Atlanto-occipital dissociation injuries

Changed by Ayush Goel, 21 Dec 2014

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Atlanto-occipital dissociation (AOD) injuries are severe and include both atlanto-occipital dislocations and atlanto-occipital subluxations.

Radiographic features

The key to the diagnosis, in addition to visualising gross disruption of the normal alignment of the atlanto-occipital joints is by using a number of lines on the lateral horizontal shoot-through cervical spine film ¹:

basion-dens interval (BDI) &gt~~; 12~~;12 mm in adults
basion-axial interval (BAI) &gt~~; 12~~;12 mm in adults
Powers ratio &gt~~; 1~~;1 (insensitive to a vertical distraction injury or posterior dissociation)
atlantodental interval (ADI) &gt~~; 3mm~~;3 mm in adult males, >2~~.5mm~~.5 mm in adult females

~~-<a href="/articles/basion-dens-interval">basion-dens interval (BDI)</a> > 12 mm in adults</li>~~
+<a href="/articles/basion-dens-interval">basion-dens interval (BDI)</a> >12 mm in adults</li>
~~-<a href="/articles/basion-axial-interval">basion-axial interval (BAI)</a> > 12 mm in adults</li>~~
+<a href="/articles/basion-axial-interval">basion-axial interval (BAI)</a> >12 mm in adults</li>
~~-<a href="/articles/powers-ratio">Powers ratio</a> > 1 (insensitive to a vertical distraction injury or posterior dissociation)</li>~~
+<a href="/articles/powers-ratio">Powers ratio</a> >1 (insensitive to a vertical distraction injury or posterior dissociation)</li>
~~-<a href="/articles/atlantodental-interval">atlantodental interval (ADI)</a> > 3mm in adult males, >2.5mm in adult females </li>~~
+<a href="/articles/atlantodental-interval">atlantodental interval (ADI)</a> >3 mm in adult males, >2.5 mm in adult females </li>

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Spine

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Atlanto-occipital dissociation injuries

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