Atlantodental interval

Dr Craig Hacking et al.

The atlantodental interval (ADI), as the name suggests, is the horizontal distance between the anterior arch of the atlas and the dens of the axis, used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis.

It is the distance (in mm) between the posterior cortex of the anterior arch of the atlas and the anterior cortex of the dens in the median (midsagittal) plane.

Normal values are:

  • <2 mm on plain radiographs 1 although most authors describe <3 mm
  • <3 mm in males and <2.5 mm in females on CT 1
  • <5 mm in children
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Article information

rID: 40483
Section: Gamuts
Synonyms or Alternate Spellings:
  • ADI
  • Atlantodental interval (ADI)
  • Atlanto-dental interval (ADI)

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