title: Normal Development and Measurements of the Occipital Condyle-C1 Interval in Children and Young Adults.
abstract: Widening of the occipital condyle-C1 interval is the most specific and sensitive means of detecting atlanto-occipital dislocation. Recent studies attempting to define normal measurements of the condyle-C1 interval in children have varied substantially. This study was performed to test the null hypothesis that condyle-C1 interval morphology and joint measurements do not change as a function of age.
  
  
  
  Imaging review of subjects undergoing CT of the upper cervical spine for reasons unrelated to trauma or developmental abnormality was performed. Four equidistant measurements were obtained for each bilateral condyle-C1 interval on sagittal and coronal images. The cohort was divided into 7 age groups to calculate the mean, SD, and 95% CIs for the average condyle-C1 interval in both planes. The prevalence of a medial occipital condyle notch was calculated.
  
  
  
  Two hundred forty-eight joints were measured in 124 subjects with an age range of 2 days to 22 years. The condyle-C1 interval varies substantially by age. Average coronal measurements are larger and more variable than sagittal measurements. The medial occipital condyle notch is most prevalent from 1 to 12 years and is uncommon in older adolescents and young adults.
  
  
  
  The condyle-C1 interval increases during the first several years of life, is largest in the 2- to 4-year age range, and then decreases through late childhood and adolescence. A single threshold value to detect atlanto-occipital dissociation may not be sensitive and specific for all age groups. Application of this normative data to documented cases of atlanto-occipital injury is needed to determine clinical utility.
authors.affiliation: From the Departments of Radiology (P.S., L.L.L., J.L.L.).
authors.forename: P
authors.identifier: 0000-0002-3573-5731
authors.initials: P
authors.lastname: Smith
authors.affiliation: From the Departments of Radiology (P.S., L.L.L., J.L.L.) luke.linscott@cchmc.org.
authors.forename: L L
authors.identifier: 0000-0001-6074-0789
authors.initials: LL
authors.lastname: Linscott
authors.affiliation: Neurosurgery (S.V.).
authors.forename: S
authors.identifier: 0000-0003-1419-5673
authors.initials: S
authors.lastname: Vadivelu
authors.affiliation: Epidemiology and Biostatistics (B.Z.), Cincinnati Children's Hospital Medical Center, University of Cincinnati Medical School, Cincinnati, Ohio.
authors.forename: B
authors.identifier: 0000-0003-0607-1806
authors.initials: B
authors.lastname: Zhang
authors.affiliation: From the Departments of Radiology (P.S., L.L.L., J.L.L.).
authors.forename: J L
authors.identifier: 0000-0002-6574-9982
authors.initials: JL
authors.lastname: Leach
mesh_terms: D000293:Adolescent; D001269:Atlanto-Occipital 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; D007231:Infant, Newborn; D008297:Male; D009777:Occipital Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012016:Reference Values; D014057:Tomography, X-Ray Computed; D055815:Young Adult