title: Lateral and medial joint space narrowing predict subsequent cartilage loss in the narrowed, but not in the non-narrowed femorotibial compartment--data from the Osteoarthritis Initiative.
abstract: OBJECTIVE
  To determine the predictive value of unicompartimental joint space narrowing (JSN) for MRI-based cartilage thickness loss in the narrowed and the non-narrowed femorotibial compartment.
  
  
  METHODS
  922 knees from 922 Osteoarthritis Initiative (OAI) participants (62.2 ± 9.0 years, 61% females) with radiographic OA (158 without JSN [noJSN], 175 with lateral JSN [latJSN], 589 with medial JSN [medJSN]) were analyzed using 3 T MRI. One-year cartilage thickness change was determined in the lateral (LFTC) and medial femorotibial compartment (MFTC), and in femorotibial subregions. The probability of subsequent cartilage loss was calculated using predefined thresholds. The predictive value of JSN for the probability and magnitude of cartilage loss was compared between latJSN, medJSN and noJSN knees using Fisher's exact and Mann-Whitney-U tests.
  
  
  RESULTS
  The probability of cartilage loss was greater in the narrowed compartment of latJSN/medJSN knees (34.9%/32.4%) than in noJSN knees (13.3%/12.7%, P ≤ 6.4 × 10(-6)) and so was the magnitude of cartilage thickness change (P ≤ 8.2 × 10(-6)). No significant differences were observed between the narrowed compartments of latJSN vs. medJSN knees (probability: P = 0.58, magnitude: P = 0.19) or between the non-narrowed compartment of latJSN/medJSN vs. noJSN knees (probability: P ≥ 0.35, magnitude: P = ≥0.23). These results were confirmed by the location-independent ordered value (OV) analyses of femorotibial subregions.
  
  
  CONCLUSIONS
  The predictive value of latJSN for lateral compartment cartilage loss was comparable to that of medJSN for medial compartment cartilage loss, whereas cartilage loss in the non-narrowed compartment was similar to that in noJSN knees. These findings provide important clues to predicting progression of knee OA, and in tailoring inclusion criteria for clinical trials.
authors.affiliation: Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg, Austria; Chondrometrics GmbH, Ainring, Germany. Electronic address: wolfgang.wirth@pmu.ac.at.
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.affiliation: University of California San Francisco, San Francisco, CA, USA. Electronic address: mnevitt@psg.ucsf.edu.
authors.forename: M
authors.initials: M
authors.lastname: Nevitt
authors.affiliation: Pfizer Global Research and Development, New London, CT, USA. Electronic address: helliomp@pfizer.com.
authors.forename: M-P
authors.initials: MP
authors.lastname: Hellio Le Graverand
authors.affiliation: University of California San Francisco, San Francisco, CA, USA. Electronic address: JLynch@psg.ucsf.edu.
authors.forename: J
authors.initials: J
authors.lastname: Lynch
authors.affiliation: Chondrometrics GmbH, Ainring, Germany. Electronic address: dr-susannemaschek@web.de.
authors.forename: S
authors.initials: S
authors.lastname: Maschek
authors.affiliation: Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg, Austria; Chondrometrics GmbH, Ainring, Germany. Electronic address: martin.hudelmaier@pmu.ac.at.
authors.forename: M
authors.initials: M
authors.lastname: Hudelmaier
authors.affiliation: Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg, Austria; Chondrometrics GmbH, Ainring, Germany. Electronic address: felix.eckstein@pmu.ac.at.
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D013977:Tibia / Q000473:pathology
keywords: Cartilage loss; Knee osteoarthritis; Lateral joint space narrowing; Magnetic resonance imaging; cartilage thickness