Trauma: Original ArticleDigital Radiographic Measurement of the Atlantodental Interval in ChildrenDouglas, Tania S. PhD*; Sanders, Virginia MSc*; Machers, Sven BSc*; Pitcher, Richard FCR†; van As, Arjan B. PhD‡ Author Information From the *MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town; †Department of Radiology, Red Cross War Memorial Children's Hospital, Cape Town; and ‡Department of Paediatric Surgery, Red Cross War Memorial Children's Hospital, Cape Town, South Africa. Support: Ms Sanders was employed by Lodox Systems, manufacturer of the StatScan system, at the time the study was carried out. None of the other authors received financial support for the study. Reprints: Tania S. Douglas, PhD, MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Observatory 7925, South Africa. E-mail: [email protected]. Journal of Pediatric Orthopaedics: January 2007 - Volume 27 - Issue 1 - p 23-26 doi: 10.1097/01.bpo.0000242443.42176.67 Buy Metrics Abstract The atlantodental interval (ADI) is assessed after trauma to the head and neck region to determine whether the transverse ligament of the atlas is intact. Atlantodental interval measurement from conventional screen-film radiographs is characterized by the need for magnification correction and by low reliability. Assessment of normal ADI values using digital radiography with computer-assisted measurement has not been reported. We compared with published values the digital radiographic measurements of ADI in children, examined the reliability of measurements, and examined the interaction between age, sex and ADI. Computer-assisted digital measurements of ADI in 101 children, aged 1 to 12 years, were obtained from lateral supine head-neutral radiographs. We found intraobserver reliability of 0.72 and 0.85, interobserver reliability of 0.50, a maximum ADI value of 3.5 mm, no effect of sex and age, and weak evidence for an interaction between sex and age. Computer-assisted digital ADI measurement provides higher intraobserver reliability than what has previously been reported, and interobserver reliability and a maximum ADI value similar to that found in the literature. © 2007 Lippincott Williams & Wilkins, Inc.