A Double-Blind, Placebo-Controlled Study of Ultrasound-Guided Pulsed Radiofrequency Treatment of the Saphenous Nerve for Refractory Osteoarthritis-Associated Knee Pain

Background: While the efficacy of pulsed radiofrequency (PRF) for shoulder pain has been demonstrated, its efficacy on the saphenous nerves for knee osteoarthritis ( OA)-associated pain has only been reported in observational studies. Objectives: The aim of this study was to compare saphenous nerve PRF to placebo for knee OA-associated pain. Study Design: Patients, practitioners, and outcome assessor-blinded randomized placebocontrolled trial. Setting: Pain management clinics at 2 hospitals in Japan. Methods: Patients were randomly allocated to the PRF (n = 37) or placebo group (n = 33). Patients aged 40-85 years with refractory anteromedial knee pain. PRF in the saphenous nerve under ultrasound guidance. The placebo group underwent the same procedure, but with motor stimulation. The primary endpoint was the average pain intensity measured using the visual analog scale (VAS) at the 12-week post-treatment visit; secondary outcomes included the average VAS at 1 and 4 weeks, and pain intensities at rest, in flexion, at standing, and at walking. Other secondary outcomes were knee pain, symptoms, activities of daily living, knee- related quality of life, mobility, range of motion, and adverse events. Results: In the PRF group, the mean VAS score was 52.41 +/- 26.17 at 12 weeks, while in the sham group, the mean VAS score was 63.06 +/- 27.12 ( P < 0.05). There were no significant differences between the groups in any of the secondary outcomes. Limitations: Patients with comorbidities were excluded from this study. The follow-up time was limited to 12 weeks. Conclusions: Ultrasound-guided saphenous nerve PRF proved to be effective for at least 12 weeks in patients with knee OA and showed no adverse events.