Cocogen Trial: COoled Versus COnventional Radiofrequency Treatment of the GENicular Nerves for Chronic Knee Pain

Knee osteoarthritis is a progressive degenerative process that affects joint cartilage and the subchondral bone. Approximately 10% to 30% of all osteoarthritis patients suffer from disabling symptoms such as pain, stiffness and loss of function leading to psychological and sleeping disorders and a diminished quality of life. When conservative treatment fails to treat the symptoms, a total knee arthroplasty can be performed. However, this procedure is not suitable for all patients. For these specific groups of patients a radiofrequent treatment of the genicular nerves might be an alternative treatment option. Multiple researchers investigated the effect of conventional and later also, cooled radiofrequent treatment of the genicular nerves, with promising results for both techniques. However, the techniques have never been compared in a randomised controlled trial. This study is designed to assess the feasibility of conducting a large RCT comparing pain relief and costs after a conventional radiofrequency treatment of the genicular nerves (superomedial, superolateral and inferomedial) versus a cooled radiofrequency treatment.

This pilot study is designed as a prospective, multicentre, double blind, randomised controlled non-inferiority trial. The total follow up time is 6 months with follow up assessments at 1, 3 and 6 months post intervention. It is estimated that the total duration of data collection will cover 1 year. Adult patients (\> 18 years) with chronic, moderate to severe knee pain (NRS\>4) due to osteoarthritis, radiological diagnosed to be graded 2-4 according to the Kellgren-Lawrence criteria or with persistent postoperative moderate to severe knee pain (NRS\>4) after total knee arthroplasty can be included in the study.

Patients will be randomly selected for treatment with conventional radiofrequent treatment or cooled radiofrequent treatment of the SL, SM and IL genicular nerves. In total, three hospitals participate in this study: Ziekenhuis Oost-Limburg (Belgium), Maastricht UMC+ (Netherlands) and Rijnstate (Netherlands).

Eligibility Criteria:
Inclusion Criteria:

* Age ≥ 18 years
* Able to understand the informed consent form and provide written informed consent and able to complete outcome measures.
* Chronic anterior knee pain (\> 12 months) with an NRS \> 4 on most or all days for the index knee either constantly or with motion.
* Unresponsive to conventional treatments continued during 12 months including physiotherapy, oral analgesics or intra-articular infiltrations.
* Radiologic confirmation of arthritis of OA grade of 2 (mild), 3 (moderate) or 4 (severe) noted within 6 months for the index knee according the Kellgren Lawrence criteria (27) diagnosed by an independent radiologist with experience in musculoskeletal imaging or patients with total knee arthroplasty of the index knee with a negative orthopaedic workout.
* Other therapies (including surgical interventions) for pain in the index knee are allowed for the period of the study follow up as long as they are documented. This is necessary to correctly estimate the costs in the cost effectiveness analyses. Allowing patients to receive additional treatments will also improve the protocol compliance.
* Agree to provide informed consent and to comply with the requirements of this protocol for the full duration of the study

Exclusion Criteria:

* Patient refusal to comply to protocol procedures or schedule
* Local or systemic infection (bacteraemia)
* Evidence of inflammatory arthritis or an inflammatory systemic disease responsible for knee pain
* Intra-articular injections (steroids, hyaluronic acid, platelet enriched plasma, ...) in the index knee during the 3 months prior to procedure
* Body mass index (BMI) \> 40 kg/m2
* Pregnant, nursing or planning to become pregnant Chronic widespread pain before the treatment
* Patients with psychosocial dysfunction will be referred for further psychological follow up prior to possible inclusion
* Allergies to products used during the procedure
* Uncontrolled coagulopathy defined as supratherapeutic dose of anticoagulation medication.
* Uncontrolled immune suppression
* Participating in another clinical trial/investigation within 30 days prior to signing informed consent
* Patient is currently implanted with a defibrillator, neuromodulator or other electrical devices
* Radicular pain in index leg
* Patient received previous conventional or cooled radiofrequency of the index knee