title: Natural history of cartilage damage and osteoarthritis progression on magnetic resonance imaging in a population-based cohort with knee pain.
abstract: OBJECTIVE
  To determine the natural history of cartilage damage and of osteoarthritis (OA) progression using magnetic resonance imaging (MRI); to evaluate whether OA progression varies by stage of disease.
  
  
  METHODS
  A population-based cohort with knee pain was assessed clinically, with X-ray (Kellgren-Lawrence [KL] grading) and MRI. Cartilage was graded 0-3 on six joint surfaces. Frequency of cartilage damage change was determined for each joint site. Progression of OA was defined as a worsening of MRI cartilage damage by ≥1 grade in at least two joint sites or ≥2 grades in at least one joint site. The association of KL grade with OA progression was evaluated using parametric lifetime regression analysis.
  
  
  RESULTS
  163 subjects were assessed at baseline and follow-up (mean 3.2 years). KL grade ≥2 was present in 39.4% at baseline. An increase in cartilage damage by ≥1 grade was seen in 8.0-14.1% of subjects at different joint sites. OA progression on MRI was present in 15.5%. Baseline KL grade was a significant predictor of OA progression with hazard ratio (HR) of 6.5 (95% confidence interval [CI] 1.4-30.7), 6.1 (95% CI 1.3-28.9), and 9.2 (95% CI 1.9-44.9) for KL grades 1, 2 and ≥3, respectively.
  
  
  CONCLUSIONS
  A low OA progression rate was seen over 3 years in this population-based symptomatic cohort. Radiographic severity, including KL grade 1, was a significant predictor of OA progression. Future interventions aimed at reducing progression will need to target not only radiographic OA, but also those with early abnormalities suggestive of pre-radiographic OA.
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, BC, Canada; Arthritis Research Centre of Canada, Vancouver, BC, Canada. jcibere@arthritisresearch.ca
authors.forename: J
authors.initials: J
authors.lastname: Cibere
authors.forename: E C
authors.initials: EC
authors.lastname: Sayre
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.forename: S
authors.initials: S
authors.lastname: Nicolaou
authors.forename: J A
authors.initials: JA
authors.lastname: Kopec
authors.forename: J M
authors.initials: JM
authors.lastname: Esdaile
authors.forename: A
authors.initials: A
authors.lastname: Thorne
authors.forename: J
authors.initials: J
authors.lastname: Singer
authors.forename: H
authors.initials: H
authors.lastname: Wong
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D011859:Radiography