Accuracy of the pedicle screw insertion in upper cervical spine: a comparison between 3D O-arm based navigation and free-hand technique

English Keywords:Pedicle screw  Upper cervical  O-arm navigation  Accuracy

English Abstract:

  【Abstract】 Objectives: To compare the accuracy of pedicle screw insertion between three-dimensional(3D) O-arm based navigation and free-hand technique in upper cervical spine, and to explore the advantages of the O-arm based pedicle screw insertion. Methods: Sixty-two patients undergoing the upper cervical pedicle screw insertion in our institution were included and divided into two groups, the navigation group(group A) and free-hand group(group B). Group A consisted of 22 consecutive patients, including 15 males and 7 females with a mean age of 40.8±12.7 years(17-58 years), all patients underwent posterior upper cervical pedicle screw instrumentation based on intraoperative 3D navigation by using O-arm system between January 2014 and March 2015. Group B consisted of 40 patients(26 males and 14 females) received both free-hand C1 and C2 pedicle screw insertion from March 2005 to December 2013, all patients had an average age of 42.0±15.6 years(12-70 years). All patients undertook postoperative CT scans to assess the accuracy of cervical pedicle screw placement of each group and the differences between two groups were compared. The accuracy of pedicle screw insertions was classified into 4 grades according to Neo′s classification based on pedicle-wall perforations(grade 0, no perforation of the pedicle; grade 1, perforations ＜2mm, or ＜50% of screw diameter outside the pedicle; grade 2, perforations between ≥2mm and ＜4mm, or ﹥50% of screw diameter outside the pedicle; grade 3, perforations ＞4mm, or complete perforation). Results: Group A had 67 upper cervical pedicle screws being inserted(28 C1 pedicle screws and 39 C2 pedicle screws), 60(89.6%) of them were classified as grade 0, 7(10.4%) were grade 1, no grade 2 or grade 3 was identified. A total of 134 upper cervical pedicle screws were placed in group B(64 C1 pedicle screws and 70 C2 pedicle screws). 116(86.6%) of them were classified as grade 0, 13(9.7%) as grade 1, 4(3.0%) as grade 2, 1(0.7%) as grade 3. There was no statistical significance of the accuracy distribution of pedicle screw insertion and grade 0 screw placement between 2 groups(P=0.49 and P=0.55, respectively); moreover, the malposition of pedicle screws was identified in 3.7% screws of free-hand group, which was not found in navigation group, however, no significant difference was identified(P=0.17). No neurovascular complications related to pedicle screw insertion were noted in both groups. Conclusions: No significant difference of the accuracy in upper cervical pedicle screw insertion between O-arm navigation and free-hand group is found. Even clear intraoperative three-dimensional images can be provided by O-arm navigation, pedicle screw perforation cannot be completely prevented with this technology. Therefore, the interaction between the surgeon and navigation system should be improved and manipulation of O-arm navigation should be optimized to achieve more accuracy during pedicle screw placement.