Backward luxation of the atlas. Two cases of an uncommon condition.
D001172:Arthritis, Rheumatoid / Q000150:complications; D001368:Axis, Cervical Vertebra / Q000000981:diagnostic imaging; D001270:Cervical Atlas / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D014054:Tomography