title: Spontaneous osteonecrosis of the knee (SONK).
abstract: OBJECTIVE
  Spontaneous osteonecrosis of the knee (SONK/Morbus Ahlback) mainly affects the medial condyle of elderly women. It is assumed that localized vascular insufficiency leads to necrosis of the subchondral bone with subsequent disruption of the nutrition supply to the cartilage above. The aetiology remains unclear in detail. Operative treatment procedures compete against non-operative strategies, whereas the outcome is unpredictable in many cases.
  
  
  METHODS
  A consecutive case series of five patients suffering from SONK was analysed. All patients underwent a clinical examination, magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry scan, as well as laboratory analyses and visual analogue scale (VAS) evaluation. Our treatment regime is based on high-dose vitamin D administered orally and intravenous application of 3 mg ibandronate two times within 8 weeks. Another 8 weeks later, all patients were followed up including a follow-up MRI.
  
  
  RESULTS
  Within 4 weeks, all patients were free of symptoms. The MRI follow-up showed remission of the bone marrow oedema in every case studied. VAS decreased significantly from 7.4 ± 1.0 pre-interventional to 0.8 ± 1.0 post-interventional. No allergic reactions or other side effects were documented.
  
  
  CONCLUSIONS
  We showed that our treatment regime not only eliminated the pathological findings in the MRI of all cases studied, but also decreased the pain level and functional limitations within a short-time period.
  
  
  METHODS
  IV.
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Breer
authors.forename: R
authors.initials: R
authors.lastname: Oheim
authors.forename: M
authors.initials: M
authors.lastname: Krause
authors.forename: R P
authors.initials: RP
authors.lastname: Marshall
authors.forename: M
authors.initials: M
authors.lastname: Amling
authors.forename: F
authors.initials: F
authors.lastname: Barvencik
mesh_terms: D061605:Administration, Intravenous; D000284:Administration, Oral; D050071:Bone Density Conservation Agents / Q000008:administration & dosage; D004164:Diphosphonates / Q000008:administration & dosage; D005260:Female; D005269:Femur; D006801:Humans; D000077557:Ibandronic Acid; D007717:Knee; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000175:diagnosis* / Q000188:drug therapy*; D014807:Vitamin D / Q000008:administration & dosage
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D014807:Vitamin D; D000077557:Ibandronic Acid