Facet joint block for low back pain: what it is and when it's used

Name: Facet joint block: the treatment many patients with low back pain have never heard of
Creator: Dr. Mauricio Casarsa
Published: 2026-05-13

Low back pain has many possible causes, and one of the most common — and most underdiagnosed — is facet joint syndrome. The facet joints are small joints on each side of the spine that allow movement between the vertebrae. With time, use or minor injuries, these joints can degenerate, become inflamed and turn into a source of chronic pain.

In my office I see two extremes when it comes to facet joint blocks: patients who ask for one as if it were the magic fix for any kind of low back pain, and patients who arrive frightened because they've heard it's "an injection in the spine." Neither mindset strikes me as helpful. The facet joint block is an excellent tool when the pain genuinely comes from the facet joints, and a fairly poor one when the pain comes from somewhere else. Before talking about the procedure itself, what matters is working out whether the clinical picture fits.

The interesting part is that facet joint pain has distinctive clinical features — and a treatment that many patients have never heard of simply because it was never offered to them: the image-guided facet joint block.

How facet joint pain is recognized

The typical picture of lumbar facet joint syndrome includes:

Low back pain, usually worse on one side than the other.
Pain that worsens with prolonged standing or walking, especially when arching the back backward.
Worsening when getting up from a chair after sitting for a long time.
Relief when sitting down or leaning forward (the opposite of the posture that hurts).
It may radiate to the buttock or the back of the thigh, but it typically does not go past the knee (unlike true sciatica).
More common after age 40-50.

It's a very recognizable picture once you look for it. Yet patients have often been through several doctors without anyone raising this possibility.

One important technical nuance: MRI shows degenerative facet changes in a huge proportion of adults who have never had low back pain. Seeing facet joint osteoarthritis on a scan does not mean the pain is coming from there. That's why the facet joint block is approached in two stages: first as a diagnostic block, with local anesthetic, to confirm that this particular pain responds to that joint; and only afterward, if the response is clear, do we consider longer-lasting treatment or radiofrequency ablation. Skipping the diagnostic step is one of the most common reasons treatments fail.

How the diagnosis is confirmed

The history and physical exam point the way, but the definitive diagnosis is made with a diagnostic block: a local anesthetic is injected around the small nerves (the medial branches) that carry sensation from the facet joints. If the patient's pain disappears or improves significantly over the following hours, that confirms these joints are the source of the pain.

Imaging (MRI, X-rays) may show facet joint osteoarthritis, but it isn't decisive: some people have marked degenerative changes on imaging and no pain, and vice versa. The therapeutic trial of a diagnostic block is what confirms where the problem originates.

How a facet joint block is performed

The procedure is done on an outpatient basis, under fluoroscopy (real-time X-ray) or ultrasound guidance:

The patient lies face down on the table.
The skin is prepped with antiseptic and numbed with local anesthetic.
Under image guidance, the facet joint or the medial branch is precisely located.
Local anesthetic is injected, with or without a corticosteroid depending on the case.
The same procedure is repeated at the affected levels (typically 2 or 3 levels on each side).
Recovery takes 15-30 minutes, then the patient goes home.

Total time: 20-40 minutes.

What to expect from the results

There are two separate questions:

The diagnostic block

It confirms or rules out the facet joints as the origin of the pain. The immediate relief (from the local anesthetic) usually lasts hours, and that alone is valuable clinical information.

The therapeutic block (with corticosteroids)

Once the facet origin is confirmed, a therapeutic block with corticosteroids can provide sustained relief for weeks or months. The response varies: some patients report lasting improvement after one or two blocks; others need periodic repeat injections.

Radiofrequency ablation of the medial branches

When therapeutic blocks help but the effect is relatively short-lived, the next step is radiofrequency ablation of the medial branches (also known as rhizotomy or rhizolysis): a more sophisticated technique that offers prolonged relief (6 to 12 months or longer in many cases). It is one of the procedures with the strongest evidence in interventional pain medicine.

Why this treatment is so little known

There are several reasons:

Facet joint syndrome is relatively underdiagnosed outside of specialist care.
The procedures require image guidance and specific training that not every physician has.
Many patients assume that "all low back pain comes from the disc," when in fact the causes are varied.
The diagnosis calls for a focused clinical evaluation that takes time and dedication.

My threshold for recommending a facet joint block is fairly demanding: axial low back pain, worse with extension and rotation, without a dominant radicular component, and no longer responding to several weeks of well-conducted conservative care. When the diagnostic block relieves the pain significantly, then it makes sense to consider medial branch radiofrequency ablation, which is what delivers sustained relief. If the diagnostic block doesn't work, I don't push on: I'd rather rethink where the pain is coming from than repeat a procedure that has already shown it isn't the answer.

When it's worth considering

If you have low back pain with the features described above — especially if it worsens when you arch your back, improves when you bend forward, and hasn't responded to standard treatment — it's worth having a dedicated visit to evaluate a possible facet joint origin. A thorough evaluation, a focused physical exam and, when appropriate, a diagnostic block can significantly change your treatment outlook.

The good news is that once a facet origin is confirmed, treatment follows a stepwise, effective path that can provide lasting relief through outpatient procedures. No surgery and no long-term medication required.

When a patient comes back months after a well-indicated radiofrequency ablation and tells me they're back to taking walks, sleeping better and taking fewer painkillers, it's almost always because we went through the full process: a clear clinical identification, a positive diagnostic block and targeted treatment. The facet joint block is neither a miracle nor a fashionable overdiagnosis; it's a precise technique that works when applied to the right patient. My job is precisely that upfront filter — it's what prevents unnecessary procedures and, above all, the frustration of treatments that never address the real source of the pain.

Low back pain that just won't go away?

It's worth finding out whether the facet joints are the cause. If they are, a facet joint block may be the solution.

💬 Could a facet joint block help my case?

Lumbar facet joint block — frequently asked questions

What exactly is a facet joint block?

It is an image-guided injection (fluoroscopy or ultrasound) of a local anesthetic and, in most cases, a corticosteroid into or near the facet joints: small joints on each side of the spine that wear down with age and are a very common cause of mechanical low back pain.

Is a facet joint block painful?

It is performed under local anesthesia, and what patients most often feel is pressure rather than sharp pain. The procedure takes 15-20 minutes and is done on an outpatient basis. Over the first 24-48 hours there may be some local soreness at the injection site, which resolves on its own.

How long does the effect of a facet joint block last?

It varies. Some patients get lasting relief for months or years. Others respond well for a few weeks. When the response is good but short-lived, the usual next step is radiofrequency ablation of the medial branches, a technique derived from the facet joint block that typically provides 6 to 12 months of relief.

When is a facet joint block indicated?

In mechanical low back pain (pain that worsens when standing, arching the back or getting up from a chair) without significant pain radiating down the leg, especially after age 50, when imaging shows facet joint osteoarthritis and the pain has not improved with standard conservative treatment.

References and further reading

Cohen SP, Bhatia A, Buvanendran A, et al. Consensus Practice Guidelines on Interventions for Lumbar Facet Joint Pain from a Multispecialty, International Working Group. Reg Anesth Pain Med. 2020;45(6):424-467.
Manchikanti L, Kaye AD, Soin A, et al. Comprehensive Evidence-Based Guidelines for Facet Joint Interventions in the Management of Chronic Spinal Pain. Pain Physician. 2020;23(3S):S1-S127.
Manchikanti L, Hirsch JA, Falco FJ, Boswell MV. Management of lumbar zygapophysial (facet) joint pain. World J Orthop. 2016;7(5):315-337.
van Kleef M, Vanelderen P, Cohen SP, Lataster A, Van Zundert J, Mekhail N. Pain Originating from the Lumbar Facet Joints. Pain Pract. 2010;10(5):459-469.

Dr. Mauricio Casarsa

Anesthesiologist, specialist in Pain Medicine and Interventional Pain Management. Postgraduate training at UBA (Fundación Dolor) and UNLP (CAIDBA). Staff physician at Hospital Alemán, Buenos Aires.

MN 137756 · San Isidro · Villa Urquiza