title: MR imaging of transient osteoporosis of the hip: an update on 155 hip joints.
abstract: OBJECTIVE
  Transient osteoporosis of the hip (TOH) presents with acute onset pain and bone marrow edema (BMe) on MR imaging. The purpose of this study is to revise the MR imaging characteristics of TOH by analyzing the data derived from 155 hip examinations. We also sought to explore the relationship between the duration of symptoms and the presence of sparing and subchondral fractures.
  
  
  METHODS
  MR images of 155 hips (141 TOH patients) were retrospectively evaluated for the presence of insufficiency fractures and the morphology of BMe. Sparing of the medial bone marrow of the femoral head was recorded together with demographic and clinical data. Progression to regional migratory osteoporosis (RMO) and postpartum cases were also recorded.
  
  
  RESULTS
  Our population consisted of 76.4% male and 23.6% female patients. RMO progression was recorded in 19.4% and 4 postpartum cases displayed bilateral disease. Sparing of the medial bone marrow was present at 87.7% of patients and disappeared as the disease progressed (P=0.005). BMe was restricted within the femoral head in 11.0%, extended to the femoral neck in 40% and to the femoral shaft in 49% of the cases studied. Subchondral fractures were present at 48.7% of the hips.
  
  
  CONCLUSIONS
  This study describes TOH patient characteristics, the MR imaging findings (BMe pattern, microfractures), their association with symptom duration and the chance of progressing to RMO.
authors.affiliation: Department of Medical Imaging, University Hospital of Heraklion, Medical School, University of Crete, Greece.
authors.forename: Michail E
authors.initials: ME
authors.lastname: Klontzas
authors.affiliation: Department of Medical Imaging, University Hospital of Heraklion, Medical School, University of Crete, Greece.
authors.forename: Evangelia E
authors.initials: EE
authors.lastname: Vassalou
authors.affiliation: Department of Anatomy, University of Thessalia, Medical School, Larissa, Greece.
authors.forename: Aristeidis H
authors.initials: AH
authors.lastname: Zibis
authors.affiliation: Department of Radiology, "Papageorgiou" General Hospital of Thessaloniki, Greece.
authors.forename: Antonia S
authors.initials: AS
authors.lastname: Bintoudi
authors.affiliation: Department of Medical Imaging, University Hospital of Heraklion, Medical School, University of Crete, Greece. Electronic address: akarantanas@gmail.com.
authors.forename: Apostolos H
authors.initials: AH
authors.lastname: Karantanas
mesh_terms: D000328:Adult; D000368:Aged; D001855:Bone Marrow Diseases / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005272:Femur Neck / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis* / Q000473:pathology; D058866:Osteoporotic Fractures / Q000473:pathology*; D012189:Retrospective Studies
keywords: Bone marrow edema; Hip; Regional migratory osteoporosis; Transient osteoporosis