Numbing the small nerves that carry pain from the knee. It is a test before longer-lasting treatment.
What is a genicular nerve block?
The genicular nerves carry feeling from the knee joint capsule (the sleeve around the joint). Blocking them tells us whether interrupting those nerves would help. It does so without locking you into anything long-term.
What is a genicular nerve block used for?
- Knee osteoarthritis where injections are no longer helping
- Knee pain that lasts after joint replacement
- Patients who are not candidates for surgery
What to expect
- Ultrasound or fluoroscopic guidance, about 15 minutes.
- You keep a pain diary afterwards. That diary is the result of the test.
- Relief is meant to be short.
- No sedation.
What are the side effects of a genicular nerve block?
A simple outpatient procedure. Temporary numbness over parts of the knee is expected. Bruising at the three injection sites is common. Because sensation is reduced for several hours, care is needed on stairs and uneven ground. Infection is rare with sterile technique.
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How we judge whether it worked
This is a test with one clear purpose. Its job is establishing whether ablation is likely to help before you commit to it.
As with other diagnostic blocks, the pain diary in the hours afterwards is the real result. Strong relief for the duration of the anesthetic is what makes a positive test.
Before and after your procedure
You can usually drive yourself. Expect numbness over parts of the knee for several hours, so take care on stairs and uneven ground. Keep the pain diary. The decision about whether ablation is worth doing depends fully on what you write down in those hours.
What is the procedure for a genicular nerve block?
Several small sensory branches supply the knee capsule. These are usually the superior medial, superior lateral and inferior medial genicular nerves. They run at known points against the bone. Using ultrasound or live X-ray (fluoroscopic) guidance, we place a small volume of local anesthetic at each one. The whole sequence takes about fifteen minutes and needs no sedation. Only the feeling branches are targeted, so the knee does not get weak. The skin over parts of it will feel numb for several hours.
Who it suits, and who it does not
It suits knee osteoarthritis where injections have stopped helping, and pain that lasts after a joint replacement. It also suits patients who are not candidates for surgery or want to put it off. It is less useful when the main problem is mechanical: a knee that locks, gives way or has lost its range. That is because numbing the feeling does not make the knee stable. It is a test, not a treatment, so a patient who will not keep the pain diary gets little from it.
How success is measured
Function is the measure, not a number on a scale. That means how far you walk before symptoms, hours slept, tasks you take back up, and medicine needed. We record those before treatment and compare them after. A procedure that changes a pain score for two weeks, and changes nothing you can do, has not done much. Repeating it is rarely the answer.
Common questions
What happens if it works?
Genicular radiofrequency ablation becomes an option. It usually lasts many months.
Is this the same as a cortisone injection?
No. A cortisone injection puts anti-inflammatory medicine inside the joint. This block numbs the nerves that carry pain from outside it. Its purpose is to predict whether ablation would help.
What if the relief only lasts a few hours?
That is the result we want. Short relief matching the anesthetic is a positive test. It is what makes ablation worth a look.
Will I be able to walk afterwards?
Yes, and most patients drive themselves home. Take care on stairs and uneven ground while the numbness lasts, since the knee will report less than usual.
How long will a genicular nerve block last?
Hours, on purpose. The block uses local anesthetic, so relief lasts only as long as the numbing medicine. The skin over parts of the knee stays numb for several hours. That short window is the test. If it brings strong relief, genicular radiofrequency ablation becomes an option. Ablation usually lasts many months.
Is a genicular nerve block painful?
It is a simple outpatient procedure. A small volume of local anesthetic is placed at three points around the knee under ultrasound or fluoroscopic guidance. The whole thing takes about fifteen minutes. No sedation is used, and most patients drive themselves home. Bruising at the three injection sites is common, and infection is rare with sterile technique.
What are the downsides of a genicular nerve block?
It is a test, not a treatment, so the relief is meant to be short. Temporary numbness over parts of the knee means care on stairs and uneven ground for several hours. It helps little when the main problem is mechanical, such as a knee that locks or gives way. A patient who will not keep the pain diary gets little from it.
Sources
- Kim PY et al. Genicular Nerve Blocks and Radiofrequency Ablation for Knee Osteoarthritis: More Nerves, More Questions. Pain medicine (Malden, Mass.), 2021. PubMed 33538816
- Rambhia M et al. Ultrasound-guided genicular nerve blocks following total knee arthroplasty: a randomized, double-blind, placebo-controlled trial. Regional anesthesia and pain medicine, 2021. PubMed 34261807
- Soetjahjo B et al. The Analgesic Effectiveness of Genicular Nerve-targeted Cooled and Pulsed Radiofrequency Ablation for Osteoarthritis Knee Pain: A Systematic Review and Meta-analysis. Pain physician, 2024. PubMed 39353105
- Cohen SP et al. Emperor’s nakedness exposed: unmasking fairytales for genicular nerve radiofrequency ablation in knee osteoarthritis. Regional anesthesia and pain medicine, 2023. PubMed 36963771
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