title: Malformations of the atlas vertebra simulating the Jefferson fracture.
abstract: Congenital clefts and aplasias of the atlas vertebra, while rare, are often first encountered in the emergency room setting. Thirty-six patients with atlas malformations and 10 with Jefferson fractures were encountered. Sixteen of the patients with congenital malformations showed bilateral atlantoaxial lateral offset, a finding generally considered to be the result of fracture. The diagnosis of these abnormalities is readily made from plain films by noting their characteristic features. Anomalies produce lateral offset of 1-2 mm. Jefferson fractures produce a greater offset (over 3 mm).
mesh_terms: D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000293:injuries*; D001270:Cervical Atlas / Q000002:abnormalities* / Q000000981:diagnostic imaging; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D005596:Fractures, Closed / Q000000981:diagnostic imaging*; D006801:Humans; D011859:Radiography