Accuracy of screw placement in the apical region of adolescent idiopathic scoliosis assisted by intraoperative navigation and calibration technology

English Keywords:Adolescent idiopathic scoliosis  Navigation  Pedicle screw  Morphology  Apical region

English Abstract:

  【Abstract】 Objectives: To compare the accuracy and deviation direction of screw placement in the same pedicle type of apical vertebra of adolescent idiopathic scoliosis(AIS) with the aid of navigation and navigation calibration techniques, and to analyze the influencing factors of screw displacement under navigation and the clinical significance of navigation calibration technique. Methods: From October 2017 to October 2020, 41 patients who were diagnosed with AIS in our hospital and were treated with posterior correction and internal fixation for scoliosis under the guidance of navigation were retrospectively analyzed. The patients were divided into navigation group(n=22) and navigation calibration group(n=19) according to whether applied navigation calibration technique. The basic information of the two groups of patients was collected, and the Risser sign, the Cobb angles before and after operation, and the postoperative correction rate were recorded. The types of pedicles of apical vertebrae of patients were classified according to the classification standard of Fu Changfeng(A, B, C, D, E), and the accuracy of screw placement of the same pedicle type was evaluated according to Rao classification. Results: The excellent and good screw placement rates of types A, B, and C pedicles in the navigation calibration group were 96.4%, 87.8%, and 84.0%, which were significantly higher than those in the navigation group of 79.2%, 70.5%, and 56.7% respectively, and the rates of grade 0 screws on both sides of the concave and convex in navigation calibration group was also significantly higher. The rates of grade 3 screw placement of B-type pedicle and its concave and convex bilateral sides in the calibration group and navigation group were respectively 4.1% and 12.4%, 2.0% and 11.1%, 6.3% and 13.7%, and the grade 2 screw rate of convex side of C-type pedicle was 11.1% and 50.0%, and the differences between the two groups were statistically significant(P<0.05). In addition, the perforation rates of the lateral cortex of types A, B, and C pedicles in the navigation calibration group were 33.3%, 33.3%, and 60.0%, which were significantly lower than those in the navigation group of 64.0%, 38.6%, and 73.1%. Meanwhile, in navigation calibration group, the anterior wall perforation rate of A-type pedicle was 0.0% and the perforation rate of the lateral cortex of the concave side of C-type pedicle was 66.7%, which were significantly lower than those of the navigation group of 24.0% and 77.8%. The perforation rate of the medial cortex of the B-type pedicle in navigation calibration group was 41.7%, which was higher than that in the navigation group of 40.9%, but the perforation rate of the concave medial cortex of 36.4% was significantly lower than 33.3% of the navigation group, and the differences between the two groups were statistically significant(P<0.05). None patients in both groups occurred serious complications such as spinal cord and neurovascular injury. Conclusions: Comparing with traditional navigation, the navigation calibration technology can effectively prevent navigation deviation during operation, improve significantly the accuracy of screw placement in types A, B, and C pedicles of AIS apical vertebrae, and reduce the perforation rates of lateral wall and concave medial wall of type B pedicle by screw misplacement, which may improve the safety of operation.