title: Prevalence of the acetabular sublabral sulcus at MR arthrography in patients under 17 years of age: does it exist?
abstract: OBJECTIVE
  To retrospectively determine characteristics of contrast-filled acetabular labral clefts in patients under the age of 17 years at MR arthrography (Mra) correlated with arthroscopy, which may impact the thinking regarding the existence of a sublabral sulcus.
  
  
  METHODS
  After IRB approval, 41 patients under the age of 17 who had MRa were identified. The following observations of contrast-filled clefts were assessed: (1) presence/absence, (2) location, (3) depth, (4) abnormal signal within the labrum and (5) shape (linear, gaping, complex). Fisher's exact and the Wilcoxon matched-pairs signed-rank test were performed. Interreader agreement was calculated with Cohen's k.
  
  
  RESULTS
  Reader 1 found clefts in 41 %. Depth was less than half in 6%, more than half in 65% and full thickness in 29%. Shape was linear in 53%, gaping in 18% and complex in 29%. Signal changes occurred in 88%. Reader 2 found clefts in 29%. Depth was less than half in 17%, more than half in 58% and full thickness in 25%. Shape was linear in 50%, gaping in 42% and complex in 17%. Signal changes occurred in 50%. None of the clefts fulfilled the criteria for a sublabral sulcus at MRa and arthroscopy.
  
  
  CONCLUSIONS
  None of the clefts found in our subjects under the age of 17 years met the MRa and arthroscopy criteria for a sublabral sulcus, which supports the theory that such clefts represent labral tears.
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI, 48109-5326, USA, dr.o.magerkurth@gmail.com.
authors.forename: Olaf
authors.initials: O
authors.lastname: Magerkurth
authors.forename: Jon A
authors.initials: JA
authors.lastname: Jacobson
authors.forename: Yoav
authors.initials: Y
authors.lastname: Morag
authors.forename: David
authors.initials: D
authors.lastname: Fessell
authors.forename: Asheesh
authors.initials: A
authors.lastname: Bedi
authors.forename: Jon K
authors.initials: JK
authors.lastname: Sekiya
mesh_terms: D000077:Acetabulum / Q000293:injuries* / Q000473:pathology*; D000293:Adolescent; D001175:Arthrography / Q000379:methods; D002648:Child; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D050724:Fractures, Cartilage / Q000473:pathology*; D025981:Hip Injuries / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity