A facet joint block is an injection used to diagnose and/or confirm the exact source of a patient's back or neck pain.

Using fluoroscopy guidance, the presumed pain-causing facet joint is injected with a steroid medication (to decrease inflammation) and/or a local anesthetic (to numb the area).

If the patient's pain is relieved after the injection, the pain-generating facet joint is presumed to have been identified. A facet joint block may also be used therapeutically to provide pain relief.

Twisting injuries of the spine are the predominant cause of damage to the facet joints.