title: Pathogenetic mechanism and prevalence of the stable atlantoaxial subluxation in rheumatoid arthritis.
abstract: OBJECTIVE
  To study the pathogenetic mechanisms responsible for and prevalence of stable atlantoaxial subluxation (AAS).
  
  
  METHODS
  Lateral view cervical spine radiographs during flexion and extension were studied in 262 patients with rheumatoid arthritis (RA).
  
  
  RESULTS
  AAS was found in 130 patients, 42 (32%) of whom had a stable deformity; in a population based subseries, stable AAS was seen in 16% of the patients with ASS. Atlantoaxial impaction (AAI) was diagnosed in 98 cases and in 37 (88%) of the 42 patients with stable AAS.
  
  
  CONCLUSIONS
  The main cause of the spontaneous stabilization and occasional ankylosis of the atlantoaxial area is the development of erosions and collapse in the lateral facet joints leading to AAI.
authors.affiliation: Rheumatism Foundation Hospital, Heinola, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Kauppi
authors.forename: M
authors.initials: M
authors.lastname: Sakaguchi
authors.forename: Y T
authors.initials: YT
authors.lastname: Konttinen
authors.lastname: HämäläinenM
authors.forename: M
authors.initials: M
authors.lastname: Hakala
mesh_terms: D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000473:pathology; D001268:Atlanto-Axial Joint; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D015995:Prevalence; D011859:Radiography