title: A novel classification of screw placement accuracy in the cervical spine.
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.
  
  
  CONCLUSIONS
  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.
authors: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.|Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: J
authors: J
authors: Bredow
authors: Department of Orthopedic and Trauma Surgery, Marien Krankenhaus gGmbH, Bergisch Gladbach, Germany.|Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: F
authors: F
authors: Beyer
authors: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: J
authors: J
authors: Oppermann
authors: Department of Radiology, University Hospital of Düsseldorf, Düsseldorf, Germany.
authors: B
authors: B
authors: Kraus
authors: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: C
authors: C
authors: Meyer
authors: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: G
authors: G
authors: Stein
authors: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors: P
authors: P
authors: Eysel
authors: Department of Spine Surgery, KLINIK am RING, Cologne, Germany.
authors: T
authors: T
authors: Koy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws / Q000145:classification* / Q000592:standards*; D002574:Cervical Vertebrae / Q000601:surgery*; D061827:Dimensional Measurement Accuracy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013123:Spinal Fusion / Q000379:methods* / Q000592:standards*; D055815:Young Adult
keywords: Classification; cervical spine; screw placement accuracy; spondylodesis