RFA or Chemical Neurolysis of the Genicular Nerves Compared to Conservative Treatment for Knee Pain Caused by OA

A randomised controlled triall (RCT) with three parallel arms comparing the functional outcome of chemical ablation with phenol and radiofrequency ablation (RFA) of the genicular nerves with conservative treatment in patients with chronic knee pain caused by osteoarthritis (OA).

In guidelines for knee osteoarthritis (OA), conservative treatments are physical therapy, analgesics and intra-articular injections with corticosteroids. In severe OA and persisting symptomatic cases the golden standard is joint replacing surgery. A less invasive technique is ablation of the sensory (genicular) nerves of the knee. This technique is beneficial for younger patients as a bridge to surgery or patients that cannot undergo total knee arthroplasty (TKA) due to comorbid health conditions. Nerve ablation can either be done with chemical agents or thermal energy.

Although there are numerous studies on genicular nerve block for chronic knee pain caused by OA, there are just a few small studies that compare genicular nerve block with conservative treatment.To be able to determine if genicular nerve ablation is efficacious to serve the gap between conservative treatment and TKA, this randomised controlled trial (RCT) compares two forms of genicular nerve ablation (radiofrequency and phenolisation; intervention) with conservative treatment (control) up to 6 months after treatment.

Eligibility Criteria:
Inclusion Criteria:

1. Adult patients of both sexes, \>35 years who are not a candidate for TKA due to young age, old age, comorbidity or technical reasons.
2. OKS \< 30 on a scale from 0 (severe function) to 48 points (satisfactory function).
3. Continued pain in the target knee that is moderate to severe (defined as NRS ≥ 6 on an 11-point NRS scale) either constantly or with motion despite at least 3 months of conservative treatments. Conservative treatment can include: active physiotherapy, pharmacological treatment of pain (acetaminophen or NSAIDs) and intra-articular corticosteroid infiltration.
4. Radiologic confirmation of arthritis for the target knee. Defined as the Kellgren Lawrence (KL) score of 2 or more on X-ray or MRI.

Exclusion Criteria:

1. Patient with prior ablation of the genicular nerves, prior partial, resurfacing, or TKA of the target knee (residual hardware).
2. Patient with a history of neurovascular injury or recent trauma of the lower extremities.
3. Patient with chronic widespread pain.
4. Polyneuropathy and/or radicular pain in the lower extremities.
5. Patient is currently implanted with a neurostimulator.
6. Local or systemic infection (bacteraemia).
7. Uncontrolled immune suppression.
8. Intra-articular injections (steroids, hyaluronic acid, platelet enriched plasma, stem cell, ...) in the target knee within 90 days from randomisation.
9. Arthroscopic debridement/lavage into the target knee within 180 days from randomisation.
10. BMI\<18,5 kg/m2 and patients with minimal subcutaneous tissue thickness that would not accommodate ablation with phenol or radio frequency (risk of skin burns).
11. Allergies to products used during the procedure (lidocaine, phenol, contrast dye).
12. Patients who have a planned TKA in the near future, defined as patients who already have agreed on a date for the TKA procedure.
13. Patients with psychosocial problems as determined by the investigator.