title: MR diagnosis of posterior root tears of the lateral meniscus using arthroscopy as the reference standard.
abstract: OBJECTIVE
  The purpose of our study was to determine whether tears of the posterior root of the lateral meniscus can be diagnosed using standard MR criteria of a meniscal tear in the presence or absence of an anterior cruciate ligament (ACL) tear.
  
  
  METHODS
  From a series of 559 knee MR examinations with arthroscopic correlation, we selected all 16 proven tears isolated to the posterior root of the lateral meniscus for retrospective blinded review, along with 45 cases of arthroscopically intact lateral meniscal posterior roots. The reviewers categorized whether there was a torn, possibly torn, or intact root based on three specific coronal and three specific sagittal image locations.
  
  
  RESULTS
  When all possibly torn roots were considered as torn, the sensitivity and specificity for diagnosis of a root tear were 93% and 89%, respectively. The observers' overall diagnosis of a tear based on all images gave a higher combined sensitivity and specificity than if the diagnosis of a tear had been based on one or any combination of the three coronal and three sagittal locations. Root tears were significantly more common in the presence of an ACL tear (p < 0.0001), but the presence or absence of an ACL tear did not change MR diagnostic accuracy.
  
  
  CONCLUSIONS
  The standard MR criteria of meniscal distortion and signal to the surface can be used to diagnose lateral meniscal root tears. The presence or absence of an ACL tear did not change diagnostic accuracy.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Arthur A
authors.initials: AA
authors.lastname: De Smet
authors.forename: Donna G
authors.initials: DG
authors.lastname: Blankenbaker
authors.forename: Richard
authors.initials: R
authors.lastname: Kijowski
authors.forename: Ben K
authors.initials: BK
authors.lastname: Graf
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shinki
mesh_terms: D000328:Adult; D000368:Aged; D000070598:Anterior Cruciate Ligament Injuries; D001182:Arthroscopy; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000070600:Tibial Meniscus Injuries