Anesthesiology | Interventional Pain Medicine
Assistant Professor — University of Toronto
Interventional Pain Physician — Afiya Spine & Pain Institute
Staff Anesthesiologist — Scarborough Health Network
Genicular nerve blocks are injections used to test whether pain from the knee is being carried by the small sensory nerves around the knee joint.
These nerves are called genicular nerves. They do not control the main strength or movement of the leg. They carry pain signals from the knee region toward the brain.
The block uses local anesthetic to temporarily numb selected genicular nerves. If your usual knee pain improves during the numbing window, that suggests you may be a candidate for knee radiofrequency ablation.
An intra-articular knee injection may be performed at the same appointment to provide temporary pain relief while the response to the nerve blocks is assessed and, if appropriate, while knee radiofrequency ablation is being scheduled.
The joint injection may use corticosteroid medication or Durolane. Durolane is a hyaluronic acid injection. It is sometimes described as a gel or lubricant injection.
Steroid injections are usually cheaper and may work faster, often over days. The benefit is usually temporary and may last weeks to a few months.
Durolane is considerably more expensive. It may take longer to work, and the evidence is mixed. Some patients feel meaningful relief for several months, while others notice little benefit. It is not usually a quick rescue treatment.
This procedure is most commonly considered for chronic knee pain from osteoarthritis when pain remains significant despite medication, physiotherapy, exercise, bracing, weight management, or previous injections.
The genicular nerve block portion is a test. The goal is not long-term relief from the block itself, but to determine whether the genicular nerves are carrying a meaningful part of your pain.
If the blocks provide meaningful temporary relief, we may discuss knee radiofrequency ablation, which is a longer-lasting treatment aimed at the same nerves.
Tell us if you have a knee replacement booked within the next 6 months. We generally do not want to inject steroid into the knee joint if this could delay your surgery.
Tell us if you already have a knee replacement, have had recent knee surgery, have an active infection, are taking antibiotics, or have had a recent major change in your health.
You usually do not need to fast for this procedure unless you are specifically told otherwise.
The injections are quick, but the full visit includes check-in, assessment, preparation, and recovery.
Most patients should expect the full appointment to take approximately 60 to 90 minutes, although this can vary depending on clinic flow that day.
The exact targets and medication plan depend on your pain pattern, examination, X-rays or other imaging, previous treatments, and whether knee replacement surgery is being considered.
Most patients describe:
Local anesthetic is used to reduce discomfort. The procedure is usually brief.
The numbing medication from the genicular nerve blocks usually lasts for several hours. This is the most important part of the test.
During this time, pay attention to whether your usual knee pain is better when you do the activities that normally bring it on. This may include walking, stairs, standing from a chair, standing for longer periods, or other usual painful movements.
Do not simply go home and rest for the full numbing period. The test is most useful when you gently test your usual painful activities in a safe and controlled way.
You may walk and do normal light activity after the procedure. Avoid unusually strenuous activity for the rest of the day.
Log your pain level out of 10 every hour for 6 hours after the injection.
Also write down:
Bring your pain log to your follow-up appointment. Your pain log helps determine whether knee radiofrequency ablation is appropriate.
The genicular nerve block is expected to work only during the numbing window. If the knee joint injection included steroid, relief may take a few days. If it included Durolane, relief may take several weeks.
It is common to have temporary soreness or a pain flare before the benefit from the joint injection becomes clear.
The next step depends on how much relief you had during the numbing window.
If your usual knee pain clearly improves for the expected duration of the numbing medication, this supports the genicular nerves as a meaningful pain pathway. In that case, we may discuss knee radiofrequency ablation.
If your pain does not improve, that is still useful information. It suggests that genicular nerve radiofrequency ablation may be less likely to help, and we may consider other options.
Some patients have more than one source of knee pain. Genicular nerve blocks may help identify pain carried by the genicular nerves, but they may not explain all of your symptoms.
Keep the injection sites dry for 24 hours. Remove bandages after 24 hours.
Genicular nerve blocks and knee joint injections are generally low-risk procedures when performed with image guidance and sterile technique.
The most common issues are mild soreness, bruising, temporary lightheadedness, temporary increase in pain, temporary knee swelling, or temporary irritation after the injection.
Uncommon risks include bleeding, infection, allergic reaction, medication entering a blood vessel, or temporary numbness from local anesthetic spreading to nearby nerves.
Steroid injection into the knee before knee replacement surgery may delay surgery because of infection-risk concerns. Tell us if you have a knee replacement booked within the next 6 months.
Seek medical attention if you develop fever, worsening redness or swelling at the injection site, drainage from the injection site, severe worsening pain, or a hot swollen knee that does not settle.
The procedure itself, including the clinic visit and use of X-ray guidance, is covered by OHIP.
OHIP does not cover the cost of medications used or prescribed, such as local anesthetic, steroid medication, Durolane, contrast dye, or other medications. These costs may be covered by private insurance.
Steroid medication is usually much less expensive than Durolane. Durolane is considerably more expensive, and the clinic will confirm the current cost before proceeding.
Unless you are told otherwise, you may usually take your regular medications. Blood thinners require separate review.
Tell us before the procedure if you take blood thinners or antiplatelet medications. Do not stop them on your own. We will give you specific instructions based on the medication and your medical history.
Tell us before the procedure if you have ever had an allergy or serious reaction to contrast dye, local anesthetic, steroid medication, Durolane, hyaluronic acid products, or antiseptic skin-cleaning solution.
Tell us if you have diabetes, an active infection, are taking antibiotics, are pregnant or may be pregnant, have a knee replacement booked within the next 6 months, or have had a recent major change in your health.
Afiya Spine & Pain Institute
301 - 15 Wellesley St W, Toronto, ON M4Y 1G1
Phone: 416-413-7999 | E-Fax: 416-641-4520
For questions or concerns after your procedure, contact the clinic.