Pulsed Radiofrequency Application on Femoral and Obturator Nerves for Hip Joint Pain: Retrospective Analysis with 12-Month Follow-up Results.

BACKGROUND: Osteoarthritis of the hip joint is a common cause of pain and disability. Patients not responding to conservative management often cannot undergo joint replacement due to the presence of multiple comorbidities, while some other patients prefer to postpone surgery as long as possible. Radiofrequency denervation of articular branches of the femoral and obturator nerves, which supply innervation of the joint, is a novel technique to reduce hip joint pain. Previous studies reported positive results after application of continuous radiofrequency to the target nerves; however, this approach carries the potential risk of neuritis and neuroma formation. Pulsed radiofrequency (PRF) is a safer alternative to continuous radiofrequency not creating necrosis but a complex neuromodulatory effect on target nerves. There is no published evidence of PRF efficacy after 3 month follow-up.

OBJECTIVES: This single-center study objective was to evaluate the short and medium term effectiveness of PRF on the femoral articular branches and obturator nerves in patients with chronic hip pain.

STUDY DESIGN: Retrospective single-center study.

SETTING: Italian National Health Service Public Hospital.

METHODS: Retrospective analysis of 14 patients treated with PRF for severe hip joint pain (mean numericAL rating scale (NRS) 7.7 ± 1.2 mean Oxford Hip Score (OHS) 20 ± 8.4). Mean pain and disability scores were evaluated with NRS and OHS respectively at 1, 3, 6 and 12-month follow-up. Mean pain and disability scores were evaluated with NRS and OHS respectively at 1, 3, 6, and 12-month follow-up. All patients were treated with pulsed radiofrequency applied under fluoroscopy on the articular branches of the femoral and obturator nerves for 300 seconds each.

RESULTS: Eight patients out of 14 (57%) reported an NRS reduction > 50% at 1 month post procedure. Overall, both pain and disability scores were significantly (P < 0.01) lower at all follow-up until 6 months, mean NRS at 1, 3, and 6 months was 3.6 ± 3; 4.1 ± 3.3; 4.8 ± 2.9 while OHS was 37.6 ± 17.7; 35.8 ± 17.7; 35.8 ± 14 respectively. At 12 months, NRS was 5.8 ± 2.4 while OHS 23.3 ± 12.7, it must be pointed out that even if both scores are significantly (P < 0.01) lower than basal, only 3 patients out of 14 (21%) maintained a NRS reduction > 50% from basal at 12 months post procedure. We reported 2 femoral artery punctures without any significant complication.

LIMITATIONS: Retrospective study, small sample size.

CONCLUSIONS: Pulsed radiofrequency is a safe and effective modality to treat hip joint pain in the short and medium term. Definition of positive outcome predictors is required to reserve radiofrequency treatment only for those patients who can benefit from this procedure.

KEY WORDS: Hip joint pain, pulsed radiofrequency, obturator nerve, femoral nerve, interventional pain management, radiofrequency.