Cooled Radiofrequency Neurotomy of the Articular Sensory Branches of the Obturator and Femoral Nerves - Combined Approach Using Fluoroscopy and Ultrasound Guidance: Technical Report, and Observational Study on Safety and Efficacy.

BACKGROUND: Chronic hip joint pain is a common condition with an estimated prevalence of 7% in men and 10% in women, in a population sample aged over 45. Conservative treatment can include physical therapy, weight loss, a variety of pharmacologic agents ranging from nonsteroidal antiinflammatory drugs (NSAIDS) to opioids, and intraarticular injections with various substances. Definitive treatment of hip pain, however, has primarily centered on hip arthroplasty.

OBJECTIVE: We describe a novel anterior approach to cooled radiofrequency (RF) hip denervation under combined ultrasound (US) and fluoroscopy guidance to avoid the neurovascular femoral bundle and reach proper landmarks.

STUDY DESIGN: Retrospective chart review of consecutive cases.

SETTING: Interventional Pain Management urban private practice.

METHODS: Data on 52 RF ablations of the hip in 23 patients were retrospectively collected. RF ablation was conducted with patient supine and under guidance of fluoroscopy and US. While fluoroscopy was used to place RF probes to appropriate landmarks, sole purpose of using US was to avoid femoral neurovascular bundle. Data were collected on needle placement, stimulation parameters, and short- and long-term complications.

RESULTS: A total of 62 patients underwent 2 diagnostic blocks. Fifty-two of them had greater than 50% relief and agreed to RF ablation. Until now, the ablation was conducted in 23 patients. There were no adverse events, except one case of neuritis. Expectedly, the needle approach to the lateral articular branches of the femoral nerve was easily achieved with more than a 1 cm passage distance from the femoral nerve in all 52 RF cases (median 2.5 range 1-3.5 cm). Placement of the second trocar to the incisura acetabuli was more challenging; in 21 RF cases the passing distance was less than 1 cm (range 0.5 to 1.9 cm, median 0.8). Motor stimulation (2 Hz) at less than 1 V was positive for the obturator nerve in 26 cases, which resulted in electrode repositioning more laterally (2-5 mm). Change in the pain scores was from the baseline 7.61 ± 1.2 to 2.25 ± 1.4 after the RF ablation (P < 0.01). The time interval of pain relief was much longer for RF ablation.

LIMITATIONS: Limitations of this retrospective, observational study include lack of blinding and absence of a comparator group. We did not attempt to wean opioids in our patient population.

CONCLUSIONS: An anterior needle approach to the lateral articular branches of the femoral and obturator nerves, and subsequently RF denervation of these nerves, is a safe procedure when US needle guidance is combined with identification of landmarks using fluoroscopy.

KEY WORDS: Chronic hip pain, radiofrequency ablation, hip denervation.