title: Evaluation of occipitocervical neutral position using lateral radiographs.
abstract: BACKGROUND
  Intraoperative assessment of neutral occipitocervical balance during a fusion procedure is challenging. We designed this study to introduce a more comprehensive method of evaluating the occipitocervical neutral position using lateral radiographs.
  
  
  METHODS
  One hundred neutral lateral cervical spine radiographs interpreted as normal were studied. Cervical spine radiographs were performed using a standard technique. The occipitocervical angle, the occipitocervical distance, and the mandible cervical distance were measured by different observers.
  
  
  RESULTS
  A difference analysis was performed between males and females. The mean mandible cervical distances were 11.0 and 11.2 mm in males and females, respectively. The mean occipitocervical distances were 22.0 mm (male) and 19.6 mm (female), and the occipitocervical angles were 47.2° (male) and 45.5° (female). The occipitocervical distance revealed significant differences between males and females (p <0.01). However, there were no significant differences between sexes for the occipitocervical angle or the mandible cervical distance (p >0.01).
  
  
  CONCLUSIONS
  This study offers reference values for the occipitocervical angle and occipitocervical distance for the estimation of the occipitocervical neutral position. The introduction of the mandible cervical distance may make the evaluation more direct and more comprehensive during surgery because of its sensitivity to changes in head position.
authors.forename: Jiangwei
authors.initials: J
authors.lastname: Tan
authors.affiliation: Department of Orthopedic Surgery, Yantaishan Hospital, No, 91 Jiefang Road, Zhifu district, Yantai 264000, People's Republic of China. guangjunl34@yeah.net.
authors.forename: Guangjun
authors.initials: G
authors.lastname: Liao
authors.forename: Shaoxian
authors.initials: S
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000293:injuries; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D004204:Joint Dislocations / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009777:Occipital Bone / Q000000981:diagnostic imaging; D011187:Posture; D011859:Radiography; D012016:Reference Values; D013123:Spinal Fusion / Q000379:methods*; D055815:Young Adult