Genicular Nerve Radiofrequency Ablation

Key Takeaways

• Minimally invasive treatment that thermally lesions the knee’s sensory genicular nerves to help control chronic osteoarthritis pain.

• A diagnostic genicular nerve block that delivers ≥50% pain relief lasting ≥24 hours predicts benefit from ablation.

• Common targets are the superior medial, superior lateral, and inferior medial genicular nerves, placed under fluoroscopic guidance.

• Lesions are made with radiofrequency heat (≈80°C for ~60 seconds per target); cannulas are often adjusted to enlarge the treated area.

• Real-world results show about half of patients achieve ≥50% pain reduction and many experience meaningful functional improvement.

What Genicular Nerve Radiofrequency Ablation Is and How It Works

What is genicular nerve radiofrequency ablation and how does it relieve knee pain? It’s a minimally invasive procedure that reduces pain signals by thermally lesioning the sensory nerves serving the knee. A diagnostic genicular nerve block is done first; a temporary ≥50% reduction in pain suggests the ablation will help. Under fluoroscopy guidance, needles are positioned at standard targets—most often the superior medial, superior lateral, and inferior medial genicular nerves—and radiofrequency energy (conventional or cooled) heats tissue (about 80°C for ~60 seconds per target) to create focused lesions. Performed under local anesthesia with or without light sedation, the treatment lowers nociceptive transmission from the joint and can provide relief that lasts months to years. Repeat ablation is an option if pain returns.

Who Is a Candidate and Who Is Not

Eligibility for genicular nerve radiofrequency ablation depends on symptom duration, response to diagnostic blocks, and treatment goals. Typical candidates have chronic knee pain from osteoarthritis that hasn’t responded to conservative care and who get ≥50% relief from a genicular nerve block lasting at least 24 hours. A two-step pathway—diagnostic block(s) then ablation—helps identify those most likely to benefit.

Preparing for the Procedure and What to Expect

Preparing for genicular nerve radiofrequency ablation typically involves a short diagnostic phase followed by the fluoroscopy-guided procedure that treats three genicular nerves to confirm and address the pain source. The diagnostic block uses 1 mL injections at the superior lateral, superior medial, and inferior medial nerves; ≥50% pain reduction for ≥24 hours signals likely candidacy. On the day of the procedure, fluoroscopic guidance ensures accurate cannula placement with AP and lateral views. Sensory testing (≈50 Hz) checks proximity, motor testing (2 V, 2 Hz) confirms safety, and lesioning (80°C for ~1 minute per site) follows, often with small cannula adjustments to enlarge the lesion. Afterward, expect short monitoring, simple incision care, icing, limited activity for 24–48 hours, and follow-up to track pain relief.

Step-by-Step Procedure and Technical Considerations

Once diagnostic blocks and routine pre-procedure checks are complete, the operator places and tests cannulas under fluoroscopic guidance. Three cannulas target the superior lateral, superior medial, and inferior medial genicular nerves with true lateral diaphyseal midpoint confirmation. A diagnostic sensory test at ≈50 Hz confirms proximity; motor testing at 2 V, 2 Hz stops the procedure if activation occurs. After local lidocaine and a brief 90-second wait, thermal lesions are created (80°C for 60 seconds per lesion); cannulas are then advanced 3–5 mm and re-ablated to widen the treated area. Conventional and cooled RF techniques differ in temperature and timing. Finally, 1 mL methylprednisolone is often injected through each cannula before removal and dressing.

Benefits, Risks, and Real-World Outcomes

How effective is genicular nerve radiofrequency ablation (GNRFA) for chronic knee pain? In real-world outcomes from 134 patients followed for about 23 months, 47.8% achieved ≥50% NRS reduction and 61.2% had a ≥2-point improvement; 59.0% reported being “much improved” on the PGIC. The protocol used prognostic diagnostic blocks (≥50% relief) before ablation and compared cooled versus conventional RF. Benefits include durable pain reduction for roughly half of patients and improved overall function for many. Risks are those common to percutaneous RF procedures—temporary pain, infection, bleeding, and procedure failure. Factors linked to better outcomes included higher radiographic OA (Kellgren–Lawrence 2–4), not being on active opioids/antidepressants/anxiolytics, and targeting all three genicular nerves.