Accuracy and Safety in Pedicle Screw Placement in the Thoracic and Lumbar Spines : Comparison Study between Conventional C-Arm Fluoroscopy and Navigation Coupled with O-Arm® Guided Methods

Abstract

Objective: The authors performed a retrospective study to assess the accuracy and clinical benefits of a navigation coupled with O-arm® system guided method in the thoracic and lumbar spines by comparing with a C-arm fluoroscopy-guided method.

Methods: Under the navigation guidance, 106 pedicle screws inserted from T7 to S1 in 24 patients, and using the fluoroscopy guidance, 204 pedicle screws from T5 to S1 in 45 patients. The position of screws within the pedicle was classified into four groups, from grade 0 (no violation cortex) to 3 (more than 4 mm violation). The location of violated pedicle cortex was also assessed. Intra-operative parameters including time required for preparation of screwing procedure, times for screwing and the number of X-ray shot were assessed in each group.

Results: Grade 0 was observed in 186 (91.2%) screws of the fluoroscopy-guided group, and 99 (93.4%) of the navigation-guided group. Mean time required for inserting a screw was 3.8 minutes in the fluoroscopy-guided group, and 4.5 minutes in the navigation-guided group. Mean time required for preparation of screw placement was 4 minutes in the fluoroscopy-guided group, and 19 minutes in the navigation-guided group. The fluoroscopy-guided group required mean 8.9 times of X-ray shot for each screw placement.

Conclusion: The screw placement under the navigation-guidance coupled with O-arm® system appears to be more accurate and safer than that under the fluoroscopy guidance, although the preparation and screwing time for the navigation-guided surgery is longer than that for the fluoroscopy-guided surgery.

Keywords: Cervical spine injury; Cervical trauma; Interobserver agreement; Intraobserver reliability; Sub-axial injury classification scale.

Fig. 1

O-arm® system.

Fig. 2

Intraoperative photography showing the pedicle screw placement under the navigation guidance. Ideal entry point and trajectory of pedicle screws were defined by using a navigated pointer. Preparing entry point with awl, probing, tapping and screw placement were sequentially performed by using a guider set-up for navigation with a tracking arrayand following the information of multiplanar images on the navigation display.

Fig. 3

Bar graphs showing the distribution of the level operated in each group.

Fig. 4

Bar graphs showing mean preparation time for screw placement and screwing time in each group.