Genicular Nerve Radiofrequency Ablation Versus Hyaluronic Acid Injection for Knee Osteoarthritis Pain (RF-PROSPECTIU)

Ultrasound-guided diagnostic block of the superomedial, superolateral and inferomedial genicular nerves with 1 ml of 1% lidocaine per nerve. Participants with at least 50% pain reduction within 4 hours undergo ultrasound-guided thermal radiofrequency ablation of the same three nerves (80 C for 90 seconds per nerve) in a single session. Participants with a negative block do not receive radiofrequency and are withdrawn from the study.

Ultrasound-guided thermal radiofrequency ablation (80 C, 90 seconds per nerve) of the superomedial, superolateral and inferomedial genicular nerves, performed only after a positive diagnostic block (>=50% pain reduction within 4 hours after 1 ml of 1% lidocaine per nerve).

Single intra-articular injection of 6 ml of high molecular weight hyaluronic acid (hylan G-F 20, Synvisc-One, or similar) into the index knee.

Single 6 ml intra-articular injection of high molecular weight hyaluronic acid into the index knee.

Pain during movement (walking or climbing stairs) in the index knee, measured on a 100 mm visual analogue scale and recorded in cm with one decimal (0 = no pain, 10 = worst imaginable pain). Higher scores indicate worse pain.

Pain at rest in the index knee, measured on a 100 mm visual analogue scale and recorded in cm with one decimal (0 = no pain, 10 = worst imaginable pain). Higher scores indicate worse pain.

Western Ontario and McMaster Universities Osteoarthritis Index (Likert 3.1). Total score 0-96 and subscales for pain (0-20), stiffness (0-8) and physical function (0-68). Higher scores indicate worse symptoms and function.

Percentage of participants with a reduction of at least 2 points from baseline in pain during movement (visual analogue scale, 0-10).

Number of days with analgesic use in the previous 4 weeks (0-28) and most potent analgesic used (none, paracetamol, NSAID, weak opioid, strong opioid).

Adverse events related to the diagnostic block, radiofrequency ablation or hyaluronic acid injection, systematically recorded at each visit.

Proportion of participants requiring retreatment, rescue treatment (including corticosteroid injection) or indication of total knee arthroplasty, and time to first retreatment or rescue treatment.

EQ-5D-5L descriptive system (5 dimensions, 5 levels; utility index calculated with the Spanish value set, where 1 = full health and higher values indicate better health) and EQ-VAS (0-100, higher scores indicate better health).

Percentage of participants allocated to the radiofrequency arm with less than 50% pain reduction within 4 hours after the diagnostic block, who therefore do not receive radiofrequency ablation.

Patient global assessment of the impact of knee osteoarthritis, measured on a 100 mm visual analogue scale (0 = very well, 100 = very poor). Higher scores indicate worse status.

Single 7-point item from "very much better" to "very much worse" compared with before the study treatment. Responders are participants reporting "much better" or "very much better".

Responder according to OMERACT-OARSI criteria, based on pain during movement, WOMAC physical function and patient global assessment, each expressed on a 0-100 scale: improvement in pain or function >=50% and >=20 points, or improvement >=20% and >=10 points in at least two of the three domains.