Facet joint injections and medial branch blocks are performed to diagnose and treat back pain that comes from the spinal facet joints. Facet joint pain is usually pain in the middle of the spine that can radiate down the legs to the knees, and sometimes to the calves (or radiate from the neck to the shoulders and upper back). Facet back pain is usually worse when arching the back or twisting the spine.

A facet joint injection involves placing the local anesthetic in the facet joint itself; whereas, a medial branch block involves depositing local anesthetic at the small, medial nerves to temporarily interrupt the transmission of pain signals sent from the facet joints to the spinal cord. A small dose of corticosteroid is usually mixed with the local anesthetic to provide for more long-term relief than with the local anesthetic alone. Both the facet joint injection and medial branch block are done with fluoroscopy (XRay machine) to allow precise placement of the needle, using bony landmarks as a guide.

Temporary pain relief from the local anesthetic should be experienced within 10 -15 minutes of the procedure. The steroid effect may take several days to experience, but can provide many weeks of back pain relief. There may be a couple of days after the procedure in which there is some increased soreness from the needle placement.

Risks of the procedure are extremely low, but include bleeding, infection, and nerve injury. You should contact your physician should you experience redness or heat at the site of the injection or if you feel significantly more back pain or feel unwell.

The facet joint injection and medial branch blocks should provide more than 50% pain relief from facet joint pain. If the blocks yield only a short duration of significant pain relief, a radiofrequency lesioning procedure of the medial branch nerves can provide as long as 9 months of pain relief should be considered.