Genicular nerve block · St. Louis
Numbing the genicular nerves is not the same as fixing the knee joint, and this block only claims the first one.
A genicular nerve block quiets the sensory nerves that report knee arthritis pain. First it is a diagnostic test. Then it becomes radiofrequency ablation that can hold for months. It lowers the volume; it does not repair the joint.
What does a genicular nerve block treat?
The knee joint capsule gets its feeling from a cluster of small sensory branches. Most often these are the superolateral, superomedial and inferomedial genicular nerves. They carry pain signals up to the spinal cord. They do not move or steady the joint. Their only job is reporting, and in an arthritic knee they report all the time, because worn cartilage, thickened synovium and bone-on-bone contact all create the irritation those nerves exist to detect.
A genicular nerve block numbs those exact branches under fluoroscopic (live X-ray) or ultrasound guidance. If the reporting stops, the pain stops, at least for as long as the local anesthetic lasts. That is useful information on its own. It is also the audition for a longer procedure.
Who is a good candidate for a genicular nerve block?
Three groups make up most of the patients we do this for. First, knee osteoarthritis in someone who is not a surgical candidate. Think heart or metabolic risk, a BMI a surgeon wants lowered first, or a job that cannot absorb the recovery time right now. Second, someone who is a candidate but is choosing to wait, and wants the joint quiet rather than just put up with in the meantime. Third, pain that lasts after a replacement. Imaging shows a sound implant, and the pain source turns out to be the same nerves around the joint that reported on the original knee.
It is a poor fit when the pain is coming from somewhere else — hip and lower-back problems both send pain into the knee often enough that we examine both before reaching for a needle at the joint itself.
How does the genicular block lead to radiofrequency ablation?
STEP ONE — THE DIAGNOSTIC BLOCK
Local anesthetic only, placed at each genicular branch under live imaging. A same-day pain diary tracks how much better, doing what, for how long. A drop of half or more for the expected duration of the anesthetic is a positive test. A block that does little tells us the knee is not the whole story. Then we look elsewhere before doing anything permanent.
STEP TWO — RADIOFREQUENCY ABLATION
If the block works, we heat the same nerves with a radiofrequency probe. That disrupts their signal for months instead of hours. It is never done on the first visit. It is never done on a knee that has not passed the diagnostic step — ablating the wrong nerve wastes a stretch of relief you could have had elsewhere.
POST-ARTHROPLASTY
Same technique, adjusted for hardware. Landmarks shift around a man-made knee. That is why this is done by someone who reads the implant film first, not just the pain diagram.
What it does not do
It does not change the joint. Cartilage that is gone stays gone. Alignment does not correct. The X-ray taken the week after ablation looks exactly like the one before it. What changes is the reporting, not the structure — which is why this fits a patient who has already decided replacement is not happening yet, and does not fit one hoping to never have that talk.
The joint got here through more than mechanics. The terrain around it decides how well a quiet nerve holds. Cartilage is living tissue with its own fuel needs. Insulin resistance and metainflammation break down the cartilage matrix. They slow the low-grade repair that keeps a joint bearable, well before an X-ray calls it severe. Add the load of carrying more weight than the joint was built for. Add a job that keeps you on concrete floors eight or ten hours a day, where getting to a gym is a scheduling problem before it is a motivation problem. Now the social piece is doing as much work as the biology. A nerve block turns down the alarm. It does not touch any of that — see the practice’s approach to metabolic health and pain and movement as part of the plan if the alarm keeps coming back faster than it should.
The evidence, honestly
A 2024 systematic review and meta-analysis of cooled and pulsed genicular ablation found consistent gains in pain and function. Gains were better in studies that required a positive block first. A 2023 placebo-controlled trial of the block alone found real but shorter relief than sham — proof the block works, and a reminder it is not the durable answer ablation is built to be. A 2022 trial of ultrasound-guided block against physical therapy favored the block at short-term follow-up. But the comparison group was rarely people who had already used up therapy, and that is most of who walks into this office.
What the trials mostly leave out: uncontrolled diabetes, active joint infection, significant vascular disease in the limb, or the deconditioning (lost strength and fitness) of someone who has avoided using the knee for years. That does not mean the procedure fails there. It means the published numbers were not measured on it. We say so rather than borrow a trial’s confidence for a patient it did not enroll. Our position: a positive block is the gate, not the guess. When relief fades early, the honest reason is usually the terrain the joint sits in, not the technique.
