Zygapophysial joints (also known as facet joints or z-joints) are located on the back (posterior) of the spine on each side where two adjacent vertebrae meet. The facet joints provide stability and permit the spine to bend and twist. The joint contains cartilage between bones and is surrounded by a sac-like capsule that is filled with synovial fluid (lubricating liquid that reduces the friction between bony surfaces with movement).
There are basically two reasons for having a facet joint injection:
Diagnosis (to determine the source of pain).
Therapy (to treat an abnormality that has been detected).
Most back pain will improve within a few weeks with conservative medical care including options like relative rest, nonsteroidal anti-inflammatory medications, physical therapy, and exercises. If you suffer from back pain for more than six weeks despite appropriate medical care, your healthcare provider may order diagnostic tests like x-ray, MRI (magnetic resonance imaging), or CT (computed tomography) scans to evaluate the structure of the spine. A problem (such as inflammation, irritation, swelling, or arthritis) in the facet joints may contribute to low back pain and may be visualized on diagnostic imaging. However, normal appearing joints on diagnostic imaging do not completely rule out facet joints as source of pain.
To determine if the facet joint is truly the source of pain, an injection (sometimes called “block”) may be performed. If the low back pain pain is reduced or relieved after an anesthetic or numbing medicine is injected into the facet joint or onto the small nerve that supplies the joint, your healthcare provider may feel confident that the facet joint is the source of your pain. If the facet joint is felt to be the source of your pain, a corticosteroid or steroid (strong anti-inflammatory) may be injected in addition to the numbing medicine to provide longer term relief of the pain.
Facet injections may be intraarticular (into the joint) or medial branch blocks (where the medication is injected onto the nerve). These procedures are performed while you are awake using local anesthetic (numbing) much like when you see the dentist. If needed, some medications may be given to help you feel more relaxed or comfortable for the procedure. You will be positioned lying on your stomach and you will be hooked to monitors to watch blood pressure, heart rate, and oxygen level. Your physician or an assistant will clean and sterilize the area. The injection is performed with the use of x-ray guidance called fluoroscopy. Before the procedure your physician will explain the risks, benefits, alternatives, and complications and obtain your consent to perform the procedure. The procedure takes approximately 30-60 minutes.
You should let your healthcare provider know if you have a bleeding disorder or if you are using medications or herbal treatments that may affect bleeding. Examples include aspirin, warfarin, clopidogrel, ticlopidine, heparin, enoxaparin, and anti-inflammatory medications (such as ibuprofen, naproxen, nabumetone, diclofenac, etodolac, indomethacin, ketorolac, meloxicam, piroxicam, ketoprofen, or oxaprozin). NSAIDs may be stopped 3-7 days prior to procedure. Other medications should be discussed with your primary physician or cardiologist who will determine if and how to stop medication prior to procedure.
Please let your healthcare provider know if you had any recent events (like hospitalization, fever, antibiotic treatment, or any illnesses) within 4 weeks prior to the procedure. You should be healthy the day of your procedure. If you have diabetes, you should monitor your sugars closely on the day of the procedure and for the first 2-3 weeks after the procedure. You may experience transient elevation in the sugar numbers.
You will usually not be able to eat or drink for several hours before the procedure. You will likely need to have someone drive you home from the procedure.
You will typically be observed for 15-30 minutes after procedure. You will be allowed to resume normal medications and eat after the procedure. You will be able to walk after procedure but should avoid strenuous activities for the rest of the day. Although uncommon, some patients may experience transient leg weakness or numbness and tingling. Some patients may notice muscle spasms or transient increase in pain. You may have a small bandage after your procedure and may apply ice to the area on 20 minutes and off 30 minutes. You should not immerse yourself in water (soak in tub or pool) for first 24 hours but may shower.
A diagnostic injection will likely contain an anesthetic which will wear off in a period of hours to days. A therapeutic injection will contain both anesthetic and steroid. You may have a period of time when the anesthetic wears off but the steroid has not started to work yet. The steroid may take 48-72 hours up to 1-2 weeks to begin relieving pain. You will likely keep a pain diary that will be returned at the follow-up visit after the procedure.
Repeat injections may be considered depending on pain relief provided. Otherwise, facet injections may be precursors to other therapeutic measures. These can be discussed with your healthcare provider.
Radiographic Assessment of Spinal Disorders