Facet joints are the small paired joints at the back of the spine. They link each bone of the spine to the one above and below. When one starts causing pain, no scan or exam test can prove it. The only way to know is to numb the nerves to the joint and see if the pain goes away. That is why a diagnostic block and a therapeutic injection are different. It is also why a rhizotomy is only worth a look after a positive block.
What a facet joint is
Each spine bone connects to its neighbors in three places. The disc is in front, and a pair of facet joints sit behind. The facet joints are true synovial joints, like a knuckle. They have cartilage, a capsule and a slick lining. Each is about the size of a thumbnail. Their job is mechanical. They guide and limit motion. They take the load when you bend back or twist, while the disc takes the squeeze. Like any such joint, they wear down. Because they have nerves, they can hurt.
That nerve supply drives the whole testing plan. Each facet joint gets its feeling from two medial branches. These are small nerves that come off the spine at the joint’s level and the level above. Two nerves, one joint. No facet joint has a nerve of its own. So a block or ablation aimed at one joint must hit two nerves. That is also why test blocks are done at two levels to check one joint.1
The medial branch does more than carry feeling. Along with the fibers that carry pain from the joint, it also feeds the multifidus muscle. It feeds the small muscle and ligament between the spine bones, too. And it feeds the periosteum, the thin lining of the bony arch.2 That matters later. Cutting off the nerve also cuts off part of that deep muscle.
How facet-mediated pain presents
Facet pain is axial, meaning it stays near the spine. It sits in the neck or low back near the middle. It spreads in a vague, broad pattern, not a sharp line down a nerve. From the neck it goes into the shoulder blade and upper arm. From the low back it goes into the buttock and back of the thigh. It usually stops above the knee or elbow. It causes no true numbness, weakness or reflex loss. The pattern is mechanical. It gets worse when you bend back or twist, and better when you lean forward. No single sign proves it.
One retrospective review looked back at 500 patients in a row with chronic spine pain. All were tested with controlled comparative anesthetic blocks (paired numbing blocks). Of those, 438 qualified. Facet joints caused the pain in 39% of neck cases, 34% of mid-back cases and 27% of low back cases.1 That came from one specialty clinic, so the numbers run higher than a family doctor would see. Still, facet pain is common enough to look for. It is far from the cause in everyone.
Why imaging cannot make the diagnosis
Wear and tear in the facets on CT or MRI gets common with age. It does a poor job of showing which joint, if any, is causing pain. A panel of experts from many fields wrote a guideline on low back facet treatments. They found no history or exam finding that reliably predicts who will respond to facet blocks. They also found no link between bad-looking facets on MRI and how well nerve ablation worked.2 The neck guideline reached the same answer. Scans are not enough to diagnose facet pain. They are still useful to plan the procedure.3 This is not a flaw in the scanners. Scans show structure. Pain comes from nerve signals. A joint can look terrible and be silent.
Diagnostic block versus therapeutic injection
People often use these two terms as if they mean the same thing, even on clinic websites. They are not the same.
The medial branch block
A medial branch block puts a small amount of numbing medicine on the two medial branches feeding the suspect joint. The doctor guides the needle with live X-ray, called fluoroscopy. The block is not meant to treat anything. It asks a yes-or-no question. With those nerves quiet, does the usual pain go away? And does it come back as the numbing wears off?
The amount matters. Too much numbing medicine spreads to other spots and gives a false positive. Sedation matters too. A sedated patient may report relief from the sedative, not the block. The expert guideline looked at both questions. It also found that medial branch blocks predict ablation success better than intra-articular injections (shots into the joint).2
The intra-articular facet injection
An intra-articular injection puts steroid and numbing medicine inside the joint capsule. It is meant both to test and to treat. It is what most people mean by “facet injection.” As a treatment, its record is weak. A 2025 systematic review looked at fluoroscopically guided (live X-ray) steroid shots into low back facet joints. Success rates ran from 13% to 74%. The review graded the evidence very low quality. Observational studies (which just watch patients) suggest benefit. Sham-controlled trials (against a fake shot) have not shown it works.4 That wide spread comes from how patients were picked, not from the drug.
Why one positive block is often not enough
One positive block is not reliable. In the study above, one block gave a false positive 45% of the time in the neck, 42% in the mid-back and 45% in the low back.1 About two in five people who get relief from one block do not have facet pain. Placebo, medicine soaking into the blood and numbing spread all play a part.
