title: Computed tomographic evaluation of odontoid process: implications for anterior screw fixation of odontoid fractures in an adult population.
abstract: BACKGROUND
  Odontoid diameter in some individuals may not be large enough to accommodate two 3.5-mm cortical screws for anterior odontoid fracture fixation. The study was performed to evaluate, in a Brazilian population, the diameter of the odontoid process and the feasibility of using two 3.5-mm cortical screws for anterior odontoid fracture fixation.
  
  
  METHODS
  Computed tomographic (CT) scans of 88 adult patients (aged 18-78 years) were analyzed; 40 patients (45%) were male (mean age: 43.08 years) and 48 (55%) were female (mean age: 43.39 years). The minimum external and internal anteroposterior and transverse diameters of the odontoid process on sagittal and coronal planes were measured on CT multiplanar reconstructions of the cervical spine.
  
  
  RESULTS
  The mean value of the minimum external anteroposterior diameter was 10.83 ± 1.08 and 7.53 ± 1.10 mm for the minimum internal anteroposterior diameter. The mean value of the minimum external transverse diameter was 9.19 ± 0.91 and 6.07 ± 1.08 mm for the minimum internal transverse diameter. The mean AP diameter was significantly larger than the mean transverse diameter; 57 (65%) individuals had the minimum external transverse diameter >9.0 mm that would allow the insertion of two 3.5-mm cortical screws with tapping, and five (6%) individuals had the minimum internal transverse diameter >8.0 mm that would allow the insertion of two 3.5-mm cortical screws without tapping.
  
  
  CONCLUSIONS
  The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fracture in 57 (65%) individuals of our study, and there was no statistical difference between males and females.
authors.affiliation: Spine Division, Department of Orthopaedics and Traumatology, Federal University of Goiás, Rua 109 nº 331 aptº 301 Setor Sul, Goiânia-Go, CEP 74085-090, Brazil. murilodaher@uol.com.br
authors.forename: Murilo Tavares
authors.initials: MT
authors.lastname: Daher
authors.forename: Sérgio
authors.initials: S
authors.lastname: Daher
authors.forename: Marcello Henrique
authors.initials: MH
authors.lastname: Nogueira-Barbosa
authors.forename: Helton Luíz Aparecido
authors.initials: HL
authors.lastname: Defino
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001863:Bone Screws; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000000981:diagnostic imaging* / Q000293:injuries / Q000601:surgery; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed