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.

Pulsed radiofrequency treatment of articular branches of femoral and obturator nerves for chronic hip pain.

PURPOSE: Chronic hip pain is a common symptom experienced by many people. Often, surgery is not an option for patients with multiple comorbidities, and conventional drugs either have many side effects or are ineffective. Pulsed radiofrequency (PRF) is a new method in the treatment of pain. We attempt to compare the efficacy of PRF relative to conservative management for chronic hip pain. PATIENTS AND METHODS: Between August 2011 and July 2013, 29 patients with chronic hip pain were divided into two groups (PRF and conservative treatment) according to consent or refusal to undergo PRF procedure. Fifteen patients received PRF of the articular branches of the femoral and obturator nerves, and 14 patients received conservative treatment. Visual analog scale (VAS), Oxford hip scores (OHS), and pain medications were used for outcome measurement before treatment and at 1 week, 4 weeks, and 12 weeks after treatment. RESULTS: At 1 week, 4 weeks, and 12 weeks after treatment initiation, improvements in VAS were significantly greater with PRF. Improvements in OHS were significantly greater in the PRF group at 1 week, 4 weeks, and 12 weeks. Patients in the PRF group also used less pain medications. Eight subjects in the conservative treatment group switched to the PRF group after 12 weeks, and six of them had >50% improvement. CONCLUSION: When compared with conservative treatment, PRF of the articular branches of the femoral and obturator nerves offers greater pain relief for chronic hip pain and can augment physical functioning.

Withdrawal reflexes in adductor muscles elicited by electrical and magnetic stimulation of the obturator nerve.

The withdrawal reflex in the short head of the biceps femoris muscle after electrical stimulation of the sural nerve at the ankle has been investigated in numerous studies. These studies have described two distinct responses: early (R-II) and late (R-III). However, withdrawal reflex activity of the adductor muscles in the legs has not been studied systematically. Adductor muscle reflex activity is important because it can produce serious clinical problems, such as adductor spasticity and spasms, during bladder surgery. The present study examined withdrawal reflex features of adductor muscles obtained by electrical and magnetic stimulation of the obturator nerve (ON) in 34 normal healthy subjects. Early adductor muscle withdrawal reflex responses were elicited by ipsilateral ON electrical stimulation with a mean latency of 45.7+/-2.0 ms (responses in 94% of subjects). Reflex responses were also obtained using magnetic stimulation at a similar incidence rate. Contralateral ON electrical stimulation resulted in a similar reflex, but with a lower incidence. ON and femoral nerve electrical and magnetic coil stimulation produced similar low-incidence responses in the vastus medialis. These findings indicate that short latency adductor withdrawal reflexes are easily obtained on both sides following electrical or magnetic stimulation of the ON, and they can be elicited by both nociceptive and nonnociceptive stimuli. These reflexes prepare the body for a proper response to incoming signals and likely serve to protect the pelvic floor and pelvic organs.

Radiological anatomy of the obturator nerve and its articular branches: basis to develop a method of radiofrequency denervation for hip joint pain.

OBJECTIVE: A previous study of radiofrequency neurotomy of the articular branches of the obturator nerve for hip joint pain produced modest results. Based on an anatomical and radiological study, we sought to define a potentially more effective radiofrequency method. DESIGN: Ten cadavers were studied, four of them bilaterally. The obturator nerve and its articular branches were marked by wires. Their radiological relationship to the bone structures on fluoroscopy was imaged and analyzed. A magnetic resonance imaging (MRI) study was undertaken on 20 patients to determine the structures that would be encountered by the radiofrequency electrode during different possible percutaneous approaches. RESULTS: The articular branches of the obturator nerve vary in location over a wide area. The previously described method of denervating the hip joint did not take this variation into account. Moreover, it approached the nerves perpendicularly. Because optimal coagulation requires electrodes to lie parallel to the nerves, a perpendicular approach probably produced only a minimal lesion. In addition, MRI demonstrated that a perpendicular approach is likely to puncture femoral vessels. Vessel puncture can be avoided if an oblique pass is used. Such an approach minimizes the angle between the target nerves and the electrode, and increases the likelihood of the nerve being captured by the lesion made. Multiple lesions need to be made in order to accommodate the variability in location of the articular nerves. CONCLUSIONS: The method that we described has the potential to produce complete and reliable nerve coagulation. Moreover, it minimizes the risk of penetrating the great vessels. The efficacy of this approach should be tested in clinical trials.