The fix is a controlled comparative block (a paired block). Repeat it on another day with a numbing drug that lasts a different length of time. The relief has to match the drug. Short-acting drug, short relief. Long-acting drug, longer relief. When doctors follow that plan, the diagnosis holds up. Of patients seen at follow-up, 85% still met the test two years later. Counting everyone who enrolled, it was 75%.5
There is a real trade-off. Stricter rules give better ablation results. But they turn away some people who would have been helped. The expert guideline admitted this without settling it. It noted that trial-grade rules may be stricter than what makes sense in a clinic.2
Rhizotomy: what follows a positive block
Facet rhizotomy, radiofrequency ablation, RFA and medial branch neurotomy all name the same procedure. “Rhizotomy” is a loose name. A true rhizotomy cuts a nerve root. This one heats a small branch. But the name has stuck.
It works by heat. A coated needle with a bare tip is laid along the medial branch under fluoroscopy (live X-ray). A small electric pulse confirms the spot. Then radiofrequency current heats the tissue around the tip and cooks the nerve. The joint itself is not touched. The needle’s angle matters more than patients are usually told. The burn forms around the side of the needle, not off its end. A needle laid along the nerve catches it. One laid across it can miss. The expert guideline counts needle angle as a key to the result.2
What the results look like
One randomized trial compared cooled and standard radiofrequency ablation in 43 patients. Each was picked by one block that gave more than 75% relief. About half got at least a 50% drop in pain at six months. It was 52% with cooled and 44% with standard. That gap was not statistically significant.6 The trial was small, so the error ranges were wide. They ran from about 31% to 74% and 22% to 69%. Treat “about half” as the honest summary and the exact percents as noise.
The evidence is not all good. A randomized, sham-controlled, double-blind trial at several centers tested 60 patients against a fake procedure. It found no significant difference between treatment and sham.7 But those patients were picked with one block that needed only a 2-point drop on a 0–10 scale. That let in many people whose pain was not from the facets. A network meta-analysis pooled 25 trials with 1,969 patients. It ranked endoscopic neurotomy (cutting the nerve through a scope) best for pain relief at 1 and 6 months. Medial branch thermal radiofrequency ablation came next. The authors called for better trials.8
Put it together. The procedure works for some people. How many depends heavily on how they are picked. No one should expect a set number.
Recovery and risk
The procedure takes about 20 to 45 minutes, based on how many levels are treated. Most patients walk out the same day. Expect soreness at the needle sites for several days to two weeks before you see the result.
The complication worth knowing about is post-neurotomy neuritis. It is a burning feeling in the treated area in the weeks after ablation. It usually goes away on its own. Steroid given after ablation has not been shown to reduce it.9 Otherwise the risks are those of any X-ray-guided spine procedure. They are bleeding, infection, a short spell of more pain, and rare injury to a nearby structure.
Medial branches do not feed the arms or legs. They do not carry skin feeling in a nerve-root strip, called a dermatome. So ablating them causes no arm or leg weakness and no numb strip of skin. They do feed the multifidus,2 so ablation cuts off part of the nerve supply to that deep back muscle. That is a reason to take core training afterward more seriously, not less.
How long it lasts
Relief is not permanent, and an honest doctor says so up front. One prospective study followed patients through repeat ablations. On average, the benefit lasted about ten months. Second and third treatments cut pain and disability as well as the first.10 The realistic view: it buys a window, it can be repeated, and it does not change the arthritis underneath.
Who this pathway is not for
Facet treatments aim at one source of pain. They do not treat disc pain. They do not treat pain shooting down a limb from a pinched nerve root. They do not treat sacroiliac joint pain or a nervous system turned up across the board, called central sensitization. A negative block points the search elsewhere. It does not end it. Blocks and ablation also sit inside a bigger plan. That plan builds the core muscles and fixes the loads on the joint. Cutting the nerve to a joint that is still overloaded buys time. It does not fix the load.
If you are in the St. Louis region
Padda Institute, Center for Interventional Pain Management does fluoroscopy-guided (live X-ray) diagnostic blocks and radiofrequency ablation at 4477 Woodson Rd, Suite 100, St. Louis, MO 63134 and 12174 Natural Bridge Rd, St. Louis, MO 63044. Call (314) 481-5000. The procedure pages are facet joint injection and facet joint radiofrequency ablation.
