title: Atlantoaxial interlaminar distances in cervical flexion in children.
abstract: OBJECTIVE
  To the best of the authors' knowledge, no quantitative analysis of the atlantoaxial interlaminar distance in flexion (ILD) in children exists in the medical literature. In this study they sought to determine the age-matched relationship between the posterior elements of the atlas and axis in children in cervical spine flexion, to be used as an adjunct to the atlantodental interval in common clinical use.
  
  
  METHODS
  Lateral radiographs of the cervical spine in full flexion were analyzed in 74 children. The atlantoaxial ILD was defined as the distance between a midpoint of the anterior cortices of the atlantal and axial posterior arches. The mean ILD for the entire group was 19 mm (range 8-30 mm). No significant difference was seen between male and female patients (p = 0.084). When stratified by age, the mean ILD was 12.3 +/- 3 mm (15 cases) in children age 3 years or younger and 20.5 +/- 4.7 mm (59 cases) in children age older than 3 years. Further stratification of the groups yielded a mean ILD of 10.4 +/- 1.4 [eight cases]) in children age 1 to 2 years, and 14.4 +/- 4.7 mm (seven cases) in children age 3 years. In children older than 3 years of age the mean ILD was consistently approximately 20 +/- 5 mm regardless of age.
  
  
  CONCLUSIONS
  Rapid, safe, and accurate diagnosis of the cervical spine is essential in critical care. Knowledge of the distance between the posterior elements of the atlas and axis in flexion should enhance the clinicians' (those who clear cervical spines) ability to diagnose accurately atlantoaxial instability on lateral radiographs obtained in flexion.
authors.affiliation: Department of Cell Biology, University of Alabama at Birmingham, Children's Hospital, Birmingham, Alabama 35233, USA. richard.tubbs@ccc.uab.edu
authors.forename: R Shane
authors.initials: RS
authors.lastname: Tubbs
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Smyth
authors.forename: John C
authors.initials: JC
authors.lastname: Wellons
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Blount
authors.forename: Paul A
authors.initials: PA
authors.lastname: Grabb
authors.forename: W Jerry
authors.initials: WJ
authors.lastname: Oakes
mesh_terms: D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D001268:Atlanto-Axial Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D012189:Retrospective Studies