title: Synovitis and the risk of knee osteoarthritis: the MOST Study.
abstract: OBJECTIVE
  To identify the independent relation of synovitis with incident radiographic knee osteoarthritis (OA) after adjusting for other structural factors known to cause synovitis.
  
  
  METHODS
  We examined MRIs from knees that developed incident radiographic OA from the Multicenter Osteoarthritis Study (MOST) and compared these case knees with controls that did not develop OA. We examined baseline MRIs for knees developing OA at any time up to 84 months follow-up. We scored lesions in cartilage, meniscus, bone marrow and synovitis. Synovitis scores were summed (0-9) across three regions, suprapatellar, infrapatellar and intercondylar region, each of which was scored 0-3. After bivariate analyses examining each factor's association with incidence, we carried out multivariable regression analyses adjusting for age, sex, BMI, alignment and cartilage and meniscal damage.
  
  
  RESULTS
  We studied 239 case and 731 control knees. In bivariate analyses, cartilage lesions, meniscal damage, synovitis and bone marrow lesions were all risk factors for OA. After multivariable analyses, synovitis was associated with incident OA. A higher synovitis score increased the risk of incident OA (adjusted OR per unit increase 1.1; (95% CI 1.0, 1.2, P = .02)), but increased risk was associated only with synovitis scores of ≥3 (adjusted OR 1.6; 95% CI 1.2, 2.1, P = .003).
  
  
  CONCLUSIONS
  Synovitis, especially when there is a substantial volume within the knee, is an independent cause of OA.
authors.affiliation: Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, Boston, MA, USA; Arthritis Research UK Epidemiology Unit, University of Manchester, Manchester, UK; NIHR Biomedical Research Unit, University of Manchester, Manchester, UK. Electronic address: dfelson@bu.edu.
authors.forename: D T
authors.initials: DT
authors.lastname: Felson
authors.affiliation: Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Niu
authors.affiliation: Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Neogi
authors.affiliation: Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Goggins
authors.affiliation: Division of Clinical Trials & Multicenter Studies, University of California at San Francisco, San Francisco, CA, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Nevitt
authors.affiliation: Quantitative Imaging Center, Boston University School of Medicine, Boston, MA, USA.
authors.forename: F
authors.initials: F
authors.lastname: Roemer
authors.affiliation: Department of Epidemiology, The University of Iowa, Iowa City, IA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Torner
authors.affiliation: Division of Preventive Medicine, University of Alabama School of Medicine, Birmingham, AL, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Lewis
authors.affiliation: Quantitative Imaging Center, Boston University School of Medicine, Boston, MA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
mesh_terms: D000368:Aged; D000407:Alabama / Q000453:epidemiology; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D013583:Synovial Membrane / Q000473:pathology; D013585:Synovitis / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D000070600:Tibial Meniscus Injuries / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology
keywords: Cohort studies; Incidence; Knee osteoarthritis; Magnetic resonance imaging