title: Magnetic resonance analysis of loaded meniscus deformation: a novel technique comparing participants with and without radiographic knee osteoarthritis.
abstract: OBJECTIVE
  To establish a novel method of quantifying meniscal deformation using loaded MRI. More specifically, the goals were to evaluate the (1) accuracy, (2) inter-rater reliability, (3) intra-rater reliability, and (4) scan-rescan reliability. The secondary purpose of this experiment was to evaluate group differences in meniscal deformation in participants with and without radiographic knee OA.
  
  
  METHODS
  Weight-bearing 3-T MRIs of the knee in full extension and 30° of flexion were processed to create 3D models of meniscal deformation. Accuracy was assessed using a custom-designed phantom. Twenty-one participants either with or without signs of OA were evaluated, and another six participants (14 knees, one subject was scanned twice) underwent repeated imaging to assess scan-rescan reproducibility. Intraclass correlation coefficient (ICC), root-mean squared error (RMSE), and root-mean-square percent coefficient-of-variation (RMS%CV) analyses were performed. Exploratory comparisons were made between those with and without OA to evaluate potential group differences.
  
  
  RESULTS
  All variables were found to be accurate with RMSE ranging from 0.08 to 0.35 mm and 5.99 to 14.63 mm(2). Reproducibility of peak anterior-posterior meniscal deformation was excellent (ICC > 0.821; p < 0.013) with RMS%CV for intra-rater ranging from 0.06 to 1.53 % and 0.17 to 1.97 %, inter-rater ranging from 0.10 to 7.20 % and 3.95 to 18.53 %, and scan-rescan reliability ranging from 1.531 to 7.890 % and 4.894 to 9.142 %, for distance and area metric, respectively. Participants with OA were found to have significantly greater anterior horn movement of both the medial (p = 0.039) and lateral meniscus (p = 0.015), and smaller flexed medial meniscus outer area (p = 0.048) when compared to controls.
  
  
  CONCLUSIONS
  MRI-based variables of meniscus deformation were found to be valid in participants with and without OA. Significant differences were found between those with and without radiographic OA; further study is warranted.
authors.affiliation: Department of Physical Therapy, California State University, 6000 J Street, Sacramento, CA, 95819-6020, USA, toran.macleod@csus.edu.
authors.forename: Toran D
authors.initials: TD
authors.lastname: MacLeod
authors.forename: Karupppasamy
authors.initials: K
authors.lastname: Subburaj
authors.forename: Samuel
authors.initials: S
authors.lastname: Wu
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.forename: Cory
authors.initials: C
authors.lastname: Wyatt
authors.forename: Richard B
authors.initials: RB
authors.lastname: Souza
mesh_terms: D001175:Arthrography / Q000379:methods*; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D008875:Middle Aged; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016474:Weight-Bearing