title: Morphometric evaluation of subaxial cervical spine using multi-detector computerized tomography (MD-CT) scan: the consideration for cervical pedicle screws fixation.
abstract: BACKGROUND
  Cervical pedicle screw (CPS) insertion is a technically demanding procedure. The quantitative understanding of cervical pedicle morphology, especially the narrowest part of cervical pedicle or isthmus, would minimize the risk of catastrophic damage to surrounding neurovascular structures and improve surgical outcome. The aim of this study was to investigate morphology and quantify cortical thickness of the cervical isthmus by using Multi-detector Computerized Tomography (MD-CT) scan.
  
  
  METHODS
  The cervical CT scans were performed in 74 patients (37 males and 37 females) with 1-mm slice thickness and then retro-reconstructed into sagittal and coronal planes to measure various cervical parameters as follows: outer pedicle width (OPW), inner pedicle width (IPW), outer pedicle height (OPH), inner pedicle height (IPH), pedicle cortical thickness, pedicle sagittal angle (PSA), and pedicle transverse angle (PTA).
  
  
  RESULTS
  Total numbers of 740 pedicles were measured in this present study. The mean OPW and IPW significantly increased from C3 to C7 while the mean OPH and IPH of those showed non-significant difference between any measured levels. The medial-lateral cortical thickness was significantly smaller than the superior-inferior one. PTA in the upper cervical spine was significantly wider than the lower ones. The PSA changed from upward inclination at upper cervical spine to the downward inclination at lower cervical spine.
  
  
  CONCLUSIONS
  This study has demonstrated that cervical vertebra has relatively small and narrow inner pedicle canal with thick outer pedicle cortex and also shows a variable in pedicle width and inconsistent transverse angle. To enhance the safety of CPS insertion, the entry point and trajectories should be determined individually by using preoperative MD-CT scan and the inner pedicle width should be a key parameter to determine the screw dimensions.
authors.forename: Pongsthorn
authors.initials: P
authors.lastname: Chanplakorn
authors.forename: Chaiwat
authors.initials: C
authors.lastname: Kraiwattanapong
authors.forename: Kitti
authors.initials: K
authors.lastname: Aroonjarattham
authors.forename: Pittavat
authors.initials: P
authors.lastname: Leelapattana
authors.forename: Gun
authors.initials: G
authors.lastname: Keorochana
authors.forename: Suphaneewan
authors.initials: S
authors.lastname: Jaovisidha
authors.affiliation: Department of Orthopedics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, 270 Rama VI Road, Phaya Thai, Ratchathewi, Bangkok 10400, Thailand. wiwat.waj@mahidol.ac.th.
authors.forename: Wiwat
authors.initials: W
authors.lastname: Wajanavisit
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D019637:Orthopedic Procedures / Q000295:instrumentation*; D011237:Predictive Value of Tests; D055815:Young Adult
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