title: Treatment of spontaneous osteonecrosis of the knee (SPONK) by a bisphosphonate.
abstract: OBJECTIVE
  Primary spontaneous osteonecrosis of the knee is a painful lesion in the elderly without any known cause. The onset of pain is usually acute. The prognosis is poor with high frequency of osteoarthritis, joint surface collapse, and subsequent knee surgery. In the present study, we determined whether bisphosphonates can prevent the joint surface collapse by delaying the post-necrotic remodeling.
  
  
  METHODS
  Between 2006 and 2009, 17 consecutive patients (mean age 68 years) with clinical and radiographic signs of knee osteonecrosis were identified and given alendronate, 70 mg perorally, once a week for a minimum of 6 months. The patients were followed clinically, radiographically, and by MRI.
  
  
  RESULTS
  10 of the 17 patients did not develop osteoarthritis (group A), 4 patients developed mild osteoarthritis but no knee joint surface collapse (group B), and 3 patients had a joint surface collapse (group C). 2 of the 3 patients in group C-as compared to none in the other groups-stopped medication prematurely, due to side effects.
  
  
  CONCLUSIONS
  Compared to a previous, untreated series of osteonecrosis patients at our hospital, the clinical results in the present series appeared better. 59% of the patients had a complete radiographic recovery, as compared to 25% in the original study. 12% were failures regarding need to undergo surgery when bisphosphonates were given, as compared to 32% in the previous untreated series. An anticatabolic drug delaying the remodeling might be an effective treatment in osteonecrosis of the knee but further (preferably randomized) studies are necessary.
authors.affiliation: Department of Orthopedics, Clinical Sciences, Lund University and Skåne University Hospital, Lund, Sweden. jan.jureus@telia.com
authors.forename: Jan
authors.initials: J
authors.lastname: Jureus
authors.forename: Anders
authors.initials: A
authors.lastname: Lindstrand
authors.forename: Mats
authors.initials: M
authors.lastname: Geijer
authors.forename: David
authors.initials: D
authors.lastname: Roberts
authors.forename: Magnus
authors.initials: M
authors.lastname: Tägil
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use*; D004164:Diphosphonates / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000517:prevention & control*; D010020:Osteonecrosis / Q000150:complications / Q000188:drug therapy*
chemical_list: D004164:Diphosphonates; D019386:Alendronate