The occurrence of atlantoaxial rotatory subluxation is fairly uncommon; however, it is
more common to be encountered in the paediatric population, typically seen after a
retropharyngeal inflammation or after a minor trauma. Ligamentous laxity, shallower
and more horizontally oriented facet joints especially at the C1-2 joint making them
prone to have atlantoaxial subluxation or dislocation. (Copied from article).