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Knee

Treatment of spontaneous osteonecrosis of the knee (SPONK) by a bisphosphonate

A prospective case series with 17 patients

, , , &
Pages 511-514 | Received 18 Apr 2012, Accepted 09 Jun 2012, Published online: 24 Sep 2012
 

Abstract

Background and purpose 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.

Patients and 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.

Interpretation 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.

JJ: planning, collection and interpretation of data, statistics, and writing of the article. AL: project setup, collection and interpretation of data, and revision of the manuscript. MG: evaluation of imaging studies, interpretation of data, and revision of the manuscript. DR: collection and interpretation of data and revision of the manuscript. MT: project setup, planning, collection and interpretation of data, statistics, and writing of the article.

The project was supported by the Swedish Research Council (project 2031), the Greta and Johan Kock Foundation, the Alfred Österlund Foundation, the Maggie Stephens Foundation, the Thure Carlsson Foundation, and the Medical Faculty of Lund. The study was performed without support from the manufacturers of the drug.

No competing interests declared.