title: Current prevalence and characteristics of cervical spine instability in patients with rheumatoid arthritis in the era of biologics.
abstract: OBJECTIVE
  Cervical spine instability (CSI) is commonly involved in patients with rheumatoid arthritis (RA). Although the treatment for RA has dramatically changed due to methotrexate and biologics, it is unclear whether this change contributes to the prevalence of CSI or not. Our objectives were to update the current prevalence of CSI and to investigate the factors associated with CSI.
  
  
  METHODS
  A cross-sectional study of patients with RA was conducted in our outpatient clinic. Clinical information and symptoms related to CSI were obtained. Plain radiography and magnetic resonance imaging were performed. CSI included atlantoaxial subluxation (AAS), vertical subluxation (VS), and subaxial subluxation (SAS).
  
  
  RESULTS
  Two hundred and twenty patients were analyzed, 93 (42%) of whom had CSI. A ≥ 10-year disease duration, Steinbrocker stage III, and three or more narrowed disc spaces from C2/3 to C6/7 were significantly associated with CSI. A neck pain VAS was associated with VS, but not with AAS and SAS. In contrast, methotrexate and biologics had no effect on CSI.
  
  
  CONCLUSIONS
  The prevalence of CSI in this study was lower compared to previous reports before the approval of biologic, although we failed to detect the effect of biologics. Further prospective studies are needed to elucidate the efficacy.
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Medical School , Osaka , Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Akinobu
authors.initials: A
authors.lastname: Suzuki
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Koike
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yasuda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tada
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sugioka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Okano
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging*; D001688:Biological Products / Q000627:therapeutic use*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011859:Radiography
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products
keywords: Cervical spine instability; Medication; Neck pain; Rheumatoid arthritis