title: Magnetic resonance imaging-based cartilage loss in painful contralateral knees with and without radiographic joint space narrowing: Data from the Osteoarthritis Initiative.
abstract: OBJECTIVE
  To determine by magnetic resonance imaging (MRI), whether knees with advanced radiographic disease (medial joint space narrowing [mJSN]) encounter greater longitudinal cartilage loss than contralateral knees with earlier disease (no or less mJSN).
  
  
  METHODS
  Participants were selected from 2,678 cases in the Osteoarthritis Initiative, based on exhibition of bilateral pain, body mass index >25 (kg/m(2)), mJSN in 1 knee, no or less mJSN in the contralateral knee, and no lateral JSN in both knees. Eighty participants (mean +/- SD age 60.6 +/- 9.1 years) fulfilled these criteria. Medial tibial and femoral cartilage morphology was analyzed from the baseline and the 1-year followup MRI (sagittal double echo at steady state by 3.0T) of both knees by experienced readers blinded to the time point and mJSN status.
  
  
  RESULTS
  Knees with more radiographic mJSN displayed greater medial cartilage loss (-80 mum) assessed by MRI than contralateral knees with less mJSN (-57 mum). The difference reached statistical significance in participants with an mJSN grade of 2 or 3 (P = 0.005-0.08), but not in participants with an mJSN grade of 1 (P = 0.28-0.98). In knees with more mJSN, cartilage loss increased with higher grades of mJSN (P = 0.003 in the medial femur). Knees with an mJSN grade of 2 or 3 displayed greater cartilage loss in the weight-bearing medial femur than in the posterior femur or in the medial tibia (P = 0.048).
  
  
  CONCLUSIONS
  Knees with advanced mJSN displayed greater cartilage loss than contralateral knees with less mJSN. These data suggest that radiography can be used to stratify fast structural progressors, and that MRI cartilage thickness loss is more pronounced at advanced radiographic disease stage.
authors.affiliation: Paracelsus Medical University, Salzburg, Austria, and Chondrometrics, Ainring, Germany. felix.eckstein@pmu.ac.at
authors.forename: Felix
authors.initials: F
authors.lastname: Eckstein
authors.forename: Olivier
authors.initials: O
authors.lastname: Benichou
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wirth
authors.forename: David R
authors.initials: DR
authors.lastname: Nelson
authors.forename: Susanne
authors.initials: S
authors.lastname: Maschek
authors.forename: Martin
authors.initials: M
authors.lastname: Hudelmaier
authors.forename: C Kent
authors.initials: CK
authors.lastname: Kwoh
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
authors.forename: David
authors.initials: D
authors.lastname: Hunter
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000000981:diagnostic imaging / Q000473:pathology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology*; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology