gms | German Medical Science

Objective: iCT Navigation is far and wide the most expensive way to control the proper screw placement. Aim of this study is to prove its effectiveness comparing to other methods to control the spinal screw placement accuracy.

Methods: This retrospective study is focusing on a group of 108 patients that underwent iCT navigated spinal stabilization surgery, with transpedicular screws inserted, between October 2015 and November 2017. Surgeries were performed by 8 different neurosurgeons or neurosurgical residents under supervision. In each surgery, an intraoperative CT scan for referencing the navigation was performed and subsequently one or more CT scans for intraoperative control of screw placement accuracy were performed.

Results: 108 patients (50 male, 58 female) with instability of different origin in all spinal regions: cervical (7), cervico-thoracal (4), thoracic (13), thoracic-lumbar (10), lumbar (54) and lumbosacral (20), were included in this study. 51 monosegmental and 57 multisegmental transpedicular screw stabilizations were indicated. We used a strict definition of suboptimal or improper screw placement: in case of each pedicle corticalis injury. Optimal screw placement after the first intraoperative CT control was detected in 77 patients (71,3%). In 31 patients (28,7%), there were suboptimal or improper placements detected, out of which 20 patients (18,5%) needed an intraoperative revision. The displacement was caused in most cases by medial (recessal) screw position (14,8%), following by lateral position (12%) and extra corporal screw position (11,1%). In the whole group, there was no neurovascular damage observed.

Conclusion: Our study shows that no secondary operation to revise the misplaced screws was required. Intraoperative revision rate with sharp criteria was 18,5% in our study. The decision level to revise a suboptimally inserted screw following intraoperative CT scan was significantly lower because no further surgical procedure was needed. After two years of iCT navigation use, we expect further reduction of the revision rate due to learning curve. Revision rate under fluoroscopic control varies in common literature resources from 5% up to 45%.