Affiliations: [a] Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany | [b] Department of Orthopedic and Trauma Surgery, Marien Krankenhaus gGmbH, Bergisch Gladbach, Germany | [c] Department of Radiology, University Hospital of Düsseldorf, Düsseldorf, Germany | [d] Department of Spine Surgery, KLINIK am RING, Cologne, Germany
Correspondence:
[*]
Corresponding author: Jan Bredow, Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Kerpener Strasse 62, D-50937 Cologne, Germany. Tel.: +49 221 478-87294; Fax: +49 221 478-87296; E-mail:jan.bredow@uk-koeln.de
Note: [1] Equal contributors.
Abstract: 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.
