title: Idiopathic synovial osteochondromatosis of the hip: radiographic and MR appearances in 15 patients.
abstract: OBJECTIVE
  To evaluate the radiographic and MR appearance of idiopathic synovial osteochondromatosis of the hip.
  
  
  METHODS
  Radiographs and MR images of 15 patients with idiopathic synovial osteochondromatosis of the hip were assessed. The former were analysed in terms of the presence of 1) juxta-articular calcified and/ or ossified bodies, 2) osteophytes, 3) bone erosion, 4) juxta-articular osteopenia, and 5) joint space narrowing, while for the latter, analysis focused on 1) the configuration of intra-articular bodies, 2) bone erosion, 3) synovial thickening, 4) conglomeration of intra-articular bodies, and 5) extra-articular extension.
  
  
  RESULTS
  At hip radiography, juxta-articular calcified and/ or ossified bodies were seen in 12 of the 15 patients (80%), bone erosion in eight (53%), osteophytes in seven (47%), juxta-articular osteopenia in five (33%) and joint space narrowing in five (33%). In eight patients (53%), MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, and areas of isointensity at T1WI and hyperintensity at T2WI. In three (20%), intra-articular bodies of focal low signal intensity and areas of hyperintensity at all pulse sequences were observed, with areas of iso-intensity at T1WI and hyperintensity at T2WI, while in four (27%), intra-articular bodies of only focal low signal intensity at all pulse sequences were apparent. Synovial thickening was present in 13 patients (87%), bone erosion in 11 (73%), conglomeration of the intra-articular bodies in 11 (73%), and an extra-articular herniation sac in six (40%).
  
  
  CONCLUSIONS
  The most common radiographic finding of synovial osteochondromatosis of the hip was the presence of juxta-articular calcified and/ or ossified bodies. MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, with areas of iso-intensity at T1WI and hyperintensity at T2WI. In addition, the presence of an extra-articular herniation sac was not uncommon.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Kangnamgu, Seoul, Korea.
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Suk Ju
authors.initials: SJ
authors.lastname: Hong
authors.forename: Ji Seon
authors.initials: JS
authors.lastname: Park
authors.forename: Jae Min
authors.initials: JM
authors.lastname: Cho
authors.forename: Eung Yeop
authors.initials: EY
authors.lastname: Kim
authors.forename: Joong Mo
authors.initials: JM
authors.lastname: Ahn
authors.forename: Youn Soo
authors.initials: YS
authors.lastname: Park
mesh_terms: D000328:Adult; D015838:Chondromatosis, Synovial / Q000175:diagnosis*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography