title: Contribution of regional 3D meniscus and cartilage morphometry by MRI to joint space width in fixed flexion knee radiography--a between-knee comparison in subjects with unilateral joint space narrowing.
abstract: BACKGROUND
  Radiographic joint space width (JSW) is considered the reference standard for demonstrating structural therapeutic benefits in knee osteoarthritis. Our objective was to determine the proportion by which 3D (regional) meniscus and cartilage measures explain between-knee differences of JSW in the fixed flexion radiographs.
  
  
  METHODS
  Segmentation of the medial meniscus and tibial and femoral cartilage was performed in double echo steady state (DESS) images. Quantitative measures of meniscus size and position, femorotibial cartilage thickness, and radiographic JSW (minimum, and fixed locations) were compared between both knees of 60 participants of the Osteoarthritis Initiative, with strictly unilateral medial joint space narrowing (JSN). Statistical analyses (between-knee, within-person comparison) were performed using regression analysis.
  
  
  RESULTS
  A strong relationship with side-differences in minimum and a central fixed location JSW was observed for percent tibial plateau coverage by the meniscus (r = .59 and .47; p<.01) and central femoral cartilage thickness (r = .69 and .75; p<.01); other meniscus and cartilage measures displayed lower coefficients. The correlation of central femoral cartilage thickness with JSW (but not that of meniscus measures) was greater (r = .78 and .85; p<.01) when excluding knees with non-optimal alignment between the tibia and X-ray beam.
  
  
  CONCLUSIONS
  3D measures of meniscus and cartilage provide significant, independent information in explaining side-differences in radiographic JSW in fixed flexion radiographs. Tibial coverage by the meniscus and central femoral cartilage explained two thirds of the variability in minimum and fixed location JSW. JSW provides a better representation of (central) femorotibial cartilage thickness, when optimal positioning of the fixed flexion radiographs is achieved.
authors.affiliation: Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria; Department of Traumatology and Sports Medicine, Paracelsus Medical University, Müllner Hauptstrasse 48, 5020 Salzburg, Austria. Electronic address: katja.bloecker@pmu.ac.at.
authors.forename: K
authors.initials: K
authors.lastname: Bloecker
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: J
authors.initials: J
authors.lastname: Duryea
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.forename: C K
authors.initials: CK
authors.lastname: Kwoh
authors.forename: H
authors.initials: H
authors.lastname: Resch
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
mesh_terms: D000368:Aged; D001175:Arthrography / Q000379:methods*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis*; D056888:Patient Positioning / Q000379:methods*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: 3D MRI quantitative imaging; Cartilage morphometry; Fixed flexion knee radiography; Joint space width; Meniscus morphometry