Genicular Nerve Block & Radiofrequency Ablation (GNRFA)

Chronic knee pain plagues millions of people, typically due to some form of arthritis. Sometimes over-the-counter or prescribed medications such as Tylenol, ibuprofen, meloxicam, or prednisone help, but often, they prove ineffective.

Injections into the knee joint are a common next step in treatment when oral medications (pills) are not effective. Cortisone or steroid injections are frequently used for these injections with other options such as viscosupplements or hyaluronic acid (referred to as “rooster comb” or “chicken shots”).

Performed by board-certified orthopedic expert Reagan Parr, M.D., the two-part genicular nerve block with radiofrequency ablation, also called a genicular nerve neurotomy, is another alternative treatment to surgery. This therapeutic treatment option involves a diagnostic procedure to temporarily numb or deaden the genicular nerves, which are outside of the knee joint, followed by a procedure weeks later to the same nerves with long-term pain-blocking results.

What Is a Genicular Nerve Block?

Genicular Nerve Block

The knee is innervated, or supplied, by the articular branches of a set of nerves. The sets of nerves are referred to as genicular nerves, and they are responsible for transmitting pain from the knee. A geniculate block knee treatment attempts to stop all or most of the pain by blocking the nerve supply. The procedure involves a doctor injecting a local anesthetic (numbing medicine similar to what is used for getting stitches or dental work) into three to four genicular nerves to interrupt pain signals while using fluoroscopic or ultrasound guidance. Sometimes a steroid is also injected to reduce inflammation.

The knee block procedure is primarily used as a diagnostic treatment or test to determine which nerves are causing the pain and if nerve blocking works for the individual. If the nerve block is successful, pain relief begins within an hour, but the relief is short-lived. The effects of the nerve block last anywhere from eight hours to a maximum of 24 hours. If the first block works, the diagnostic test may need to be performed a second time before the next step is taken. Different insurance plans require a different number of diagnostic blocks.

Generally, if pain is reduced by at least 50 percent with the diagnostic block(s), the doctor knows that blocking certain nerves does work and will proceed with a longer-lasting treatment called a radiofrequency ablation of genicular nerves.

What to Expect During the Diagnostic/Numbing Procedure

During the procedure, the patient lies on a procedure table in a surgery center, and the body, except for the knee being treated, is covered with a sheet. The physician sterilizes the injection sites and numbs them with an anesthetic. Using a fluoroscope (live X-ray machine) as a guidance system, a cannula (needle with a thin tube) is inserted into the correct position near a genicular nerve. While inserted, a local anesthetic is administered to numb, or block, the nerve to stop pain signaling. This procedure is repeated until several (usually three or four) genicular nerves are blocked.

In some cases, people are sedated, so they do not feel any pain from the injection. Once discharged from the ambulatory or same-day surgery center, it is important to resume normal moderate activities that previously caused knee pain. This helps to determine whether the genicular nerve block for knee pain is working. Strenuous activities such as running or hiking, however, should be avoided for a day or two after this procedure.

Radiofrequency Ablation of Genicular Nerves

A longer-term pain relief treatment is the radiofrequency ablation procedure (GNRFA). During this genicular nerve block treatment, patients who responded well to the diagnostic nerve block undergo the ablation procedure, usually done with local anesthetic on an outpatient basis. Once again, fluoroscopic or ultrasound guidance is used.

First, patients will receive medication through an intravenous (IV) line to relax or sedate them. Then a local anesthetic is injected at the injection sites. While your surgeon monitors the live X-ray, a cannula is guided as close as possible to the appropriate nerves, one at a time. Once in place, radiofrequency lesioning (ablation) involves inserting a microelectrode (a very thin wire attached to a machine) into the cannula so that an electrical current produced by a radio wave can heat up the tip of the needle. The hot tip of the needle then cauterizes the nerve transmitting pain signals, so it cannot transmit pain signals to the brain. The process is repeated for each nerve.

The pain relief from the genicular nerve ablation procedure can last from six months to one year, or even longer. It is a low-risk procedure that is done on an outpatient basis.


As an innovative treatment method, genicular radiofrequency ablation offers multiple benefits, including:

  • Safe and effective
  • No use of general anesthesia, reducing side effects
  • Pain relief lasting up to six months or longer
  • The procedure can be repeated as needed
  • Improves joint function
  • Minimizes the need for oral pain medications

Potential Complications

Though both procedures are considered low-risk pain treatments, any medical procedure can lead to complications. Though rare, potential genicular nerve block complications include:

  • Joint inflammation caused by infection
  • Allergic reactions to the anesthetics
  • Severe pain or infection at the needle sites or elsewhere
  • Severe or progressive pain
  • Leg muscle numbness or weakness lasting longer than eight hours
  • Fever

General Pre-Injection Instructions:

Be sure to inform our staff if you have an allergy, particularly to iodine. If you will be receiving sedation, you should NOT eat the morning of the procedure. Sedation is rare for the diagnostic block procedure and common for the ablation procedure. Clear liquids such as black coffee, water, and Gatorade can be consumed up to two hours prior to your arrival to the surgery center. No type of creamer, milk, or juice is allowed the morning of the procedure if sedation is being used. If a patient is an insulin-dependent diabetic and receiving sedation, they may need to change their morning dose of insulin to account for not eating the morning of the procedure. Patients may take their routine medications (i.e., high blood pressure and diabetic medications, such as Glucophage) with sips of clear liquids.

Patients should continue to take pain medications or anti-inflammatory medications on the day of their procedure. If a patient is on Coumadin or another blood thinner, they should notify the staff so an appropriate plan can be made for stopping the medication before the procedure. For any patient receiving sedation, a driver should accompany the patient and be responsible for getting them home.

What Happens After the Procedure?

After the diagnostic nerve block procedure without sedation, the patient is taken to the recovery room. There are no restrictions to food or liquid intake. As mentioned previously, you should resume normal moderate activities that previously caused knee pain. This helps to determine whether the genicular nerve block for knee pain is working. Strenuous activities such as running or hiking, however, should be avoided for a day or two after this procedure. After the GNRFA procedure with sedation, you will have a similar recovery room experience and no food or drink limitations. Due to the effects of the sedation, driving, power tool operation, and signing important documents should not occur within 24 hours of the procedure.

A follow-up appointment will be made a week or two after each procedure to discuss the response to the procedure. It is common for there to be an increase in pain for 2 – 3 days after the GNRFA procedure, thus it does NOT represent an emergency or indicate that anything has gone wrong with the procedure. Patients may return to their normal activities after the initial 24 hours.

Are the Nerve Block & GNRFA Procedures Right for You?

The best candidates for these procedures are those who:

  • Have experienced continued pain after a total or partial knee replacement
  • Want to save knee surgery as a last-resort option
  • Have health issues making knee replacement surgery too risky
  • Experience chronic knee pain due to degenerative joint disease (osteoarthritis)
  • Have a knee injury marked by chronic, painful inflammation
  • Need pain relief before or after knee surgery

To see if the two-part genicular nerve block with radiofrequency ablation procedure is the right option for you, request an appointment online or call one of our four locations: Abingdon, Bristol – Hospital, Bristol Midway, or Johnson City.