Phenol Neurolysis and Radiofrequency Thermocoagulation in Knee Arthroplasty Surgery

Comparison of the Efficacy of Phenol Neurolysis and Radiofrequency Thermocoagulation Applied to the Geniculate Nerve on Pain in Patients Undergoing Knee Arthroplasty Surgery

Patients who presented to the Department of Neurology, Algology, and underwent knee arthroplasty surgery for chronic knee osteoarthritis between 2025 and 2026 and underwent radiofrequency or chemical neurolysis of the geniculate nerve due to pain will be studied in two groups. The groups will be randomly assigned by the clinician using computer-aided designation, and the patients will be allocated to the two groups. Patients in Group 1 will receive radiofrequency thermocoagulation of the geniculate nerve. Patients in Group 2 will receive phenol neurolysis of the geniculate nerve. Patients with pacemakers will be included in the phenol neurolysis group (Group 2), and patients with a phenol allergy will be included in the radiofrequency group (Group 1).

During the study, NRS and WOMAC measurements will be performed on patients in Groups 1 and 2 to assess pain intensity before the procedure and at 1, 3, and 6 months post-procedure. Neurological and musculoskeletal system examinations will be performed during routine check-ups before the procedure and at 1, 3 and 6 months after the procedure, and any developing side effects will be recorded.

Study Overview

• Status: Active, not recruiting
• Conditions: Knee Osteoarthritis; Arthroplasty; Radiofrequency
• Intervention / Treatment: Procedure: genicular nerve radiofrequency thermocoagulation and fenole neurolysis

Detailed Description

140 patients who underwent arthroplasty for chronic knee osteoarthritis will be evaluated in the Algology Department of the Neurology Department at Adnan Menderes University Hospitals between October 2025 and May 2026. Inclusion criteria include patients over the age of 18 who underwent arthroplasty for chronic knee osteoarthritis. Written informed consent will be obtained from all participants. Patients with severe systemic diseases, local infections, or injuries, and those allergic to any of the injection materials will be excluded. All patients will be clinically evaluated (a detailed history, including personal data, medical history, and current treatments). Procedural procedures will be performed in a sterile operating room environment. Patients are positioned supine, and a pillow is placed under the popliteal fossa to support the knee. After visualizing the tibiofemoral joint with fluoroscopy, the potential locations of the geniculate nerves in the medial and lateral regions of the distal femur and medial tibia will be identified with fluoroscopy. After sterile conditions are achieved, local anesthesia is administered both subcutaneously and transcutaneously. A 5 cm long, 5 mm active tip RFT cannula (NeuroThermTM, Medipoint GmbH, Hamburg, Germany) is placed for each geniculate nerve using anteroposterior and lateral fluoroscopy images. For the superior lateral geniculate nerve, it is advanced toward the attachment of the femoral shaft and lateral condyle, for the superior medial geniculate nerve toward the distal femoral diaphysis, and for the inferior medial geniculate nerve toward the proximal tibial diaphysis and medial tibial condyle, ensuring bone contact. The cannula is positioned midline between the diaphysis of the femur and tibia using the lateral image. Sensory stimulation at 50 Hz and motor stimulation at 2 Hz are then applied, followed by a 2 cc 0.5% bupivacaine block for each geniculate nerve. Each cannula is lesioned for 90 seconds using an 80-degree conventional RFT generator (Neurotherm NT1100 / 13001-12).

In the phenol neurolysis group, a 22-gauge, 3.5-inch Quincke needle is advanced toward the junction of the femoral shaft and lateral condyle for the superior lateral genicular nerve; toward the distal femoral diaphysis for the superior medial genicular nerve; and toward the proximal tibial diaphysis and medial tibial condyle for the inferior medial genicular nerve, ensuring bone contact. Lateral imaging confirms the cannula's position in the midline of the diaphysis of the femur and tibia. A mixture of 6 cc of 0.25% bupivacaine and 6% phenol is injected into each geniculate nerve. Post-procedure complications and side effects (infection, bleeding, neurological deficit, etc.) are recorded. Patient response will be determined according to the reduction in pain at follow-up visits at 1, 3, and 6 months after the procedure as follows: good responders will be evaluated as >50% reduction, poor responders will be evaluated as <50% reduction, or no change will be evaluated as non-responders.

