title: Paralabral cysts in the hip joint: findings at MR arthrography.
abstract: OBJECTIVE
  The purpose of this research was to retrospectively characterize paralabral cysts of the hip as seen at MR arthrography.
  
  
  METHODS
  After Institutional Review Board approval, 704 patients who had MR arthrography were identified over a 3-year period and 40 patients were identified as having a cyst or fluid collection at the hip by MR report. MR images from these 40 patients were retrospectively reviewed by three radiologists where 18 were found to have a paralabral cyst, which were characterized as follows: location, configuration, contrast filling, size of the cyst, extent, direction, and whether associated osseous changes were present. In addition, the acetabular labrum was assessed for tears and, if present, the location and pattern were characterized.
  
  
  RESULTS
  Paralabral cysts were located anterosuperiorly in 56%, anteriorly in 22%, posterosuperiorly in 17%, and anteroinferiorly in 6% of cases. The vast majority (94%) were multilocular and filled with intra-articular contrast medium. The average dimensions were 8 × 7 × 11 mm. The paralabral cyst demonstrated extracapsular extension in 72% of cases, with 39% located between the ilium and gluteus minimus, and 22% between the ilium and iliopsoas. Remodeling of the ilium adjacent to the cyst was observed in 50% of these cases. A labral tear was at the base of the labrum adjacent to the cyst in 78% of cases, while the tear was isolated to the body of the labrum in 22%. Tears were most commonly anterosuperior (55%) or anterior (28%) in location.
  
  
  CONCLUSIONS
  Our results show that paralabral cysts of the hip are most commonly located anterosuperiorly, are multilocular, fill with intra-articular contrast medium, have average dimensions up to 11 mm, and often extend extracapsularly between muscle and bone where they may remodel the adjacent ilium.
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: Gandikota
authors.initials: G
authors.lastname: Girish
authors.forename: Monica Kalume
authors.initials: MK
authors.lastname: Brigido
authors.forename: Asheesh
authors.initials: A
authors.lastname: Bedi
authors.forename: David
authors.initials: D
authors.lastname: Fessell
mesh_terms: D000293:Adolescent; D000328:Adult; D003560:Cysts / Q000473:pathology*; D005260:Female; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007592:Joint Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult