Spontaneous Osteonecrosis of the Knee: Systematic review & Delphi Study

Abstract

Background: Numerous treatments for Spontaneous Osteonecrosis of the Knee (SONK) have been described, but there is little guidance regarding which joint-preserving treatments to use for different disease stages.

Aims: To assess the effectiveness and appropriateness of non-operative and operative joint-preserving treatments for SONK as a whole, as well as for different disease stages.
Methodology: A systematic review with narrative synthesis of four bibliographic databases was undertaken to identify studies evaluating the effectiveness (clinical, radiological outcomes and failure rates) of joint-preserving treatment for SONK. The findings of the review were then used to inform a 2-round Delphi study involving an international expert panel to establish consensus on preferred first and second-line treatments for different disease stages.
Results: Twenty eligible studies were identified: 8 described non-operative measures and 14 surgical interventions (2 studies described several treatments). One study was a randomised controlled trial evaluating foot orthoses, which proved more effective than usual treatment with analgesia and physiotherapy. Supportive treatment with analgesia and restricted weight bearing, bisphosphonates and most other joint-preserving surgical interventions had promising results from small case series.
Nineteen experts contributed to the first round of the Delphi study and 14 to the second round. Consensus was achieved for 3 months of rest and analgesia as first-line treatment in early and intermediate-stage disease, without consensus on the most appropriate second-line treatment. For late-stage disease, consensus was not reached for first-line treatment although 50% agreed against joint-preserving therap. For second-line treatment, 78.6% would use arthroplasty.
Conclusions: Rest and analgesia with or without restricted weight-bearing appears to be an appropriate, and often effective first-line treatment for early or intermediate-stage disease. Arthroplasty, rather than joint-preserving therapy is the most commonly utilised treatment for late-stage disease. However, existing research is limited, and higher-level evidence is required before being able to definitively state which joint-preserving treatments are most effective for SONK of different stages.