title: Acquired os odontoideum. A case report.
abstract: A 7-year-old boy presented with os odontoideum after a 5 story fall at 19 months of age, at which time roentgenograms documented a normal odontoid. Current flexion-extension films revealed a marked altlantoaxial instability related to the acquired "os." The treatment consisted of an atlantoaxial arthrodesis. Acquired os odontoideum is a recognized, though uncommon entity in which it is hypothesized that trauma produces vascular insufficiency, with subsequent resorption of the central portion of the odontoid, resulting in the classical features of os odontoideum. It is often associated with instability, with potential danger to the spinal cord. Instability in cases of os odontoideum is a positive indication for atlantoaxial arthrodesis.
mesh_terms: D001368:Axis, Cervical Vertebra / Q000601:surgery; D001270:Cervical Atlas / Q000601:surgery; D002648:Child; D006801:Humans; D008297:Male; D013122:Spinal Diseases / Q000209:etiology / Q000601:surgery; D013123:Spinal Fusion; D013124:Spinal Injuries / Q000150:complications*