LDRT vs. Genicular Nerve Ablation (RFA) for Knee Pain

Knee arthritis patients have two non-surgical options that work in completely different ways. Genicular nerve ablation, also called radiofrequency ablation or RFA, quiets the nerves that carry pain signals from the knee. Low-dose radiation therapy, or LDRT, aims a small amount of radiation at the joint itself to calm inflammation. Both are aimed at people who want to delay or avoid knee replacement. Here is what each does, and where each fits.

What Genicular Nerve Ablation Does

Genicular nerve ablation is a needle-based outpatient procedure. Using ultrasound or fluoroscopy for guidance, the doctor places a thin probe next to the sensory nerves that run along the outside of the knee, the genicular nerves. Radiofrequency current heats the probe tip, and that heat disrupts the nerve's ability to send pain signals to the brain^[1]. The targets are sensory nerves, not the nerves that move your leg^[2].

It is usually a two-step process. First comes a diagnostic nerve block: the doctor numbs the nerves with lidocaine and checks whether the pain drops. If you get at least 50 percent pain relief for at least 24 hours, you qualify for the ablation itself^[3]. The procedure is done under local anesthesia. It does not require general anesthesia.

It is reserved for people with knee osteoarthritis who have not responded to conservative treatment and who are poor candidates for knee replacement, unwilling to have it, or still have pain after a replacement^[3].

The trial evidence is solid. In a multicenter randomized trial of cooled radiofrequency ablation, 65 percent of patients had at least 50 percent pain reduction at 12 months, with an average drop of 4.3 points on a 0 to 10 pain scale, and 75 percent reported improved effects^[4]. A second multicenter trial comparing cooled RFA to hyaluronic acid found 65.2 percent had at least 50 percent pain relief at 12 months, along with a 46.2 percent improvement in the WOMAC function score^[5].

The relief does not last forever. Nerves regenerate, so pain typically returns within 6 to 12 months. The procedure can be repeated, and it has been shown to be safe to repeat in patients who respond well^[3].

Risks are generally low: bruising and tenderness where the needle went in, temporary numbness or weakness, and a brief pain flare. Infection, bleeding, and lasting nerve damage are uncommon but possible^[6].

One thing to know: ablation does not treat the arthritis. It interrupts the pain signal while the joint itself keeps degenerating^[7]. The American College of Rheumatology's 2019 osteoarthritis guideline conditionally recommends radiofrequency ablation for knee osteoarthritis, with the caution that techniques vary across studies and long-term safety data are limited^[8].

What LDRT Does for Knee Arthritis

LDRT is a course of low-dose radiation aimed at the arthritic knee. The typical regimen is six sessions of 0.5 Gy each, a total of 3 Gy, given over about three weeks. For comparison, Cleveland Clinic's Dr. Chirag Shah notes that breast cancer treatment uses 40 to 50 units and prostate cancer 70 to 80, while LDRT for arthritis uses 3^[9].

The newest high-quality data came from a randomized sham-controlled trial of 114 patients with mild-to-moderate knee arthritis, presented at ASTRO 2025. At four months, 70.3 percent of the 3 Gy group were responders, compared with 41.7 percent of the sham group. A lower 0.3 Gy dose did not beat sham. No treatment-related side effects were reported^[10].

The 2026 American Radium Society appropriate-use criteria reviewed 44 studies and reported overall response rates of 60 to 90 percent for pain reduction, mobility, and quality of life, though most of that evidence comes from observational studies^[11]. Cleveland Clinic's early experience put efficacy around 50 to 70 percent, with the honest note that some published studies have been negative^[9].

The skeptical side has real weight too. A 2025 meta-analysis of twelve studies with 1,750 patients found no significant benefit of LDRT over sham for pain or function and concluded it should remain investigational for select refractory cases^[12]. The ACR/Arthritis Foundation 2019 guideline does not include LDRT among its recommended treatments for knee osteoarthritis^[8].

Put plainly: RFA has the deeper trial base for knee osteoarthritis and a place in the guidelines. LDRT is newer, its trials are split, and it sits outside the mainstream guidelines.

