Interventional symptomatic treatment of knee osteoarthritis using ablation of the nerves surrounding the knee joint
| ISRCTN | ISRCTN84066069 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN84066069 |
| Sponsor | University of Patras |
| Funder | University of Patras |
- Submission date
- 07/06/2026
- Registration date
- 15/06/2026
- Last edited
- 15/06/2026
- Recruitment status
- Recruiting
- Overall study status
- Ongoing
- Condition category
- Musculoskeletal Diseases
Plain English summary of protocol
Background and study aims
Osteoarthritis (OA) is a degenerative joint disease involving the cartilage and many of its surrounding tissues. While total knee arthroplasty is an effective treatment option for end-stage knee arthritis and persistent severe pain, the relatively slow progression of the disease allows for a stepwise algorithmic approach in management using non-surgical treatment options. Through the wide array of non-surgical treatment options, cooled radiofrequency ablation has been proposed.
Radiofrequency ablation (RFA) is the process of thermal nerve degradation through a probe providing radiofrequency energy. Cooled radiofrequency ablation (CRFA) uses a water supply system to internally cool the RFA probe. While the internally cooled probes operate at a temperature of 60°C, the temperature of the surrounding tissues reaches 80°C, thus providing a larger lesion around the probe. The procedure aims to disrupt the transmission of pain signals from the osteoarthritic knee via the genicular nerves.
The primary objective of this study is to evaluate the efficacy of CRFA at 1-, 3-, and 6-months post-intervention in patients with painful knee OA using a numerical rating pain scale (NRPS).
Who can participate?
What does the study involve?
Three groups of patients would be investigated: group CRFA4 = classical anatomical targets (4 nerves), group CRFA6 = revised and classical anatomical targets (6 nerves) and group CRFA8 = Additional (IPBSN & RFN), Revised and Classical anatomical targets (8 nerves).
The secondary objectives are the comparison of safety and tolerability of the interventions, as well as the patient’s clinical outcome questionnaires at 3- and 6-months post-intervention.
What are the possible benefits and risks of participating?
The benefits are immediate relief of pain, avoidance of a complex surgery especially in older patients with medical comorbidities. The risks of participating are few, as it is a minimally invasive technique on an outpatient basis without serious complications.
Where is the study run from?
University of Patras, Greece.
When is the study starting and how long is it expected to run for?
September 2025 to June 2027
Who is funding the study?
The Patras University and Patras University Hospital, Greece.
Who is the main contact?
Prof Andreas Panagopoulos, andpan21@gmail.com, anpanagop@med.upatras.gr
Contact information
Principal investigator, Scientific, Public
Patras University Hospital
Patras
26504
Greece
| Phone | +306944363624 |
|---|---|
| anpanagop@med.upatras.gr |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Randomized controlled trial |
| Masking | Blinded (masking used) |
| Control | Active |
| Assignment | Parallel |
| Purpose | Treatment |
| Participant information sheet | 49668_PIS [Greek].pdf |
| Scientific title | Classic vs New Anatomical Targets for Cooled Radiofrequency Ablation of the Genicular Nerves in the Symptomatic Management of Knee Osteoarthritis: A Prospective, Randomized, Double-Blind Clinical Trial |
| Study acronym | CRFAKA |
| Study objectives | The primary objective of our proposed randomized trial is to evaluate the efficacy of CRFA at 1- 3- and 6-months post-intervention in patients with painful KOA using the Numerical Rating Pain Scale (NRPS). Three groups of patients would be investigated: group CRFA4 = classical anatomical targets (4 nerves), group CRFA6 = revised and classical anatomical targets (6 nerves) and group CRFA8 = Additional (IPBSN & RFN), Revised and Classical anatomical targets (8 nerves). The secondary objectives are the comparison of safety and tolerability of the interventions, as well as the patient’s clinical outcome at 3- and 6-months post-intervention, using the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), the Oxford Knee Score (OKS), the SF-12 and the Forgotten Joint Score (FJS). |
| Ethics approval(s) |
Approved 10/05/2021, Bioethics Committee of Patras University (University Campus, building A, pATRAS, 26504, Greece; +30 2610 997245; uprescom@upatras.gr), ref: 11846/05/10/2021 |
| Health condition(s) or problem(s) studied | Moderated osteoarthritis of the knee joint |
| Intervention | Patients will be placed on the radiolucent table at the Department of Interventional Radiology in a supine position with a bolster under the knee to produce 30ο of flexion; this position flattens the suprapatellar joint space, thus minimizing needle trespass, and also allows for an unobstructed lateral view of the knee. The treated knee will be draped and sterilized in a standard manner. Patients will be continuously monitored and administered conscious sedation (1–2 mg IV midazolam and/or fentanyl 25–100 mcg IV) and supplemental oxygen. Fluoroscopic images will be obtained to align the femur in an anteroposterior (AP) view to target the genicular nerves at locations above the femoral condyles and for the IMGN, a greater caudal tilt of the fluoroscope will be obtained to square off the tibial plateau for an appropriate AP view. A sealed and opaque envelope will be brought to the operating theatre, dictating the group of each patient. The location of the nerves (SLGN, SMGN, IMGN, MRGN, IPBSN and RFN) will be identified using fluoroscopy, according to previously described methods. Two to 3 ml of 1% lidocaine is used to anesthetize the skin and subcutaneous tissues before cannula insertion at each target site under fluoroscopic guidance. Thereafter, a 75 mm, 17-gauge introducer needle will be placed to ablate the targeted nerves. One milliliter of 2% lidocaine will be injected through the introducer needles to anesthetize the area before ablation. After placement of the introducer needle, an 18-gauge, internally cooled 4-mm active tip RFA electrode (Coolief, Halyard Health, Alpharetta, GA, USA) will be placed into the introducer needle, and the positioning is checked again using fluoroscopy. The introducer is connected to the COOLIEF* Cooled RF Advanced Generator that allows staggered start, stop and adjustment of 4 independent channels. The cooled radiofrequency ablation (CRFA) probes will be advanced, and ablation will be performed with lesion settings at 60 °C (80–90 °C adjacent tissue temperature) for 2.5 min. As mentioned before, this type of ablation creates a spherical lesion at the tip of the probe. Cooled RF electrodes include a thermocouple at the active electrode tip to provide a temperature-controlled lesion formation. This involves water-cooling of the active electrode tip during the duration of the process without tissue charring at the electrode tip; this mechanism doubles the lesion radius and increases the lesion volume by 5 times. |
| Intervention type | Procedure/Surgery |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 30/06/2027 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 45 Years |
| Upper age limit | 90 Years |
| Sex | All |
| Target sample size at registration | 200 |
| Total final enrolment | 75 |
| Key inclusion criteria | Patients of either sex will participate in the clinical trial as long as they have: 1. The NICE clinical criteria of primary knee OA for one or both knees: 1.1. Age >45 years 1.2. Activity-related joint pain 1.3. No morning joint stiffness or morning stiffness that lasts no longer than 30 minutes 2. Radiological confirmation of knee arthritis (grade ≥2) according to the Kellgren and Lawrence classification 3. Chronic knee pain for a minimum duration of 6 months 4. Pain intensity ≥4 on the (NRPS) 5. Lack of pain relief from conventional therapy, including nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, muscle relaxants, oral steroids, physical therapy, and intra-articular injection therapy. 6. The ability to communicate in Greek |
| Key exclusion criteria | 1. inflammatory or post-traumatic knee arthritis 2. Patients who have received CRFA treatment in the past 3. Injection of hyaluronic acid or corticosteroid within the previous 3 months 4. Significant structural deformities affecting locomotion and knee function aside from osteoarthritis and which might cause chronic knee pain 5. Body mass index ≥40 kg/m² 6. Uncontrolled serious disease (cancer, diabetes, end-stage heart disease etc) 7. Unstable psychiatric illness 8. Coagulopathy or bleeding disorders 9. Active systemic or local infection |
| Date of first enrolment | 01/09/2025 |
| Date of final enrolment | 31/12/2026 |
Locations
Countries of recruitment
- Greece
Study participating centre
Patras
26504
Greece
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan | The datasets generated and/or analyzed during the current study will be published as a supplement to the subsequent results publication |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Other files | 08/06/2026 | No | No | ||
| Participant information sheet | 08/06/2026 | No | Yes | ||
| Protocol file | 08/06/2026 | No | No |
Additional files
- 49668_Protocol.pdf
- Protocol file
- 49668_PIS [Greek].pdf
- Participant information sheet
- 49668_Consent form [Greek].pdf
- Other files
Editorial Notes
15/06/2026: Study’s existence confirmed by the Research Ethics Committee (REC) of Patras University Hospital, Greece.
