title: Classification of odontoid destruction in patients with rheumatoid arthritis using reconstructed computed tomography: reference to vertical migration.
abstract: OBJECTIVE
  To reveal the factors that determine the natural course of subluxation of occipital-cervical lesions in rheumatoid arthritis (RA). The atlanto-axial region is one of the most common locations for lesions in RA. Some cases progress from reducible atlanto-axial subluxation (AAS) to irreducible vertical migration, while others continue to exhibit reducible AAS. No study has revealed the factors that determine the natural course of subluxation. We focus on the odontoid as a key structure of the progression of occipito-cervical lesions and investigated this region in patients with RA using reconstructive computed tomography (CT) images, and analyzed factors in association with CT findings.
  
  
  METHODS
  Fifty-eight patients with RA and 40 age-matched controls, all women, were studied. Associated factors, including C-reactive protein, erythrocyte sedimentation rate, steroid usage, and the severity of local osteoporosis, were analyzed as measurements in association with odontoid destruction.
  
  
  RESULTS
  The destruction of odontoid and atlanto-odontoid joint were common in patients with RA. The more destruction observed in the odontoid process, the greater is the degree of progression of vertical migration. Local osteoporosis is a significant factor in odontoid destruction, based on a cortico-cancellous index of 42% in cases of grade III odontoid destruction.
  
  
  CONCLUSIONS
  The odontoid process is a key structure in the progression of occipito-cervical lesions in patients with RA.
authors.affiliation: Orthopaedic Surgery, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shimada
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abematsu
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishido
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawamura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tominaga
authors.forename: Michihisa
authors.initials: M
authors.lastname: Zenmyo
authors.forename: Takuya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Taketomi
authors.forename: Setsuro
authors.initials: S
authors.lastname: Komiya
authors.forename: Kosei
authors.initials: K
authors.lastname: Ijiri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000473:pathology; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000473:pathology*; D008875:Middle Aged; D009809:Odontoid Process / Q000000981:diagnostic imaging* / Q000473:pathology; D011446:Prospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed