Facet Joint Injection
(Medial Branch Block; Zygapophysial Joint Injection; Z-Joint Injection)
The spine is made up of bones called vertebrae. Each vertebra has two pairs of facet joints. One pair points up and connects with the vertebrae above. The second pair points down and connects with the vertebrae below.
These joints have cartilage, ligaments, and a surrounding sac of fluid to allow smooth movement. Injury to any of these structures may cause swelling and pain. The swelling may also put pressure on nerves as they exit the spinal cord. This may result in local pain or pain that shoots down the limbs.
A facet joint injection is a shot directly into the joint. The shot will have a small amount of a numbing medication (anesthetic) and/or medication to reduce swelling.
In some cases, the injection is done just beside the joint at a tiny nerve branch that supplies the joint. This is called a medial branch block. This is often done as a diagnostic test with just a numbing medication to see if the targeted area is the source of pain.
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Reasons for Procedure
It is not always clear what causes back or neck pain. It may be caused by problems of the joint, nerves, or other structure, such as muscles or ligaments. A facet joint injection of a numbing medication may be used to confirm or disprove the joint as the cause of pain.
If the facet joint is the cause of pain, injections may be used to deliver steroid medication to try to help control pain and inflammation.
Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:
- Tenderness, bruising, or bleeding at the injection site
- Worsening of pain
- Allergic reaction to the medication used
- Nerve injury
- Muscle weakness
Smoking may increase your risk of complications.
Your doctor may not want to do this injection if you:
- Have had pain for a short time (less than 6 weeks)
- Have had success with conservative treatment
- Have not tried other conservative treatment
- Have allergies to the local anesthetic, x-ray contrast, or medications being used
- Have a bleeding disorder or take blood thinning medication
- Have pain that is due to an infection or malignancy
- Uncontrolled high blood pressure or diabetes
- Unstable angina or heart failure
What to Expect
Prior to Procedure
Your doctor may begin with conservative treatment such as rest, medication, physical therapy, and exercise.
Before the procedure you may need:
- A physical exam
- Imaging tests to evaluate the spinal structures with x-rays or an MRI scan
- To discuss allergies that you may have to the anesthetic, pain medication, or latex
In addition, talk to your doctor about your medications. You may have to stop taking some medications up to one week or more before the procedure.
- Your doctor may ask you to avoid food or drink a few hours before the procedure.
- You will need someone to drive you home after the procedure.
You will be awake during the procedure. A local anesthetic will be used to numb the skin before the injection. Your doctor may also give you additional medication to help you relax.
Description of Procedure
You may have devices attached to help monitor your blood pressure, heart, and oxygen levels. You will be asked to lie on your stomach or side on an x-ray table. The skin around the injection site will be cleansed with an antiseptic. A local anesthetic may be given to numb the area.
The doctor may inject a contrast dye. This dye will help to highlight the joint in an x-ray and help ensure the correct placement of the injection. This type of x-ray is called a fluoroscopy. The doctor will place the needle into or around the joint and inject the anesthetic medication. You will be asked about your pain relief during the procedure.
If you have pain relief after the injection, this may mean the problem is due to the facet joint. A second injection with a steroid medication may be done to reduce inflammation and swelling.
If you do not have pain relief after the first injection, your doctor may:
- Try another facet joint
- Inject more medication
- Try an alternative spine injection, such as a medial branch block
Immediately After Procedure
You will stay at the clinic for up to 30 minutes after the injection.
How Long Will It Take?
The injection only takes a few minutes. The entire visit may be 30-60 minutes. The length of time will depend on the number of injections needed and how you recover.
How Much Will It Hurt?
This is a deep injection so you may have some discomfort. Ask your doctor about medication to help with the pain after the procedure.
You may have complete or partial pain relief.
At the Care Center
Your doctor will assess your level of pain relief. You may be asked to do movements that had been causing pain before. This can help to see if you feel better after the injection.
You might feel some numbness, weakness, or tingling for a few hours after the injection. You may need to avoid certain activities. You can slowly increase your activity as tolerated or by your doctor's instructions. You can apply ice to the affected area to relieve swelling and discomfort.
Pain can be managed with medications. It may take time for a steroid medication to work.
Proper care of the insertion site can help prevent infection. If you have diabetes, monitor your blood sugar levels more carefully a few weeks after an injection. The medication that was injected may cause elevated blood sugar levels.
Call Your Doctor
Call your doctor if any of these occur:
- Redness, swelling, increasing pain, bleeding, or discharge from the injection site
- Nausea or vomiting
- Severe pain or headache
- Fever or chills
- Loss of bladder or bowel control
- Progressive weakness or numbness
If you think you have an emergency, call for emergency medical services right away.
American Chronic Pain Association
Ortho Info—American Academy of Orthopaedic Surgeons
Bykowski J, Wong W. Role of facet joints in spine pain and image-guided treatment: a review. AJNR Am J Neuroradiol. 2012;33(8):1419-26.
Facet joint injections. Bupa website. Available at: https://www.bupa.co.uk/health-information/directory/f/facet-joint-injections. Accessed December 19, 2017.
Lumbar zygapophysial (facet) joint injections. Know Your Back—North American Spine Society website. Available at: https://www.knowyourback.org/KnowYourBack/Treatments/InjectionTreatmentsforSpinalPain/LumbarZygapophysialJointInjections. Accessed December 19, 2017.
Spinal injections. American Academy of Orthopedic Surgeons Ortho Info website. Available at: https://orthoinfo.org/en/treatment/spinal-injections. Updated December 2013. Accessed December 19, 2017.
Last reviewed November 2018 by EBSCO Medical Review Board Michael Woods, MD, FAAP Last Updated: 12/20/2014