Genicular nerve ablation

Several small sensory nerves wrap around the knee, called the genicular nerves. They carry pain signals from the knee joint to the brain, but they do not control the muscles. When knee arthritis (osteoarthritis) causes constant pain, these nerves keep sending that signal.

In genicular nerve ablation, also called genicular radiofrequency ablation (RFA), the doctor places thin needles next to these nerves using X-ray or ultrasound. A probe at the tip heats the nerve with radio waves, usually to about 80 to 90°C for 1 to 3 minutes. This stops the nerve from sending pain signals for many months. Your knee still works the same way, and your leg muscles keep their strength.

The ablation treats the pain signal, not the arthritis itself. The nerves slowly grow back, so the pain may return after months to a couple of years. The treatment can be repeated.

On the X-ray image, the needle tips rest against specific points on the thigh bone and shin bone just above and below the joint, where the genicular nerves run along the bone.

Genicular nerve ablation fits between injections and knee replacement. Another option, genicular artery embolization (GAE), treats the same kind of knee pain in a different way: it blocks tiny abnormal blood vessels that feed inflammation in the knee lining, through a pinhole in an artery.

Steroid injections often help for a few weeks to a few months. Hyaluronic acid (gel) injections help some people. Knee replacement is a proven, lasting fix for severe arthritis, and choosing ablation does not stop you from having surgery later.

Before the ablation, you have a genicular nerve block. It uses the same needle positions, but only numbing medicine, and takes about 15 minutes. If your knee pain drops by about half or more for the few hours the medicine lasts, the ablation is likely to help. Try the activities that usually hurt, such as walking or stairs, and write down your pain score every hour.

Some practices and insurance plans use one test block, others two. Learn more about blocks on our nerve blocks page.

1. 1
   Positioning

   You lie on your back with a pillow under the knee. A grounding pad is placed on your thigh or back. The skin is cleaned and numbed.

2. 2
   Placing and testing the needles

   Using X-ray or ultrasound, the doctor places 3 to 5 thin needles next to the nerves. A mild electrical test confirms each needle is near a sensory nerve and away from nerves that move your leg.

3. 3
   Treating the nerves

   More numbing medicine goes through each needle. The tips are then heated for about 1 to 3 minutes each. You may feel warmth or pressure.

4. 4
   Finishing

   The needles are removed and small bandages applied. You rest for about 30 minutes, then walk out.

1. First day
   The knee may feel numb from the medicine. Walk as you feel able. Ice for 15 to 20 minutes at a time helps soreness. No driving if you had sedation.
2. Days 2 to 7
   Most people are back to normal activity. Some soreness or a sunburn-like feeling around the knee is common and fades.
3. 2 to 4 weeks
   The full effect usually appears. Pain often gets better gradually rather than all at once.
4. 6 to 12 months or longer
   Relief may slowly fade as the nerves regrow. If the first treatment helped, it can usually be repeated.

In published studies, most people who had a good test block have meaningful pain relief at 6 months, and many still do at 1 year. Walking, stairs and sleep often improve. Results vary, and some people get little benefit.

Many of my patients with knee arthritis are caught between injections that no longer last and a knee replacement they are not ready for. I look at the X-rays and ask where exactly it hurts and what they want to get back to. I explain both the nerve ablation and the embolization, because they work in different ways and one may fit a person better than the other.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos

Genicular nerve ablation is considered low risk. Side effects are usually mild and short-lived.