrees +/- 8 degrees (range 50 degrees-80 degrees), and the mean kyphotic angle was 54.6 degrees +/- 4 degrees (range 51 degrees-76 degrees). By random allocation, 17 patients had screw insertion under navigation ( 242 screws) and 16 under fluoroscopic control ( 236 screws). The 2 groups were compared for accuracy of screw placement, time for screw insertion, and the number of times the C-arm had to be brought into the field. Two independent blinded observers determined accuracy using postoperative computed tomography assessments. Results. There were 54 (23%) pedicle breaches in the non-navigation group as compared to only 5 (2%) in the navigation group (P < 0.001). Thirty-eight screws (16%) in the non-navigation group had penetrated the anterior or lateral cortex compared to 2 screws (0.8%) in the navigation group. Average screw insertion time in the non-navigation group was 4.61 +/- 1.05 minutes (range 1.8-6.5) compared to 2.37 +/- 0.72 minutes ( range 1.16-4.5) in navigation group (P < 0.01). The C-arm had to be moved into the operation field on an average of 1.5 +/- 0.25 times (range 1-3) per screw. With single screening data, an average of 11.4 pedicles (range 9-14) could be visualized without necessity to bring the C-arm into operating field again. Conclusions. Iso-C navigation increases accuracy, and reduces surgical time and radiation in thoracic deformity correction surgeries.