title: Characterization and pathological characteristics of spontaneous osteonecrosis of the knee.
abstract: OBJECTIVE
  Spontaneous osteonecrosis of the knee affects patients typically over the age of fifty-five years. Evidence exists that this process may not be true necrosis. The purpose of this study was to characterize the demographic, radiographic, and pathologic features of this condition.
  
  
  METHODS
  Twenty-one patients (twenty-two knees) consecutively treated for spontaneous osteonecrosis of the knee were studied.
  
  
  RESULTS
  Only one of twenty-two specimens demonstrated evidence of bone necrosis. No specimens showed fat necrosis, marrow necrosis, fibrous change or appositional bone repair. Fourteen of twenty-two specimens (64%) showed significant osteopenia and fifteen of twenty-two specimens (68%) showed evidence of osteoarthritis.
  
  
  CONCLUSIONS
  This study demonstrated that spontaneous osteonecrosis of the knee is not an osteonecrotic condition and has been misnamed. Osteopenia and osteoarthritis may play a role in the pathogenesis of this disease.
authors.affiliation: Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Mears
authors.forename: Edward F
authors.initials: EF
authors.lastname: McCarthy
authors.forename: Lynne C
authors.initials: LC
authors.lastname: Jones
authors.forename: David S
authors.initials: DS
authors.lastname: Hungerford
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mont
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001851:Bone Diseases, Metabolic / Q000150:complications; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications; D010020:Osteonecrosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology*; D011859:Radiography; D012189:Retrospective Studies