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

Background: 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 perpendicular to 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.