Medial branch blocks are a special injection to diagnose pain in the lumbar facet joints, which are the joints that connect your vertebrae in the low back. The low back experiences a high level of mobility, and consequently, is prone to the development of arthritis, which results from wear and tear on the joints. This problem typically will cause localized back pain. During a medial branch block a short-acting anesthetic is injected to block the nerves responsible for innervating the facet joint. If you have two positive injections we can move forward with a radiofrequency ablation, which is a more permanent solution to facet joint pain.