Facet joints are the small paired joints at the back of the spine linking each vertebra to the one above and below, and when one becomes a pain generator no scan or exam maneuver can prove it. The only way to establish the diagnosis is to anesthetize the nerves supplying the joint and see whether the pain goes away — which is why a diagnostic block and a therapeutic injection differ, and why a rhizotomy is only worth considering after a positive block.
What a facet joint is
Each vertebra connects to its neighbors in three places: the disc in front, and a pair of facet joints behind. The facet joints are true synovial joints — cartilage, capsule, synovial lining — roughly the size of a thumbnail. Their job is mechanical: they guide and limit motion, taking load in extension and rotation while the disc takes compression. Being synovial joints they degenerate; having a nerve supply, they can hurt.
That nerve supply is the basis of the entire diagnostic sequence. Each facet joint is innervated by two medial branches — small nerves arising from the dorsal rami at the level of the joint and the level above. Two nerves, one joint: no facet joint has a nerve of its own. This is why a block or ablation aimed at a single joint must target two nerves, and why diagnostic blocks are performed at two levels to test one joint.1
The medial branch is not a purely sensory nerve. Alongside the fibers carrying pain from the joint, it supplies the multifidus muscle, the interspinal muscle and ligament, and the periosteum of the neural arch.2 That matters later: denervating the nerve denervates part of that deep muscle too.
How facet-mediated pain presents
Facet pain is axial. It sits in the neck or low back near the midline and refers in a diffuse regional pattern rather than a sharp radicular one — into the shoulder blade and upper arm from the cervical spine, into the buttock and posterior thigh from the lumbar spine. It usually stops above the knee or elbow and produces no true numbness, weakness, or reflex loss. The pattern is mechanical: worse with extension and rotation, better leaning forward. No single feature is diagnostic.
In a retrospective review of 500 consecutive patients with chronic spinal pain evaluated with controlled comparative anesthetic blocks, 438 met inclusion criteria; among them facet joint pain accounted for 39% of cervical, 34% of thoracic, and 27% of lumbar cases.1 That is a single specialty-clinic population, so the figures overstate what primary care would show — but facet pain is clearly common enough to look for and far from universal.
Why imaging cannot make the diagnosis
Degenerative facet change on CT or MRI becomes common with age and correlates poorly with which joint — if any — is generating pain. The multispecialty consensus guideline on lumbar facet interventions found no pathognomonic history or physical examination finding that reliably predicts response to facet blocks, and no association between significant facet pathology on MRI and denervation outcome.2 The cervical guideline reached the same conclusion, judging the evidence insufficient to diagnose facet-mediated pain by imaging while still recommending imaging for procedural planning.3 This is not a limitation of the scanners: imaging shows structure, and pain is a function of nociception. A joint can look terrible and be silent.
Diagnostic block versus therapeutic injection
These two are often described interchangeably, including on clinic websites. They are not the same.
The medial branch block
A medial branch block places a small volume of local anesthetic on the two medial branches supplying a suspected joint, under fluoroscopy. Nothing therapeutic is intended. The question is binary: with those nerves silenced, does the usual pain go away, and does it return as the anesthetic wears off?
Volume matters: excess anesthetic spreads to structures that were not the target and produces a false positive. Sedation matters: a sedated patient reports relief reflecting the sedative rather than the block. Both were formal questions in the consensus guideline, which also found medial branch blocks more predictive of successful ablation than intra-articular injections.2
The intra-articular facet injection
An intra-articular injection puts steroid and anesthetic inside the joint capsule. It carries both diagnostic and therapeutic intent, and it is what most people mean by “facet injection.” Its therapeutic record is weak: a 2025 systematic review of fluoroscopically guided lumbar intra-articular steroid injections found success rates from 13% to 74%, graded the evidence very low quality, and noted that observational studies suggest benefit while sham-controlled trials have not demonstrated efficacy.4 That spread reflects variable patient selection, not a variable drug.
Why one positive block is often not enough
A single positive block is unreliable. In the series above, single-block false-positive rates were 45% cervical, 42% thoracic, 45% lumbar.1 Roughly two in five people who report relief from one block do not have facet-mediated pain — placebo response, systemic uptake, and anesthetic spread all contribute.
The answer is a controlled comparative block: repeat it on a separate occasion with an anesthetic of different duration and require the relief to track the pharmacology. Short-acting agent, short relief; long-acting, longer. When that protocol is followed the diagnosis is durable — 85% of patients available for follow-up still met criteria two years later, falling to 75% when everyone enrolled is counted.5
There is a real trade-off. Stricter criteria yield better ablation outcomes but reject people who would have benefited. The consensus guideline acknowledged this without resolving it, noting that trial-grade standards may be stricter than what is reasonable in practice.2
Rhizotomy: what follows a positive block
Facet rhizotomy, radiofrequency ablation, RFA, and medial branch neurotomy all name the same procedure. “Rhizotomy” is loose — a true rhizotomy divides a nerve root, while this heats a small branch — but the term is entrenched.
