What Is Genicular Nerve Block?
The Genicular nerves are a group of small sensory nerves that provide sensation to the knee joint.
Genu, which is Latin for knee, is innervated by both sensory and motor nerves. The knee joint is undisputedly the most complex joint in the body. Not only is it divided into three internal compartments, but the complex interplay between the extensor and flexor muscles and internal stabilizing muscles also allows us to walk, stand, and run utilizing a choreographed sequence of muscle contractions.
Genicular nerve blocks are a way of providing anesthesia, and analgesia to the knee joint without actually entering the capsule or the joint itself.
It’s been well-studied that repeated overuse of steroid injections into any joint, and especially the knee, can lead to Cartilage degeneration, thinning, and worsening of loss of joint space.
The Genicular nerve block is a useful alternative to injections into the knee.
The procedure is often done either under fluoroscopic guidance or ultrasound guidance.
Because the nerves are not seen by the ultrasound, bony landmarks need to be used.
Typically the patient is positioned face-up with a pillow under the affected knee to maintain a slight flexion.
At this point, imaging whether ultrasound or fluoroscopy, is carried out to identify the outer two points along the upper inside portion of the leg bone, or tibia, and the lower portion of the femur or thigh bone. A total of three needles are used in the procedure and can be done either with or without a light sedative.
Once the needles are in position a combination of a long-acting local anesthetic with a touch of steroid is administered. The needles are withdrawn and Band-Aids are applied.
Relief is often immediate with the patient noticing a dramatic improvement in walking ability.
A follow-up evaluation two weeks later determines if the block needs to be repeated.
If there are two successful blocks, meaning that the pain is reduced significantly immediately post-procedure, and however this pain relief is not sustained, these same nerves can be targeted using radiofrequency energy.
The sensory nerves eventually regrow however this can take up to a year during which time the patient has a significant reduction in pain, and is able to exercise and partake in more vigorous physical therapy.
Genicular Nerve Block Procedure
- First, you’ll lie on your back on procedure room table.
- The physician will numb 3-4 areas of skin around your knees with a local anesthetic. Then, guided by an x-ray or ultrasound, physician will:
- Insert 3-4 thin needles into your knees and inject anesthetic
- Usually, the procedure takes less than 15 minutes, and you can go home the same day.
Before and After the Procedure and the Risks
Before the Procedure
You may need to stop taking certain medications several days before the procedure. Please remind the doctor of all prescription and over-the-counter medications you take, including herbal and vitamin supplements. In particular, you should temporarily stop taking for at least 10 days before the procedure date, any medication that can cause unnecessary bleeding: Aspirin, Vitamin E, arthritis medications like Advil, Ibuprofen and blood thinners like Coumadin, Plavix, Trental, etc. The doctor will tell you if and when you need to discontinue the medications.
It is very important to tell the doctor if you have asthma, had an allergic reaction (i.e. hives, itchiness, difficulty breathing, any treatment which required hospitalization) to any local anesthetic agent used in the past, such as novocaine or lidocaine. Tell the doctor if you develop a cold, fever, or flu symptoms before your scheduled appointment.
After the Procedure
Icing for 15 to 20 minutes several times later on the day of the injection is recommended, along with easy range of motion exercises of the joint. You may return immediately to work or regular activities after the injection. You may drive, although some people feel less nervous if they know they have someone along to drive them home. You should continue any physical therapy sessions already scheduled. You may be sore over the treated areas for the first 24 to 48 hours. If any unusual redness or swelling or warmth occurs at the injection site, notify the physician. You may continue taking all of your regular medications. It may take a few days for the corticosteroid medication to start working and you should notice long-term pain relief starting to work by then.
- The risks, although infrequent, include: Allergic reaction to the medications used; Nerve damage; Bruising or infection at the injection site. If you experience persistent pain or numbness in the area of the injection site after the normal healing period (usually 3-5 days), you should call the doctor right away.