Comparison of Conventional and Cooled Radiofrequency of the Genicular Nerves in Patients With Chronic Knee Pain

In this three-arm, pragmatic, prospective, multicentre, double blind, randomised sham-controlled trial of approximately 4 years duration, 400 patients with chronic moderate to severe anterior knee pain (>12 months) refractory to conventional treatments will be included. Two groups of chronic knee pain patients will be enrolled depending on the aetiology of knee pain: OA and PPSP. Each patient will undergo a run-in period of 1 to 3 months depending on the previous treatments of the patient. A run-in period is added to the trial to guarantee that conservative treatment is performed in an optimal way before randomisation. In each group (osteoarthritis and persistent post-surgical pain), non-responders to the run-in period will be randomly allocated to a conventional RF intervention of the genicular nerves, a cooled RF intervention of the genicular nerves or a sham procedure in a 2:2:1 ratio. The patients will be followed up for a period of 2 years.

Inclusion criteria

• Signed written informed consent must be obtained before any study assessment is performed.
• Adult patients (Age ≥ 18 years old).
• Chronic anterior knee pain (> 12 months) that is moderate to severe (defined as NRS > 4 on most or all days for the index knee either constantly or with motion at time of screening and, an average NRS score reported in the patient diary >4 at the end of the run-in period).
• Unresponsive (meaning insufficient pain reduction or intolerance) to conventional treatments ongoing for at least 12 months prior to inclusion. Conventional treatments must include all of the following: active physiotherapy, pharmacological treatment of pain and intra-articular corticosteroid infiltration.
• Only for patients with Osteoarthritis (OA): Radiologic confirmation of knee osteoarthritis of grade 2 (mild), 3 (moderate) or 4 (severe) noted within 12 months prior to the screening for the index knee according the Kellgren Lawrence criteria diagnosed by an independent radiologist with experience in musculoskeletal imaging on radiography (Rx) or magnetic resonance imaging (MRI). If imaging will need to be performed at screening it is recommended to perform an MRI instead of Rx. Imaging with MRI will enable the independent radiologist to perform a better estimation of the grade of OA.
• Only for patients with Persistent Post-Surgical Pain (PPSP) after Total Knee Arthroplasty (TKA): Patients with PPSP* after TKA need to have had a negative orthopaedic work-up

Exclusion criteria

• 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.
• Pregnant, nursing or planning to become pregnant before the study intervention. Participants who become pregnant after the study intervention during the follow-up period will not be excluded.
• Chronic widespread pain.
• Patients with unstable psychosocial disorder.
• Allergies to products used during the procedure (lidocaine, propofol, chlorhexidine).
• 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 neurostimulator.
• Current radicular pain in index leg.
• Previous conventional or cooled radiofrequency of the index knee.
• Patients with bilateral knee pain defined as chronic knee pain (> 12 months) in both knees that is moderate to severe (defined as a numeric rating scale (NRS) > 4 on most or all days either constantly or with motion) and that is unresponsive (meaning insufficient pain reduction or intolerance) to conventional treatments ongoing for at least 12 months prior to inclusion. Conventional treatments must include all of the following: active physiotherapy, pharmacological treatment of pain and intra-articular corticosteroid infiltration.
• Patients who have a planned TKA in the near future defined as patients who already have agreed on a date for the TKA procedure.
• Patients who are unwilling or mentally incapable to complete the study questionnaires.