Conservative treatment of spontaneous osteonecrosis of the knee in the early stage: pulsed electromagnetic fields therapy

Eur J Radiol. 2013 Mar;82(3):530-7. doi: 10.1016/j.ejrad.2012.11.011. Epub 2012 Dec 3.


Hypothesis: pulsed electromagnetic fields treatment might improve symptoms in the early stage of spontaneous osteonecrosis of the knee.

Methods: Twenty-eight patients (19M/9F, age 49.8±16.4 years) suffering from symptomatic (pain) Koshino stage I spontaneous osteonecrosis of the knee, confirmed by magnetic resonance imaging (MRI) were treated with local pulsed electromagnetic fields therapy (6 h daily for 90 days). Clinical evaluation: baseline, 6- and 24-month follow-up by VAS for pain, knee society score (KSS), Tegner and EQ-5D scales. MRI evaluation: baseline and 6-month follow-up, measuring bone marrow lesion's areas and grading these lesions by WORMS score. Failures: patients undergoing knee arthroplasty.

Results: Pain significantly reduced at 6 months (from 73.2±20.7 to 29.6±21.3, p<0.0001), which remained almost unchanged at final follow-up (27.0±25.1). KSS significantly increased in first 6 months (from 34.0±13.3 to 76.1±15.9, p<0.0001) and was slightly reduced at final follow-up (72.5±13.5, p=0.0044). Tegner median level increased from baseline to 6-month follow-up (1(1-1) and 3(3-4), respectively, p<0.0001) and remained stable. EQ-5D improved significantly throughout the 24 months (0.32±0.33, baseline; 0.74±0.23, 6-month follow-up (p<0.0001); 0.86±0.15, 24-month follow-up (p=0.0071)). MRI evaluation: significant reduction of total WORMS mean score (p<0.0001) and mean femoral bone marrow lesion's area (p<0.05). This area reduction was present in 85% and was correlated to WORMS grading both for femur, tibia and total joint (p<0.05). Four failures (14.3%) at 24-month follow-up.

Conclusions: Pulsed electromagnetic fields stimulation significantly reduced knee pain and necrosis area in Koshino stage I spontaneous osteonecrosis of the knee already in the first 6 months, preserving 86% of knees from prosthetic surgery at 24-month follow-up. No correlation was found between MRI and clinical scores.

Level of evidence: Level IV; case series.

Publication types

  • Clinical Trial

MeSH terms

  • Aged
  • Arthralgia / diagnosis*
  • Arthralgia / etiology
  • Arthralgia / therapy*
  • Female
  • Humans
  • Knee Joint / pathology
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Osteonecrosis / complications
  • Osteonecrosis / diagnosis*
  • Osteonecrosis / therapy*
  • Pulsed Radiofrequency Treatment / methods*
  • Treatment Outcome