title: Association between hip and knee cartilage measured using radiographs and magnetic resonance imaging: the Tasmanian Older Adult Cohort Study.
abstract: OBJECTIVE
  Cartilage loss is a key pathological feature of OA and can be assessed indirectly using radiography or directly through MRI. A number of cross-sectional studies have suggested that primary generalized osteoarthritis (PGOA) may be a distinct disease, but despite the high frequency of involvement of the hip and the knee joints in OA, very few studies have looked at the radiographic association between these two joints, and none has done so using MRI. The aim of this study was to examine the association of hip and knee cartilage measured by both radiography and MRI.
  
  
  METHODS
  We studied 151 participants from the Tasmanian Older Adult Cohort (TASOAC) study, who were selected randomly from the southern Tasmanian electoral rolls. MRI was used to assess hip and knee cartilage volume and radiography was used to assess joint space narrowing (JSN). Correlation analyses were used to compare cartilage volume measurements and JSN.
  
  
  RESULTS
  In adjusted analysis, there was a consistent, positive association between knee and hip cartilage volume that was best for total knee cartilage volume (r = 0.16-0.40, all P < 0.05). In contrast, there was at best a weak correlation, depending on the site, between hip and knee JSN (r = -0.01 to 0.21).
  
  
  CONCLUSIONS
  Hip and knee cartilage volume are more strongly associated than hip and knee JSN, suggesting a commonality of cartilage volume at different anatomic sites. The weaker radiographic association may reflect less measurement error with MRI or the contribution of multiple structures to joint space in the knee.
authors.affiliation: Musculoskeletal Unit, Menzies Research Institute, Medical Science 1 Building, Private Bag 23, 17-Liverpool Street, Hobart, Tasmania 7000, Australia. hussain.khan@utas.edu.au.
authors.forename: Hussain I
authors.initials: HI
authors.lastname: Khan
authors.forename: Dawn
authors.initials: D
authors.lastname: Aitken
authors.forename: Guangju
authors.initials: G
authors.lastname: Zhai
authors.forename: Changhai
authors.initials: C
authors.lastname: Ding
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Pelletier
authors.forename: Johanne Martel
authors.initials: JM
authors.lastname: Pelletier
authors.forename: Flavia
authors.initials: F
authors.lastname: Cicuttini
authors.forename: Leigh
authors.initials: L
authors.lastname: Blizzard
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000473:pathology*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography
keywords: MRI; X-ray; cartilage volume; hip; knee; osteoarthritis