Introduction: The pedicle screws technique (PST) in cervical spine offers superior biomechanical stabilization (ref). To maximize surgical precision the image guided (IG) technique was used. The goal of this report was to review the safety and accuracy of navigated cervical pedicle screws in patients treated with this method

Methods: 45 patients (32 male and 13 female) were selectively treated with PST. CT multiplanar reconstruction imaging (CTMPR) was used to generate multiple views orthogonal to the long axis of the bone target (see image). The screw/pedicle mismatch is defined as minimal diameter of targeted pedicle being smaller then an outer screw diameter (4.0 mm). The positions 118 cervical subaxial screws and the size of targeted pedicles (C3: 34, C4: 28, C5: 28, C6: 28) were retrospectively analyzed on pre- and post- images using CTMPR with orthogonal view in every case. The grading was: I- no breech, Ia- breech limited to outer screw diameter (ie screw thread), II-breech exceeding outer screw diameter, III-breech with neurovascular injury

Results: There were two postoperative complications with right C6 radiculopathies. First due to screw placement, which was successfully revised and second unrelated to screw position. The both patients improved during follow-up. There was one grade III screw, which was adjusted. The 56% (67/118) were acceptable screws (I-Ia). Grade II screws were in 43% (51/118). 16 screws were placed with screw/pedicle mismatch. The precision of screw placement was 70% (83/118) when pedicle morphology was taken into account. The grade II screws without pedicle/screw mismatch were consider navigation failures but not clinical failures.

Conclusions: The subaxial pedicle screw technique appears to be safe technique with its biomechanical superiority. The CTMPR with orthogonal view method is very efficient tool for screw placement evaluation. The IG seems to improve the placement precision but needs to be validated in a larger study

Patient Care: By evaluating safety and precision of pedicle screws placement technique in subaxial cervical spine our research contributes in popularization of this technique and its unique and superior biomechanical applications

Learning Objectives: Safety and accuracy of new surgical techniques which provides with superior biomechanical features

References: Johnston TL, Karaikovic EE, Lautenschlager EP, Marcu D: Cervical pedicle screws vs. lateral mass screws: uniplanar fatigue analysis and residual pullout strengths. Spine J 6:667-672, 2006