title: Lateralized Odontoid in Plain Film Radiography: Sign of Fractures? A Comparison Study with MDCT.
abstract: OBJECTIVE
  To evaluate X-ray standards for the detection of odontoid fractures.
  
  
  BACKGROUND
  Cervical spine fractures are a common finding in emergency medicine, accounting for 1-3% of injuries. Involvement of the C1/C2 complex is found in 25% of cases, affecting the odontoid peg in 55-80%. Regarding the consequences of missed fractures, radiographic techniques built the groundwork for further treatment procedures. As standardized X-ray measurements have not been established, the incidence of unrecognized cervical spine fracture is expected to be up to 20%. The establishment of X-ray-based guidelines is also limited by the presumed low specificity and sensitivity of distance measurements caused by rotational distortion which leads to a rising popularity of CT.
  
  
  METHODS
  79 (age 60 ± 26 yrs) patients with lateralization of the odontoid process on conventional plain film radiography (anteroposterior, lateral, and open mouth odontoid process view projection) were examined. The distance between the odontoid process and lateral mass of C1, angles of vertical odontoid line and basis of C2 were measured in the ap view. In the lateral view, dorsal alignment and atlantodental distance were assessed. MDCT examinations were used as a reference. Discriminatory power test was applied to assess significance.
  
  
  RESULTS
  8/79 (10.1%) odontoid process fractures were found. Diagnosis was achieved on conventional radiographs in 6 patients. Neither distance and angle measurements between odontoid and C1 nor the dorsal alignment of the vertebral bodies differed significantly between healthy and affected patients.
  
  
  CONCLUSIONS
  Decentralization of the odontoid process is not necessarily an indirect sign for its fracture. In patients with suspected injury of the odontoid process, an MDCT scan might be the method of choice to rule out a fracture.
  
  
  CONCLUSIONS
  Due to the wide physiological variety of odontoid process position, even a detailed metric analysis of cervical alignment and odontoid process angulation in X-ray scans is not able to facilitate the diagnosis of odontoid process fractures. In the case of cervical spine trauma, which necessitate medical imaging, a primary MDCT scan should be the method of choice.
authors.forename: S
authors.initials: S
authors.lastname: Keller
authors.forename: K
authors.initials: K
authors.lastname: Bieck
authors.forename: M
authors.initials: M
authors.lastname: Karul
authors.forename: B
authors.initials: B
authors.lastname: Schönnagel
authors.forename: G
authors.initials: G
authors.lastname: Adam
authors.forename: C
authors.initials: C
authors.lastname: Habermann
authors.forename: J
authors.initials: J
authors.lastname: Yamamura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005188:False Negative Reactions; D006801:Humans; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D009809:Odontoid Process / Q000000981:diagnostic imaging*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016103:Spinal Fractures / Q000000981:diagnostic imaging*; D014962:X-Ray Film; D055815:Young Adult