title: Comparison of conventional standing knee radiographs and magnetic resonance imaging in assessing progression of tibiofemoral joint osteoarthritis.
abstract: OBJECTIVE
  Although the current recommendation is to measure radiographic joint space width (JSW) to assess structural change in osteoarthritis (OA), there is increasing interest in direct measurement of cartilage volume from magnetic resonance imaging (MRI). We performed a longitudinal study to compare change in both JSW and articular cartilage volume in subjects with symptomatic knee OA.
  
  
  METHODS
  JSW was measured in 28 subjects with knee OA (57% females, mean age 62.8+/-9.8 years) who had standing radiographs in full extension, where both radiographs had satisfactory alignment. Each subject had femoral, tibial and combined femoral and tibial cartilage volumes determined from T1-weighted fat saturated sagittal knee MRI. All subjects had a repeat of the knee radiograph and MRI 1.96+/-0.4 years later.
  
  
  RESULTS
  At baseline there was a moderate, but statistically significant, correlation between JSW and femoral and tibial cartilage volumes in the medial tibiofemoral joint, which was strengthened by adjusting for medial tibial bone size (R=0.58-0.66, P=0.001). Although we observed a reduction in JSW and femoral and tibial cartilage volumes over the study period, there was no significant association between reduction in JSW and cartilage volume (R<0.13). There was a trend towards a significant association between change in medial tibiofemoral cartilage volume and joint replacement at 4 years (OR=9.0, P=0.07) but not change in medial tibiofemoral JSW (OR=1.1, P=0.92).
  
  
  CONCLUSIONS
  Although there was a modest correlation between cartilage volume and JSW in the medial tibiofemoral compartment, there was no correlation between longitudinal change in these measures. Change in cartilage volume appears to be a better predictor of joint replacement. Further work in larger samples over a longer period of time will be needed to confirm these findings.
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University Medical School, Alfred Hospital, Prahran, Victoria 3181, Australia. flavia.cicuttini@med.monash.edu
authors.forename: F
authors.initials: F
authors.lastname: Cicuttini
authors.forename: J
authors.initials: J
authors.lastname: Hankin
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.forename: A
authors.initials: A
authors.lastname: Wluka
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005269:Femur; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D010147:Pain Measurement; D011859:Radiography; D013977:Tibia; D016896:Treatment Outcome