Facet Joint Injection

A facet joint injection places local anaesthetic (sometimes with a steroid) into or around one of the small paired joints at the back of the spine, the facet joints. These joints can become worn and painful, but facet wear is common on scans and does not always cause symptoms. The injection is used to test whether a particular facet joint is genuinely contributing to a person's back or neck pain.

If numbing a specific facet joint temporarily relieves the pain, that joint is likely to be a source; if it does not, the pain probably comes from elsewhere. Using X-ray guidance to ensure accuracy, the needle is directed to the chosen joint and the anaesthetic delivered. Because a single test can occasionally mislead, specialists sometimes confirm a positive result before proceeding to longer-lasting treatment. A related test, the medial branch block, numbs the small nerves that supply the joint instead of the joint itself.

You lie face down while the skin is numbed and imaging guides the needle to the joint. You may feel pressure or a brief ache. The procedure is short, usually only a few minutes. As with other diagnostic injections, the key information comes afterwards, so you will be asked to monitor and record your pain over the following hours and days. You will be given after-care advice and may need someone to take you home.

Facet joint arthritis is one of the commonest findings on spinal scans and one of the least specific, because so many painless joints look worn. A facet joint injection helps separate a joint that merely looks arthritic from one that is actually generating pain. Confirming the responsible joint can guide targeted treatments, such as a nerve-deactivation (radiofrequency) procedure, rather than treating several joints on guesswork.

• —NICE — Low Back Pain and Sciatica in Over 16s (NG59)
• —Faculty of Pain Medicine, Royal College of Anaesthetists — Standards
• —British Association of Spine Surgeons (BASS)

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.