Related Experiment Video
Updated: Mar 16, 2026
Pedicle Screw Placement Using an Augmented Reality Head-Mounted Display in a Porcine Model
Published on: May 24, 2024
A novel classification of screw placement accuracy in the cervical spine
J Bredow1,1, F Beyer2,1, J Oppermann1
1Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
Background:
Goal of this study is to present an easily reproducible and reliable measurement to evaluate accuracy of screw placement in cervical spine.
Methods:
Accuracy of cervical screw position was assessed in 52 patients treated with 163 screws. Each patient receiving pedicle, transarticular C1/2, lateral mass, or laminar screws and postoperative CT scan was included. Placement position was categorized in 5 grades: Grade 1 is ideal with pedicle wall perforation < 1 mm, grade 2 < 2 mm, grade 3 < 3 mm, and grade 4 < 4 mm. Grade 5 > 4 mm and/or obstruction of transverse foramen by more than half a screw diameter. Intraclass correlation coefficient (ICC) values were assessed for inter- and intraobserver reliability.
Results:
The mode of individual evaluations was calculated to assign a single value to each screw. This yielded 89 grade 1 (54.6%), 48 grade 2 (29.4%), 14 grade 3 (8.6%), 3 grade 4 (1.8%), and 9 grade 5 (5.5%) screws. Intraobserver reliability ICC was 0.966 and 0.959 for measurements. Interobserver reliability ICC was 0.938.
Conclusion:
This study introduces a reliable classification of cervical spine instrumentation with various screw types. This should enable the use of a uniform and reproducible, and thus comparable classification for screw position in cervical spine.
