title: Shifting bone marrow edema of the knee.
abstract: OBJECTIVE
  The purpose of our study is to describe shifting bone marrow edema in the knee as the MR imaging feature of intra-articular regional migratory osteoporosis of the knee.
  
  
  METHODS
  Five men, aged 45-73 years, were referred by orthopedic surgeons for MR imaging evaluation of knee pain, which had been present for 2 weeks to 6 months. One patient had a prior history of blunt trauma. None had risk factors for osteonecrosis. Four patients had two MR examinations and the patient with prior blunt trauma had four. Plain radiographs were obtained in all patients.
  
  
  RESULTS
  In all cases, a large area of marrow edema initially involved a femoral condyle, with migration of the bone marrow edema to the other femoral condyle, tibia, and/or patella occurring over a 2- to 4-month period. Adjacent soft tissue edema was present in all five patients, while none had a joint effusion. Radiographs of two patients showed generalized osteopenia.
  
  
  CONCLUSIONS
  In the absence of acute trauma or clinical suspicion of infection, a large area of bone marrow edema without a zone of demarcation may represent intra-articular regional migratory osteoporosis. Demonstration of shifting bone marrow edema on follow-up examinations suggests this diagnosis.
authors.affiliation: Department of Radiology, North Shore University Hospital, 300 Community Drive, Manhasset, NY 11030, USA.
authors.forename: Josh B
authors.initials: JB
authors.lastname: Moosikasuwan
authors.forename: Theodore T
authors.initials: TT
authors.lastname: Miller
authors.forename: Kevin
authors.initials: K
authors.lastname: Math
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Schultz
mesh_terms: D000368:Aged; D001855:Bone Marrow Diseases / Q000175:diagnosis*; D004487:Edema / Q000175:diagnosis*; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis*