Bipolar RFA Versus Phenol Neurolysis for Knee Osteoarthritis Pain

Saglik Bilimleri Universitesi69 enrolled

Overview

This prospective observational comparative study evaluates the analgesic efficacy and safety of ultrasound-guided bipolar radiofrequency ablation (BPRFA) versus phenol chemical neurolysis (PCN) of the genicular nerves in patients with chronic knee osteoarthritis (gonarthrosis) refractory to conservative treatment. Patients with moderate-to-severe chronic knee pain who demonstrate significant pain relief following diagnostic genicular nerve block undergo either BPRFA or PCN targeting the superior medial, superior lateral, and inferior medial genicular nerves under ultrasound guidance. Pain intensity and functional outcomes are assessed using the Numeric Rating Scale (NRS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and during follow-up evaluations at 4, 12, and 24 weeks after treatment. The study aims to compare pain reduction, functional improvement, responder rates, and procedure-related adverse events between the two treatment modalities.

Knee osteoarthritis (gonarthrosis) is a common cause of chronic knee pain and functional limitation, especially in older adults. Although conservative treatments such as physical therapy, oral analgesics, and intra-articular injections are commonly used, many patients continue to experience persistent pain and reduced quality of life. In recent years, minimally invasive genicular nerve interventions have become important alternatives for patients who do not achieve adequate benefit from conservative management or are not suitable candidates for surgery. Radiofrequency ablation (RFA) of the genicular nerves has been shown to reduce pain and improve function in patients with chronic knee osteoarthritis. Bipolar radiofrequency ablation (BPRFA), which uses two closely positioned radiofrequency cannulas, may create larger lesions and provide broader denervation compared with conventional monopolar techniques. Phenol chemical neurolysis (PCN) is another minimally invasive treatment option that provides chemical denervation of the genicular nerves and may represent a simpler and more cost-effective alternative. However, concerns remain regarding the potential for unintended spread of phenol and procedure-related complications. The aim of this prospective observational comparative study is to compare the analgesic efficacy, functional outcomes, and safety profiles of ultrasound-guided BPRFA and PCN in patients with chronic knee osteoarthritis who are refractory to conservative treatment. Patients with chronic moderate-to-severe unilateral knee pain and radiologically confirmed osteoarthritis first undergo diagnostic genicular nerve block under ultrasound guidance. Patients who achieve significant pain relief after the diagnostic block subsequently receive either BPRFA or PCN as part of routine clinical practice. Pain severity and functional status are evaluated using the Numeric Rating Scale (NRS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and during follow-up visits at 4, 12, and 24 weeks after treatment. The study also compares treatment response rates and procedure-related adverse events between the two interventions.

Interventions

Phenol Chemical NeurolysisPROCEDURE

Ultrasound-guided phenol neurolysis was performed targeting the superior medial, superior lateral, and inferior medial genicular nerves. Following confirmation of needle placement, 2 mL of 8% phenol was injected around each targeted genicular nerve.

Ultrasound-Guided Bipolar Radiofrequency AblationPROCEDURE

Ultrasound-guided bipolar radiofrequency ablation was performed using two parallel radiofrequency cannulas placed within 1 cm of each other targeting the superior medial, superior lateral, and inferior medial genicular nerves. Radiofrequency ablation was applied at 80°C for 90 seconds following sensory and motor stimulation testing.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 75 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Adults aged 18 to 75 years * Unilateral moderate-to-severe knee pain due to gonarthrosis * Numeric Rating Scale (NRS) score ≥6 * Knee pain lasting longer than 6 months * Radiological diagnosis of knee osteoarthritis, Kellgren-Lawrence grade 2-4 * Failure of conservative treatments, including analgesic medications, physical therapy, or intra-articular injections * At least 50% pain relief after diagnostic genicular nerve block * Ability to provide written informed consent Exclusion Criteria: * Knee pain due to causes other than osteoarthritis, such as fracture, trauma, spinal disorder, or inflammatory arthritis * Previous knee surgery * Knee joint effusion detected on physical examination or ultrasound * Cognitive impairment * Hepatic or renal failure * Severe psychiatric disorder * Local or systemic infection * Coagulopathy * Current use of antiplatelet or anticoagulant therapy * Presence of a pacemaker * Intra-articular injection or interventional knee procedure within the previous 6 months

Outcomes

Primary Outcomes

Change in Pain Intensity

Pain intensity was assessed using the Numeric Rating Scale (NRS). Changes in NRS scores from baseline were evaluated after ultrasound-guided bipolar radiofrequency ablation and phenol chemical neurolysis of the genicular nerves.

Time frame: Baseline, 4 weeks, 12 weeks, and 24 weeks

Secondary Outcomes

Functional improvement

Functional outcomes and quality of life were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), including total, pain, stiffness, and function subscale scores.

Time frame: Baseline, 4 weeks, 12 weeks, and 24 weeks

Proportion of Patients Achieving ≥50% Reduction in NRS Scores

Treatment response was defined as a reduction of at least 50% in Numeric Rating Scale (NRS) scores compared with baseline values following treatment.

Time frame: 12 weeks and 24 weeks

Procedure-related complications

The incidence of procedure-related adverse events and complications was recorded throughout the follow-up period.

Time frame: Up to 24 weeks