title: Relationship Between Medial Meniscal Extrusion and Cartilage Loss in Specific Femorotibial Subregions: Data From the Osteoarthritis Initiative.
abstract: OBJECTIVE
  Medial meniscal extrusion is known to be related to structural progression of knee osteoarthritis. However, it is unclear whether medial meniscal extrusion is more strongly associated with cartilage loss in certain medial femorotibial subregions than in others.
  
  
  METHODS
  Segmentation of the medial tibial and femoral cartilage (baseline; 1-year followup) and the medial meniscus (baseline) was performed in 60 participants with frequent knee pain (mean ± SD ages 61.3 ± 9.2 years, body mass index 31.3 ± 3.9 kg/m(2) ) and with unilateral medial radiographic joint space narrowing (JSN) grades 1-3, using double-echo steady-state magnetic resonance images. Medial meniscal extrusion distance and extrusion area (percentage) between the external meniscal and tibial margin at baseline, and longitudinal medial cartilage loss in 8 anatomic subregions were determined.
  
  
  RESULTS
  A significant association (Pearson's correlation coefficient) was seen between medial meniscal extrusion area in JSN knees and cartilage loss over 1 year throughout the entire medial femorotibial compartment. The strongest correlation was with cartilage loss in the external medial tibia (r =-0.34, P < 0.01 in JSN; r =-0.30, P = 0.02 in knees without JSN).
  
  
  CONCLUSIONS
  Medial meniscal extrusion was associated with subsequent medial cartilage loss. The external medial tibial cartilage may be particularly vulnerable to thinning once the meniscus extrudes and its surface is exposed to direct, nonphysiological, cartilage-to-cartilage contact.
authors.affiliation: Paracelsus Medical University, Salzburg, and Krankenhaus der Barmherzigen Schwestern, Linz, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Bloecker
authors.affiliation: Paracelsus Medical University, Salzburg, Austria, and Chondrometrics, Ainring, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.affiliation: Boston University School of Medicine and Boston Imaging Core Lab, Boston, Massachusetts.
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.affiliation: Royal North Shore Hospital and Institute of Bone and Joint Research, Kolling Institute, and University of Sydney, Sydney, New South Wales, Australia.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.affiliation: Paracelsus Medical University, Salzburg, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Resch
authors.affiliation: Sisters of Charity Hospital, Linz, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Hochreiter
authors.affiliation: Paracelsus Medical University, Salzburg, Austria, and Chondrometrics, Ainring, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000453:epidemiology; D013977:Tibia / Q000473:pathology*