The mechanism is thermal. An insulated needle with an exposed tip is positioned along the course of the medial branch under fluoroscopy, position is confirmed with electrical stimulation, and radiofrequency current heats the tissue around the tip, coagulating the nerve. The joint is not touched. Orientation matters more than patients are usually told: the lesion forms around the shaft of the needle rather than off its end, so an electrode placed parallel to the nerve captures it and one placed across it can miss. The consensus guideline treats electrode orientation as a determinant of outcome.2
What the results look like
A randomized trial comparing cooled and traditional radiofrequency ablation, in 43 patients selected by a single block requiring greater than 75% relief, found about half achieved at least a 50% reduction in pain at six months — 52% cooled, 44% traditional, not a statistically significant difference.6 The trial was small and the confidence intervals correspondingly wide, spanning roughly 31% to 74% and 22% to 69%; treat “about half” as the honest summary and the exact percentages as noise.
The evidence is not uniformly favorable. A randomized, sham-controlled, double-blind multicenter trial in 60 patients found no significant difference between treatment and sham.7 Patients there were selected with a single block requiring only a 2-point drop on a 0–10 scale — permissive enough to admit many whose pain was not facet-mediated. A network meta-analysis of 25 trials covering 1,969 patients ranked endoscopic neurotomy highest for pain reduction at 1 and 6 months, with medial branch thermal radiofrequency next, while calling for higher-quality trials.8
Taken together: the procedure works for a subset of people, the size of that subset depends heavily on selection, and no one should expect a specific number.
Recovery and risk
The procedure takes roughly 20 to 45 minutes depending on how many levels are treated, and most patients walk out the same day. Expect soreness at the needle sites for several days to two weeks before the result becomes visible.
The complication worth knowing about is post-neurotomy neuritis: a burning discomfort in the treated area appearing in the weeks after ablation, which typically resolves on its own. Corticosteroid given after ablation has not been shown to reduce it.9 Otherwise the risks are those of any fluoroscopically guided spinal procedure — bleeding, infection, transient increased pain, rare injury to an adjacent structure.
Medial branches do not supply the limbs and do not carry dermatomal sensation, so ablating them causes no arm or leg weakness and no numb patch in a dermatomal distribution. They do supply the multifidus,2 so denervation partially deinnervates that deep segmental muscle — a reason to take trunk conditioning afterward more seriously, not less.
How long it lasts
Relief is not permanent, and honest counseling says so up front. In a prospective series followed through repeated neurotomies, the average duration of benefit was approximately ten months, and second and third treatments reduced pain and disability as effectively as the first.10 The realistic frame: a procedure that buys a window, can be repeated, and does not alter the underlying arthropathy.
Who this pathway is not for
Facet interventions target one pain generator. They do not address disc-mediated pain, radicular pain from a compressed nerve root, sacroiliac joint pain, or diffuse central sensitization; a negative block redirects the workup rather than ending it. Blocks and ablation also sit inside a broader plan that includes conditioning the trunk musculature and correcting the mechanical loads on the joint. Denervating a still-overloaded joint buys time; it does not fix the loading.
If you are in the St. Louis region
Padda Institute, Center for Interventional Pain Management performs fluoroscopically guided diagnostic blocks and radiofrequency ablation at 4477 Woodson Rd, Suite 100, St. Louis, MO 63134 and 12174 Natural Bridge Road, Bridgeton, MO 63044, reachable at (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 anesthetic on the two nerves supplying a joint and asks a diagnostic question. An intra-articular injection puts steroid inside the joint itself and carries therapeutic intent too. They can produce similar short-term relief for different reasons, which is why the distinction matters. See the facet joint injection page.
Why does my doctor want two blocks before the rhizotomy?
Because a single block is wrong roughly two times in five. Repeating it with an anesthetic of different duration, and requiring relief to match the drug’s pharmacology, filters out placebo responders and anesthetic spread. People who pass both do better after ablation — see the facet radiofrequency ablation page.
How long does a facet rhizotomy last?
Published follow-up of repeated neurotomies puts the average duration of benefit at roughly ten months, with repeat treatments working about as well as the first. Individual results vary widely. 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 redirects attention elsewhere. The sacroiliac joint is a frequently 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. Degenerative facet change becomes common with age and correlates poorly with which joint is generating pain. Imaging excludes other causes and plans the needle path; it does not make the diagnosis. If your pain radiates into the leg, a nerve-root process is more likely — see the epidural steroid injection page.
Will ablating the nerve cause weakness or permanent numbness?
Medial branches do not supply the limbs and do not carry dermatomal sensation, so ablation does not cause arm or leg weakness or a dermatomal numb patch. These nerves do supply the multifidus, a deep segmental back muscle, so that muscle is partly denervated — which is why trunk conditioning still matters afterward. The complication to know about is post-neurotomy neuritis, a burning discomfort appearing in the weeks afterward that usually resolves on its own. Candidacy questions belong with the treating physician — 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
