title: Trabecular bone structure and spatial differences in articular cartilage MR relaxation times in individuals with posterior horn medial meniscal tears.
abstract: OBJECTIVE
  To analyze knee trabecular bone structure and spatial cartilage T(1ρ) and T(2) relaxation times using 3-T magnetic resonance imaging (MRI) in subjects with and without tears of posterior horn of the medial meniscus (PHMM).
  
  
  METHODS
  3-T MRI from 59 subjects (>18 years), were used to evaluate PHMM tears based on modified Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring; and to calculate apparent trabecular bone-volume over total bone volume fraction (app. BV/TV), apparent trabecular number (app. Tb.N), apparent trabecular separation (app. Tb.Sp) and apparent trabecular thickness (app. Tb.Th) for overall femur/tibia and medial/lateral femur/tibia; and relaxation times for deep and superficial layers of articular cartilage. A repeated measures analysis using Generalized Estimating Equation (GEE) was performed to compare trabecular bone and cartilage relaxation time parameters between people with (n = 35) and without (n = 24) PHMM tears, while adjusting for age and knee OA presence.
  
  
  RESULTS
  Subjects with PHMM tears had lower app. BV/TV and app. Tb.N, and greater app. Tb.Th, and app. Tb.Sp. They also had higher T(1ρ) times in the deep cartilage layer for lateral tibia and medial femur and higher T(2) relaxation times for the deep cartilage layer across all compartments.
  
  
  CONCLUSIONS
  PHMM tears are associated with differences in underlying trabecular bone and deep layer of cartilage. Over-load of subchondral bone can lead to its sclerosis and stress shielding of trabecular bone leading to the resorptive changes observed in this study. The results underline the importance of interactions of trabecular bone and cartilage in the pathogenesis of knee OA in people with PHMM tears.
authors.affiliation: Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA. deepak.kumar@ucsf.edu
authors.forename: D
authors.initials: D
authors.lastname: Kumar
authors.forename: J
authors.initials: J
authors.lastname: Schooler
authors.forename: J
authors.initials: J
authors.lastname: Zuo
authors.forename: C E
authors.initials: CE
authors.lastname: McCulloch
authors.forename: L
authors.initials: L
authors.lastname: Nardo
authors.forename: T M
authors.initials: TM
authors.lastname: Link
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: S
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D002357:Cartilage Diseases / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D013977:Tibia / Q000473:pathology