Side by Side

• What it changes: ablation interrupts pain signals in the nerves around the knee; LDRT aims at the joint itself. Neither repairs the joint^[7][9].
• The procedure: needle-based, outpatient, under local anesthesia, usually with a diagnostic block first, versus six short radiation sessions over about three weeks with no needles and no anesthesia^[3][10].
• Recovery: brief soreness at the needle sites after ablation; LDRT has essentially no downtime.
• Durability: ablation relief typically lasts 6 to 12 months before nerves regenerate^[3]; LDRT responder data extend to four months in the sham trial, with longer-term results split across studies^[10][12].
• Repeatability: both can be repeated. Ablation is safe to repeat in responders^[3]; a third of joints in one LDRT study received a second course with further pain reduction^[13].
• Side effects: bruising and temporary numbness after ablation; the data suggest the secondary-cancer risk at LDRT doses is very low^[6][9].
• Guideline status: the ACR conditionally recommends ablation for knee osteoarthritis; it does not include LDRT, and a 2025 meta-analysis called LDRT investigational^[8][12].

When Each One Makes More Sense

Ablation usually makes more sense when you have chronic knee arthritis pain that has not responded to conservative care, and surgery is not an option or not wanted. The diagnostic block is a real advantage: it predicts who is likely to benefit before you commit^[3].

LDRT is worth discussing when your arthritis is mild to moderate, you have tried conservative measures, and you prefer something with no needles and no anesthesia. It is also an option to explore before a replacement, but the evidence is more mixed and your insurance may treat it as investigational.

One honest framing: if you want the option with the deeper trial evidence and a guideline recommendation, that is ablation. If you want the gentlest procedure and accept less-certain evidence, that is LDRT. Many patients reasonably ask a pain specialist about ablation and a radiation oncologist about LDRT, then compare.

References:
1. RFA Offers Minimally Invasive Pain Management for Chronic Hip and Knee Pain. Cleveland Clinic ConsultQD (Jianguo Cheng, MD). ConsultQD
2. Nerve Ablation for Knee OA: Where Is Its Place in Treatment? Medscape, 2026. Medscape
3. Kidd VD, et al. Genicular Nerve Radiofrequency Ablation for Painful Knee Arthritis: The Why and the How. JBJS Essential Surgical Techniques. 2019;9(1):e10. Metajournal
4. Davis T, et al. Twelve-month analgesia and rescue, by cooled radiofrequency ablation treatment of osteoarthritic knee pain: results from a prospective, multicenter, randomized, cross-over trial. Regional Anesthesia and Pain Medicine. 2019;44(4):499-508. PubMed
5. Chen AF, et al. Cooled radiofrequency ablation provides extended clinical utility in the management of knee osteoarthritis: 12-month results from a prospective, multi-center, randomized, cross-over trial comparing cooled radiofrequency ablation to a single hyaluronic acid injection. BMC Musculoskeletal Disorders. 2020. PubMed
6. Radiofrequency Ablation of Nerves (Facet Rhizolysis): patient information leaflet. The Dudley Group NHS Foundation Trust. NHS
7. Radiofrequency Ablation. Kentuckiana Pain Specialists (Ajith Nair, MD). Practice page
8. Kolasinski SL, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis and Rheumatology. 2020;72(2):220-233. PubMed
9. Low-Dose Radiation Therapy Reemerging for Osteoarthritis. Cleveland Clinic ConsultQD (Chirag Shah, MD). ConsultQD
10. ASTRO: Low-Dose Radiation Improves Clinical Outcomes in Mild-to-Moderate Knee Osteoarthritis. HealthDay via Drugs.com, October 2025 (reporting Kim BH, et al., ASTRO 2025). Drugs.com
11. Dove A, et al. American Radium Society (ARS) Appropriate Use Criteria (AUC) for Low-Dose Radiotherapy for Treatment of Osteoarthritis. American Journal of Clinical Oncology. Published online May 25, 2026, ahead of print. PubMed
12. Hammadeh BM, et al. Efficacy, safety, and pain management of low-dose radiation therapy in osteoarthritis: a comprehensive systematic review and meta-analysis. Rheumatology International. 2025;45(9):210. PubMed
13. Koneru BN, et al. Low-Dose Radiation Therapy for Osteoarthritis: A Retrospective Single-Institution Analysis of 69 Patients and 168 Joints. International Journal of Radiation Oncology, Biology, Physics. 2025;123(2):352-360. PubMed