Clinical accuracy of three-dimensional fluoroscopy-based computer-assisted cervical pedicle screw placement: a retrospective comparative study of conventional versus computer-assisted cervical pedicle screw placement.

OBJECT

The authors performed a retrospective clinical study to evaluate the feasibility and accuracy of cervical pedicle screw (CPS) placement using 3D fluoroscopy-based navigation (3D FN).

METHODS

The study involved 62 consecutive patients undergoing posterior stabilization of the cervical spine between 2003 and 2008. Thirty patients (126 screws) were treated using conventional techniques (CVTs) with a lateral fluoroscopic view, whereas 32 patients (150 screws) were treated using 3D FN. Screw positions were classified into 4 grades based on the pedicle wall perforations observed on postoperative CT.

RESULTS

The prevalence of perforations in the CVT group was 27% (34 screws): 92 (73.0%), 12 (9.5%), 6 (4.8%), and 16 (12.7%) for Grade 0 (no perforation), Grade 1 (perforation < 1 mm), Grade 2 (perforation ≥ 1 and < 2 mm), and Grade 3 (perforation ≥ 2 mm), respectively. In the 3D FN group, the prevalence of perforations was 18.7% (28 screws): 122 (81.3%), 17 (11.3%), 6 (4%), and 5 (3.3%) for Grades 0, 1, 2, and 3, respectively. Statistical analysis showed no significant difference in the prevalence of Grade 1 or higher perforations between the CVT and 3D FN groups. A higher prevalence of malpositioned CPSs was seen in Grade 2 or higher (17.5% vs 7.3%, p < 0.05) in the 3D FN group and Grade 3 (12.7% vs 7.3%, p < 0.05) perforations in the CVT group. The ORs for CPS malpositioning in the CVT group were 2.72 (95% CI 1.16-6.39) in Grade 2 or higher perforations and 3.89 (95% CI 1.26-12.02) in Grade 3 perforations.

CONCLUSIONS

Three-dimensional fluoroscopy-based navigation can improve the accuracy of CPS insertion; however, severe CPS malpositioning that causes injury to the vertebral artery or neurological complications can occur even with 3D FN. Advanced techniques for the insertion of CPSs and the use of modified insertion devices can reduce the risk of a malpositioned CPS and provide increased safety.