title: Classification and localization of acetabular labral tears.
abstract: OBJECTIVE
  The purpose of this study was to compare the findings on hip MR arthrography (MRA) with the published MRA and arthroscopic classifications of hip labral tears and to evaluate a clock-face method for localizing hip labral tears.
  
  
  METHODS
  We retrospectively reviewed 65 hip MRA studies with correlative hip arthroscopies. Each labrum was evaluated on MRA using the classification system of Czerny and an MRA modification of the Lage arthroscopic classification. In addition, each tear was localized on MRA by using a clock-face description where 6 o'clock was the transverse ligament and 3 o'clock was anterior. These MRA findings were then correlated with the arthroscopic findings using the clock-face method of localization and the Lage arthroscopic classification of labral tears.
  
  
  RESULTS
  At MRA, there were 42 Czerny grade 2 and 23 grade 3 labral tears and 22 MRA Lage type 1, 11 type 2, 22 type 3 and 10 type 4 tears. At arthroscopy, there were 10 Lage type 1 flap tears, 20 Lage type 2 fibrillated tears, 18 Lage type 3 longitudinal peripheral tears and 17 Lage type 4 unstable tears. The Czerny MRA classification and the modified MRA Lage classification had borderline correlation with the arthroscopic Lage classification. Localization of the tears using a clock-face description was within 1 o'clock of the arthroscopic localization of the tears in 85% of the patients.
  
  
  CONCLUSIONS
  The Lage classification, which is the only published arthroscopic classification system for hip labral tears, does not correlate well with the Czerny MRA or an MRA modification of the Lage classification. Using a clock-face description to localize tears provides a way to accurately localize a labral tear and define its extent.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA. dg.blankenbaker@hosp.wisc.edu
authors.forename: D G
authors.initials: DG
authors.lastname: Blankenbaker
authors.forename: A A
authors.initials: AA
authors.lastname: De Smet
authors.forename: J S
authors.initials: JS
authors.lastname: Keene
authors.forename: J P
authors.initials: JP
authors.lastname: Fine
mesh_terms: D000077:Acetabulum / Q000293:injuries* / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D001175:Arthrography / Q000379:methods; D001182:Arthroscopy; D005260:Female; D050724:Fractures, Cartilage / Q000145:classification / Q000175:diagnosis*; D025981:Hip Injuries / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012421:Rupture / Q000175:diagnosis; D012680:Sensitivity and Specificity