Inside the joint, not at the nerve

A medial branch block anesthetizes the nerve that reports pain from the joint; a facet joint injection instead enters the joint capsule itself, a small, tightly bounded space, and deposits steroid and anesthetic where the synovial lining and cartilage actually sit. That distinction is not academic — it changes what the injection can and cannot tell you. A response here can mean the joint is inflamed and the medication reached it. It cannot rule the joint in or out with anything close to the confidence a comparative medial branch block provides, because volume is limited, capsule integrity varies, and a leak outside the joint muddies what the response means.

When it is a reasonable choice

This procedure earns its place in a few specific situations: an acute inflammatory flare with visible synovitis or effusion on imaging, where treating active inflammation directly makes more sense than testing a nerve first; a patient on anticoagulation where the ablation timeline is not currently workable and a shorter-term option is needed in the meantime; or a joint that has already been confirmed through blocks and ablation but is now flaring acutely between scheduled treatments.

It is worth naming what is usually underneath an acute flare like that: synovial inflammation driven partly by the joint’s own mechanical wear, and partly by the same systemic metabolic inflammation that raises baseline pain sensitivity across the body. A patient who has been putting off care because a job will not allow a mid-week appointment tends to arrive with a more established flare than one who was seen at the first sign of it — which is one more reason timing and access change how a joint like this presents, not just biology.

The evidence, stated plainly

Multispecialty consensus guidelines on lumbar facet pain rate intra-articular steroid injection as carrying weaker supporting evidence than a confirmed medial branch block followed by radiofrequency ablation, and this practice is not going to soften that. Part of the reason is structural rather than pharmacological: the facet joint capsule holds a small, fixed volume, so there is a hard ceiling on how much medication can be delivered and how far it can reach an inflamed synovial lining, where an ablation instead disables the entire nerve line carrying the signal regardless of how much tissue is inflamed. Relief from an intra-articular injection, when it occurs, also tends to run shorter than relief from ablation — weeks to a few months rather than the better part of a year, and repeated dosing carries the same cumulative steroid concerns discussed on the epidural page: effects on bone density and the adrenal axis that accumulate with frequency, not with any single dose. None of that makes the procedure worthless. It makes it a second-line option for a specific clinical picture, not a substitute for the diagnostic pathway that has the stronger data behind it, and a decision that gets made with you rather than defaulted to because it is simpler to schedule.

How it is done

Fluoroscopic guidance is used to walk a needle directly into the joint space, with contrast injected first to confirm intra-articular placement on live imaging before steroid and anesthetic are delivered — the same imaging discipline used everywhere else on this site, because a joint this small does not forgive a needle placed by feel.

What happens on the day

Common questions

Related reading

• Medial branch block
• Radiofrequency ablation
• Facet joint pain
• Metabolic health and pain
• When injections stop working