title: Characteristics of displaceable and nondisplaceable meniscal tears at kinematic MR imaging of the knee.
abstract: OBJECTIVE
  To prospectively determine if kinematic magnetic resonance (MR) imaging of the knee may demonstrate displacement of menisci with tears and, if so, to characterize displaceable and nondisplaceable meniscal tears.
  
  
  METHODS
  The study was approved by the hospital's review board, and informed consent was obtained. Forty-two patients (30 men, 12 women; mean age, 36.9 years) with 43 arthroscopically documented meniscal tears visible at 1.5-T MR imaging underwent kinematic MR imaging with an open-configuration 0.5-T MR imager with their knees in supine neutral, supine with 90 degrees flexion and external or internal rotation, and upright weight-bearing positions. Analysis of meniscal movement was performed in different knee positions in the coronal MR imaging plane. Meniscal displacement--that is, meniscal movement of 3 mm or more (in the medial direction for the medial meniscus, in the lateral direction for the lateral meniscus)--was compared with the patient's pain level as assessed with a visual analog scale by using analysis of variance.
  
  
  RESULTS
  Between the different knee positions, meniscal displacement of 3 mm or more (displaceable meniscal tears) was noted in 18 (42%) of 43 menisci with tears. Simultaneous occurrence of grade II or III ipsilateral collateral ligament lesions was present in all 18 displaceable meniscal tears, whereas a normal-appearing collateral ligament or collateral ligament lesion (grade I) was present in 22 of 25 nondisplaceable tears (P < .05). Displaced menisci most commonly had complex, radial, or longitudinal tear configurations (16 of 18, 89%). Patients with displaceable meniscal tears had significantly more pain than did patients with nondisplaceable meniscal tears (P < .001), independent of the concomitant knee abnormalities.
  
  
  CONCLUSIONS
  Displaceable meniscal tears usually have longitudinal, radial, or complex configurations; such tears are associated with substantial ipsilateral collateral ligament lesions and pain.
authors.affiliation: Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Larissa
authors.initials: L
authors.lastname: Boxheimer
authors.forename: Amelie M
authors.initials: AM
authors.lastname: Lutz
authors.forename: Marco
authors.initials: M
authors.lastname: Zanetti
authors.forename: Karl
authors.initials: K
authors.lastname: Treiber
authors.forename: Ludwig
authors.initials: L
authors.lastname: Labler
authors.forename: Borut
authors.initials: B
authors.lastname: Marincek
authors.forename: Dominik
authors.initials: D
authors.lastname: Weishaupt
mesh_terms: D000293:Adolescent; D000328:Adult; D017885:Collateral Ligaments / Q000293:injuries; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011187:Posture; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D000070600:Tibial Meniscus Injuries