What happens during a genicular nerve block?
- Baseline pain and function recorded, including which activities the knee is currently blocking you from.
- Positioned on your back, knee slightly bent, skin cleaned and numbed over each target point.
- Needles advanced under live imaging to the genicular landmarks, checked against bone before anything is injected.
- Medication delivered (block) or the nerve heated for a set interval (ablation), then the needles removed.
- No sedation. Observation, then most patients drive themselves home. Keep a same-day diary for a diagnostic block. Expect several days before the ablation effect can be judged.
What are the risks of genicular nerve block and ablation?
Bruising and soreness at the injection sites are common and short-lived. Infection is rare with sterile technique. A small number of patients get a patch of numb skin near the site, usually temporary. Ablation carries a small added risk of a burning feeling in the days after. We tell you to expect it rather than call to report it, unless it is severe. Nerve tissue grows back, which is why relief is not permanent — and why repeating it later does not carry the stacked risk that repeated steroid exposure would.
Common questions
Will this let me avoid a knee replacement entirely?
For some, yes, for years. For others it is a bridge to surgery scheduled on their own timeline rather than the joint’s. Either way the decision belongs to you and your surgeon — see what to expect for how we coordinate that referral.
How long does the relief last?
The diagnostic block lasts hours. The ablation typically holds for six months to a year, sometimes longer, and can be repeated because the nerve regrows and can be treated again. Read more on what it means when relief stops holding.
Can I have this if I already had a knee replacement?
The genicular nerves can still be treated after a knee replacement, as long as the implant has been checked and is not loose or infected. Lasting pain after a technically sound replacement is more common than patients are told. As discussed on knee pain, the same nerves are often the source.
Is this the same as an injection into the knee joint itself?
No. Steroid, hyaluronic acid and orthobiologic injections go into the joint space. A genicular block or ablation targets the nerves outside it. See image-guided joint injections for the in-joint options and how we choose between the two.
Why do I need the diagnostic block first?
Because knee pain is not always knee pain, and treating the wrong source wastes the window without helping. The block confirms the target before the longer procedure — the same logic behind a medial branch block before spinal radiofrequency ablation.
How painful is a genicular nerve block?
We numb the skin over each target point first, then guide the needles under live imaging and confirm them against bone before anything is injected. Afterward, bruising and soreness at the injection sites are common and short-lived. If you go on to ablation, a burning feeling for a few days afterward is expected, and you only need to call us if it is severe.
How often can you have a genicular nerve block or ablation?
The ablation usually holds six months to a year, sometimes longer. Because the nerve grows back, it can be treated again when the relief fades. Repeating it does not carry the build-up risk that repeated steroid injections do. If relief keeps fading faster than it should, we look at the terrain around the joint, not just the needle.
What happens if a genicular nerve block doesn’t work?
A block that does little is a useful answer. It tells us the knee is not the whole story. Hip and lower-back problems often send pain into the knee, so we look there before doing anything permanent. We never move on to ablation for a knee that did not pass the diagnostic block. You will hear directly where to look instead.
Related reading
- Orthobiologics and PRP injections in St. Louis
- Knee pain
- Image-guided joint injections
- When injections stop working
- Metabolic health and pain
- Hip pain
- Bone-on-bone knee
We will tell you what the block found before we schedule anything else
The diagnostic step exists so nobody guesses. If your knee is not the source of your pain, you will hear that directly, and we will help you find where to look instead.
4479 Woodson Rd, Suite 401
St. Louis, MO 63134
Next to St. Louis Lambert International Airport, off I-70 at Woodson Road.
Sources
- 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. Korean Journal of Pain, 2024. PubMed 39353105
- Shanahan EM et al. Genicular Nerve Block for Pain Management in Patients With Knee Osteoarthritis: A Randomized Placebo-Controlled Trial. JAMA Network Open, 2023. PubMed 36369781
- Güler T et al. Ultrasound-guided genicular nerve block versus physical therapy for chronic knee osteoarthritis: a prospective randomised study. Clinical Rheumatology, 2022. PubMed 35165769
- Conger A et al. Genicular Nerve Radiofrequency Ablation for the Treatment of Painful Knee Osteoarthritis: Current Evidence and Future Directions. Pain Medicine, 2021. PubMed 34308957