Accurate Placement and Revisions for Cervical Pedicle Screws Placed With or Without Navigation: A Systematic Review and Meta-Analysis

Study Design Systematic review and meta-analysis. Objectives To evaluate the accuracy of placement for cervical pedicle screws with and without the use of spinal navigation. Methods A structured search was conducted in electronic databases without any language or date restrictions. Eligible studies reported the proportion of accurately placed cervical pedicle screws measured on intraoperative or postoperative 3D imaging, and reported whether intraoperative navigation was used during screw placement. Randomized Studies (MINORS) criteria were used to evaluate the methodological quality of how accuracy was assessed for cervical pedicle screws. Results After screening and critical appraisal, 4697 cervical pedicle screws from 18 studies were included in the meta-analysis. The pooled proportion for cervical pedicle screws with a breach up to 2 mm was 94% for navigated screws and did not differ from the pooled proportion for non-navigated screws (96%). The pooled proportion for cervical pedicle screws placed completely in the pedicle was 76% for navigated screws and did not differ from the pooled proportion for non-navigated screws (82%). Intraoperative screw reposition rates and screw revision rates as a result of postoperative imaging also did not differ between navigated and non-navigated screw placement. Conclusions This systematic review and meta-analysis found that the use of spinal navigation systems does not significantly improve the accuracy of placement of cervical pedicle screws compared to screws placed without navigation. Future studies evaluating intraoperative navigation for cervical pedicle screw placement should focus on the learning curve, postoperative complications, and the complexity of surgical cases.

Supplement 5. Accuracy of placement for the axial spine (C1-C2) and subaxial cervical spine (C3-C7) of the 18 included studies in the meta-analyses.

Axial spine (C1-C2)
Eight studies placed navigated pedicle screws in C1-C2, and six reported the accuracy of placement separately.The six studies placed 287 pedicle screws and reported 84-100% of the screws to be completely in the pedicle or with a minor breach.One study did not separately report the number of screws completely in the pedicle.For the remaining 241 screws, 63-96% were reported to be completely in the pedicle.Seven studies placed non-navigated pedicle screws in C1-C2, and all reported the accuracy of placement separately.In total, 439 pedicle screws were placed, of which 89-98% were reported to be completely in the pedicle or having a minor breach.One study did not separately report the number of screws placed completely in the pedicle.For the remaining 417 pedicle screws, 62-83% were reported to be completely in the pedicle.

Subaxial cervical spine (C3-C7)
Eight studies placed navigated pedicle screws in C3-C7, and six reported the accuracy of placement separately.The six studies placed 536 pedicle screws and reported 78-100% of the screws to be completely in the pedicle or with a minor breach.One study did not separately report the number of screws completely in the pedicle.For the remaining 344 screws, 42-97% were reported to be completely in the pedicle.Seven studies placed non-navigated pedicle screws in C3-C7, and all reported the accuracy of placement separately.In total, 3103 pedicle screws were placed, of which 55-100% were reported to be completely in the pedicle or having a minor breach.One study did not separately report the number of screws placed completely in the pedicle.For the remaining 3056 pedicle screws, 50-88% were reported to be completely in the pedicle.

Unbiased assessment of the study endpoint: blind
3. Prospective collection of data: data were collected according to a protocol established before the beginning of the study 0 -not reported 1 -reported but inadequate -> retrospective study 2 -reported and adequate -> prospective study 4. Endpoints appropriate to the aim of the study: unambiguous explanation of the criteria used to evaluate the main outcome which should be in accordance with the question addressed by the study.Also, the endpoints should be assessed on an intention-to-treat basis.0 -not reported 1 -reported but inadequate -> accuracy assessed on other image than CT or CBCT 2 -reported and adequate -> accuracy assessed on intraoperative or postoperative CT or CBCT 5. evaluation of objective endpoints and doubleblind evaluation of subjective endpoints.Otherwise the reasons for not blinding should be stated 0 -not reported-> unclear who assessed the accuracy of placement 1 -reported but inadequate -> someone involved in the surgery assessed the accuracy of placement 2 -reported and adequate -> accuracy of placement was assessed by at least one

. Prospective calculation of the study size: information
2 -reported and adequate10.Contemporary groups: control and studied group should be managed during the same time period (no historical comparison) 0 -not reported 1 -reported but inadequate -> case-control studies 2 -reported and adequate -> observational studies 11.Baseline equivalence of groups: the groups should be similar regarding the criteria other than the studied endpoints.Absence of confounding factors that could bias the interpretation of the results 0 -not reported 1 -reported but inadequate 2 -reported and adequate 12. Adequate statistical analyses: whether the statistics were in accordance with the type of study with calculation of confidence intervals or relative risk 0 -not reported 1 -reported but inadequate 2 -reported and adequate *Only studies that directly compared navigated cervical pedicle screw placement to screw placement without navigation were critically appraised as comparative studies.Supplement 3. Screw details and accuracy for all 67 included studies

Screw insertion method Total number of screws (% screws completely in the pedicle or with breach < 2mm)
Supplement 4. .The Methodological Index for Non-Randomized Studies (MINORS) criteria for all 67 included studies *Number of all patients included in the study, the number of patients specifically undergoing cervical pedicle screw insertion was not reported separately, **Numbers reported for all patients included in the study (including numbers for other screws than cervical pedicle screws).Abbreviations: FH = free-hand, NAV = navigated, NON = non-navigated, NR = not reported, RB = robotic