title: Radiological assessment of the atlantoaxial distance in Down's syndrome.
abstract: People with Down's syndrome are pre-disposed to atlantoaxial instability. As part of a study to determine whether those with Down's syndrome should be screened for atlantoaxial instability before they participate in sport, a series of 279 children, aged 6 to 17 years was investigated radiologically. Lateral radiographs of the cervical spine were taken in neutral position and in flexion. The magnification factor was assessed by means of a marker attached to the nape of the neck. After correction for magnification 15% of the patients were found to have an atlantoaxial distance greater than 4 mm on the flexion film, especially boys under 11 years of age. However, sex and age together explained at most 9% of the variation in atlantoaxial distance. The maximum distance found was 6.5 mm. The disagreement between the means of first and second measurements by the same (test-retest) and by another (inter-) observer was more for those taken in the neutral position than in flexion. On a group level the results for reliability were satisfactory.
authors.affiliation: Janus Jongbloed Research Centre, University of Utrecht, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cremers
authors.forename: L
authors.initials: L
authors.lastname: Ramos
authors.forename: E
authors.initials: E
authors.lastname: Bol
authors.forename: J
authors.initials: J
authors.lastname: van Gijn
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000886:Anthropometry / Q000379:methods; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D002648:Child; D004314:Down Syndrome / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D008297:Male; D011859:Radiography; D015203:Reproducibility of Results; D012737:Sex Factors