Continuous Radiofrequency in Hip Osteoarthritis Pain: A Randomized Clinical Trial.

Procedures will be performed in the surgical block of Hospital SARAH, Brasília unit, using an aseptic technique.

All participants will undergo sedation or general anesthesia using a laryngeal mask airway, according to the preference of the anesthetist in the room. The procedure will be performed with the participant positioned in dorsal decubitus, on a radiolucent table, with a small pillow below the knees to promote a slight flexion of 10 to 20 degrees of the hips, leading to relaxation of the joint capsule.

The surgeon will be positioned at the side of the surgical table, facing the affected hip, with the scoping device on the contralateral side, aligned at 90 degrees with the patient, allowing the visualization of anteroposterior images of the affected hip.

For the control group (IAI), a 22G spinal needle will be used, positioned in the anteroposterior direction towards the central portion of the femoral neck, which will be introduced until it trespasses the anterior hip capsule through tactile sensitivity. After verifying the correct positioning with the use of fluoroscopy and infusion of 3 milliliters (ml) of iodinated contrast diluted at 50% (Iomeron® 300, Patheon Italia S.p.A. Ferentino - Italy), an infiltration of 4 ml of 1% Ropivacaine (Ropi®, Cristália, Itapira - São Paulo, Brazil) and 80mg of methylprednisolone 40mg/ml (Predi-Medrol®, União Química, Brasília - Federal District, Brazil) will be performed, totalizing 6 ml of solution.

In the intervention group (IA + CRF), radiofrequency ablation will be performed with the aid of a 22-gauge cannula (Diros Technology Inc, Markham, Ontario, Canada), 10 or 15 cm long, with a 10-mm curved active tip, at a temperature of 90º for 90 seconds. The cannula will be introduced in the region just above the tip of the greater trochanter, lateral to a descending line originating in the anterior superior iliac spine (ASIS), and directed to the medial border of the patella (ASIS - patella). Its introduction will take place in the anteroposterior and lateromedial direction, to reach the region lateral to the anatomical reference known as the teardrop, with an angle of about 20 to 30 craniocaudal degrees about a transverse line on the axis of the thigh. The denervation of the articular branches of the Obturator Nerve (NO) will be performed in 2 cycles, at a temperature of 90 degrees for 90 seconds, starting lateral to the lateral edge of the obturator foramen and inferior to the teardrop, with subsequent repositioning of the cannula about 1 cm lateral to the first point. Both lesions will be preceded by motor stimulation at 2.5 volts (V) to exclude motor branches within the range of action of the active tip followed by the infusion of 2ml of 1% ropivacaine. Then, the cannula will be repositioned in a more cranial location, 2 to 3 cm lateral to the ASIS-patella line, parallel to the superolateral edge of the acetabular dome, to reach the sensory branches of the Femoral Nerve (NF), performing three cycles (from medial to lateral) at the 01, 12, and 11 o'clock positions. The most medial lesion will be preceded by motor stimulation at 2.5 V to exclude motor branches within the active tip's range of action. All three cycles will be followed by 2 ml of 1% ropivacaine infusion. After completion of radiofrequency ablation, IAI of the hip will follow as described for the control group above.

Inclusion criteria

• Individuals ≥ 18 years of age, with symptomatic unilateral hip osteoarthritis, grades II and III according to the Kellgreen and Lawrance classification, hip pain for more than six months (medial, anterior, anterolateral, and/or lateral region) will be included.

Exclusion criteria

• Individuals with radiculopathy and ipsilateral irradiation, osteonecrosis of the femoral head, previous arthroplasty on the hip to be studied or surgical scar that could lead to changes in the anatomy of the hip, cases of high dislocation of the hip, pain exclusively in the posterior region, symptomatic ipsilateral knee osteoarthritis, intra-articular infiltration of corticosteroids or hyaluronic acid in the hip for less than six months, patients with neurological diseases, peripheral neuropathy or psychiatric diseases, use of a pacemaker or Prothrombin Activity Time (INR) > 3.