Frequently asked questions
Is a facet joint injection the same as a medial branch block?
No. A medial branch block puts numbing medicine on the two nerves feeding a joint. It asks a test question. An intra-articular injection puts steroid inside the joint itself. It is also meant to treat. Both can give similar short-term relief for different reasons. That is why the difference matters. See the facet joint injection page.
Why does my doctor want two blocks before the rhizotomy?
Because one block is wrong about two times in five. The second block uses a numbing drug that lasts a different length of time. The relief has to match the drug. That screens out placebo responses and numbing spread. People who pass both do better after ablation. See the facet radiofrequency ablation page.
How long does a facet rhizotomy last?
Studies that followed repeat ablations put the average benefit at about ten months. Repeat treatments work about as well as the first. Results vary widely from person to person. The radiofrequency ablation page covers what to expect afterward.
What happens if the block does not relieve my pain?
A negative block is useful. It rules the facet joints out and points the search elsewhere. The sacroiliac joint is an often-missed source of low back and buttock pain. See the sacroiliac joint injection page. Pain radiating below the knee points elsewhere.
Does an MRI showing facet arthritis mean my facet joints are the problem?
No. Facet wear gets common with age. It does a poor job of showing which joint is causing pain. Scans rule out other causes and help plan the needle path. They do not make the diagnosis. If your pain shoots into the leg, a pinched nerve root is more likely. See the epidural steroid injection page.
Will ablating the nerve cause weakness or permanent numbness?
Medial branches do not feed the arms or legs. They do not carry skin feeling in a nerve-root strip. So ablation does not cause arm or leg weakness or a numb strip of skin. These nerves do feed the multifidus, a deep back muscle. That muscle loses part of its nerve supply. That is why core training still matters afterward. The complication to know about is post-neurotomy neuritis. It is a burning feeling in the weeks afterward that usually goes away on its own. Questions about whether you are a candidate belong with the treating doctor. Background on Dr. Gurpreet Singh Padda, MD, MBA, MHP.
Sources
- Manchukonda R, Manchikanti KN, Cash KA, Pampati V, Manchikanti L. Facet joint pain in chronic spinal pain: an evaluation of prevalence and false-positive rate of diagnostic blocks. Journal of Spinal Disorders & Techniques. 2007. PMID 17912133
- Cohen SP, Bhaskar A, Bhatia A, et al. Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group. Regional Anesthesia and Pain Medicine. 2020. PMID 32245841
- Hurley RW, Adams MCB, Barad M, et al. Consensus practice guidelines on interventions for cervical spine (facet) joint pain from a multispecialty international working group. Pain Medicine. 2021. PMID 34788462
- Fogarty AE, Buttner JA, Duszynski B, et al. The effectiveness of fluoroscopically guided lumbar facet steroid joint injections: a systematic review. Interventional Pain Medicine. 2025. PMID 40469068
- Manchikanti L, Singh V, Pampati V. Are diagnostic lumbar medial branch blocks valid? Results of 2-year follow-up. Pain Physician. 2003. PMID 16883373
- McCormick ZL, Choi H, Reddy R, et al. Randomized prospective trial of cooled versus traditional radiofrequency ablation of the medial branch nerves for the treatment of lumbar facet joint pain. Regional Anesthesia and Pain Medicine. 2019. PMID 30777903
- van Tilburg CWJ, Stronks DL, Groeneweg JG, Huygen FJPM. Randomised sham-controlled double-blind multicentre clinical trial to ascertain the effect of percutaneous radiofrequency treatment for lumbar facet joint pain. The Bone & Joint Journal. 2016. PMID 27803230
- Park S, Park JH, Sokpeou N, et al. Radiofrequency treatments for lumbar facet joint syndrome: a systematic review and network meta-analysis. Regional Anesthesia and Pain Medicine. 2025. PMID 39481876
- Kaye AD, Brouillette AE, Howe CA, et al. Efficacy of steroid facet joint injections for axial spinal pain and post radiofrequency ablation neuritis: a systematic review. Current Pain and Headache Reports. 2025. PMID 39982588
- Rambaransingh B, Stanford G, Burnham R. The effect of repeated zygapophysial joint radiofrequency neurotomy on pain, disability, and improvement duration. Pain Medicine. 2010. PMID 20667024
Dr. Gurpreet Singh Padda, MD, MBA, MHP