• Study Type: Interventional
• Enrollment (Estimated): 140
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Efeler/Aydın
    • Aydin, Efeler/Aydın, Turkey (Türkiye), 09100
      • Esra Ertilav

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Inclusion criteria were patients over the age of 18 who had undergone arthroplasty for chronic knee osteoarthritis.Exclusion Criteria:

Exclusion Criteria:

Patients with severe systemic diseases, local infections or injuries, and those allergic to any of the injection materials were excluded from the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group 1; patients to whom applied radiofrequency thermocoagulation	Procedure: genicular nerve radiofrequency thermocoagulation and fenole neurolysis; After visualizing the tibiofemoral joint with fluoroscopy, the potential locations of the geniculate nerves in the medial and lateral regions of the distal femur and medial tibia will be identified with fluoroscopy. A 5 cm long, 5 mm active tip RFT cannula (NeuroThermTM, Medipoint GmbH, Hamburg, Germany) is placed for each geniculate nerve using anteroposterior and lateral fluoroscopy images. Sensory stimulation at 50 Hz and motor stimulation at 2 Hz are then applied, followed by a 2 cc 0.5% bupivacaine block for each geniculate nerve. Each cannula is lesioned for 90 seconds using an 80-degree conventional RFT generator (Neurotherm NT1100 / 13001-12). In the phenol neurolysis group, a 22-gauge, 3.5-inch Quincke needle is advanced toward the junction of the femoral shaft and lateral condyle for the superior lateral genicular nerve. A mixture of 6 cc of 0.25% bupivacaine and 6% phenol is injected into each geniculate nerve; Other Names: fenole neurolysis
Experimental: Group 2; patients to whom applied chemical neurolysis	Procedure: genicular nerve radiofrequency thermocoagulation and fenole neurolysis; After visualizing the tibiofemoral joint with fluoroscopy, the potential locations of the geniculate nerves in the medial and lateral regions of the distal femur and medial tibia will be identified with fluoroscopy. A 5 cm long, 5 mm active tip RFT cannula (NeuroThermTM, Medipoint GmbH, Hamburg, Germany) is placed for each geniculate nerve using anteroposterior and lateral fluoroscopy images. Sensory stimulation at 50 Hz and motor stimulation at 2 Hz are then applied, followed by a 2 cc 0.5% bupivacaine block for each geniculate nerve. Each cannula is lesioned for 90 seconds using an 80-degree conventional RFT generator (Neurotherm NT1100 / 13001-12). In the phenol neurolysis group, a 22-gauge, 3.5-inch Quincke needle is advanced toward the junction of the femoral shaft and lateral condyle for the superior lateral genicular nerve. A mixture of 6 cc of 0.25% bupivacaine and 6% phenol is injected into each geniculate nerve; Other Names: fenole neurolysis

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Efficacy of both methods on knee surgery patients	Patients undergoing knee arthroplasty surgery for chronic knee osteoarthritis will be evaluated with the Numerical Rating Scale (NRS) before the intervention and at 1, 3, and 6 months after the procedure. A decrease in NRS of 50% or more will be considered significant.	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety of both methods on knee surgery patients	The aim of this study was to determine the side effects and complications of phenol and radiofrequency applications to the geniculate nerve in patients undergoing knee arthroplasty surgery for chronic knee osteoarthritis. Neurological and musculoskeletal examinations will be performed during routine checkups before and at 1, 3, and 6 months after the procedure in patients undergoing knee arthroplasty surgery for chronic knee osteoarthritis, and any developing side effects will be recorded.	12 months

Collaborators and Investigators

• Sponsor: Aydin Adnan Menderes University

Study record dates

Study Major Dates

• Study Start (Actual): September 15, 2025
• Primary Completion (Estimated): March 1, 2026
• Study Completion (Estimated): June 1, 2026

Study Registration Dates

• First Submitted: January 20, 2026
• First Submitted That Met QC Criteria: January 25, 2026
• First Posted (Actual): February 2, 2026

Study Record Updates

• Last Update Posted (Actual): February 2, 2026
• Last Update Submitted That Met QC Criteria: January 25, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: 2025/280

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No