title: The correlation between cervical range of motion and misplacement of cervical pedicle screws during cervical posterior spinal fixation surgery using a CT-based navigation system.
abstract: OBJECTIVE
  The aim of this study was to analyze the correlation between cervical range of motion and cervical pedicle screw (CPS) misplacement in cervical posterior spinal fusion surgery using a CT-based navigation system.
  
  
  METHODS
  A total of 46 consecutive patients with cervical posterior spinal fusion surgery using CPSs were evaluated retrospectively. We analyzed the cervical range of motion (ROM) and the misplacement of CPSs that were placed using either separate or single-time multilevel registration with a CT-based navigation system to determine the optimum registration procedure. The screw-inserted vertebra was indicated as Registered vertebra-Pedicle Screw inserted vertebra (Re-PS) = 0, 1, 2, or 3 depending on its distance (level) from the registered vertebra. Grades 0 (no perforation) and 1 (perforations <2 mm) were categorized as "no misplacement." Grades 2 (perforations ≧ 2 mm but < 4 mm) and 3 (perforations ≧ 4 mm) were categorized as "misplacement." We analyzed the correlations between CPS misplacement and Re-PS, and between CPS misplacement and preoperative cervical ROM.
  
  
  RESULTS
  Our analysis included 196 screws in patients having a mean age of 53.2 years (range 5-84 years). Level of insertion relative to registration was Re-PS = 0 in 129 screws, Re-PS = 1 in 53, Re-PS = 2 in 10 and Re-PS = 3 in 4. The misplacement rates were 12.2 % (24 screws) overall, 6.2 % in Re-PS = 0, 22.6 % in Re-PS = 1, 20 % in Re-PS = 2, and 50 % in Re-PS = 3. The rate of CPS misplacement increased significantly with a Re-PS = 1 and a Re-PS = 2 and 3 compared to a Re-PS = 0. There was a significant difference in the cervical ROM in each grade and both misplacement groups: 1.8 in Grade 0, 2.3 in Grade 1, 7.8 in Grade 2, 12.9 in Grade 3, 11 in the misplacement group and 1.9 in the no misplacement group.
  
  
  CONCLUSIONS
  The precision of CPS placement in CT-based navigation surgery was evaluated. The misplacement rate in single-time multilevel registration increased to 23.4 % compared to 6.2 % for separate registration. As the distance increased between the registered level and the level of CPS insertion, the preoperative cervical ROM and the rate of CPS misplacement significantly increased. Thus, the rate of misplacement of CPSs is reduced when performing separate registration. Furthermore, when there is greater preoperative cervical ROM, separate registration would likely improve the safety and accuracy of CPS insertion.
authors: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 4668550, Japan.
authors: Ryoji
authors: R
authors: Tauchi
authors: Shiro
authors: S
authors: Imagama
authors: Yoshihito
authors: Y
authors: Sakai
authors: Zenya
authors: Z
authors: Ito
authors: Kei
authors: K
authors: Ando
authors: Akio
authors: A
authors: Muramoto
authors: Hiroki
authors: H
authors: Matsui
authors: Tomohiro
authors: T
authors: Matsumoto
authors: Naoki
authors: N
authors: Ishiguro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws / Q000009:adverse effects*; D002574:Cervical Vertebrae / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed; D055815:Young Adult