title: Vertebral rotation during pedicle screw insertion in patients with cervical injury.
abstract: BACKGROUND
  Cervical pedicle screws, when misplaced, tend to perforate laterally. One of the reasons for lateral perforation is vertebral rotation during screw insertion. However, actual vertebral rotation during pedicle screw insertion is unknown. In this study, we measured vertebral rotation during pedicle screw insertion in patients with cervical injury.
  
  
  METHODS
  We inserted 76 pedicle screws into 38 vertebrae (C2 to C7) in 17 patients. All patients had some type of cervical injury. Screws were placed using intraoperative acquisition of data acquired with the isocentric C-arm fluoroscope (Iso-C3D) and computer navigation. We made screw holes using an image-guided awl, and we took images of cervical vertebrae in the neutral and rotational positions using navigation. Images of 76 insertions and rotational positions were taken while each cervical vertebra was under maximum stress at the time we were making the pedicle hole by awl.
  
  
  RESULTS
  Average cervical vertebra rotation was 10.6 degrees (range 6 to 17) at C2, 9.1 degrees (5 to 13) at C3, 7.8 degrees (6 to 9) at C4, 6.7 degrees (4 to 11) at C5, 4.9 degrees (2 to 8) at C6, and 2.8 degrees (0 to 4) at C7. Vertebrae in the upper and middle cervical spine rotated more than the lower cervical spine vertebrae. Of the 76 pedicle screws inserted into vertebrae between C2 and C7, 74 screws (97.4%) were classified as grade 1 (no pedicle perforation).
  
  
  CONCLUSIONS
  In this study, upper and middle cervical vertebrae in patients with neck injuries rotated more than the lower vertebrae. We should be especially careful of cervical rotation during screw insertion from C2 to C6, so as to prevent vertebral artery injury.
authors.affiliation: Department of Orthopaedic Surgery, Kobe Red Cross Hospital, Kobe City, Japan. yoshihisa64@hotmail.com
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ito
authors.forename: Masao
authors.initials: M
authors.lastname: Tomioka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimokawa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shiozaki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Mazaki
authors.forename: Masato
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws / Q000009:adverse effects* / Q000592:standards; D002574:Cervical Vertebrae / Q000033:anatomy & histology / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology* / Q000503:physiopathology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D012399:Rotation / Q000009:adverse effects; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D014711:Vertebral Artery / Q000033:anatomy & histology / Q000293:injuries / Q000601:surgery; D055815:Young Adult