Lumbar Facet Joint Injections (Medial Branch Blocks)

These injections are performed as a diagnostic test when it is thought that a facet joint or joints is part of the process that is causing the pain. A small amount of a local anesthetic is injected into the joint or over the medial branch nerve to see if this will temporarily relieve your back pain.

How do the facet joints cause pain?

The facet joints are just like any other joint in the body, they are susceptible to acute injury (sprain or strain) as well as degenerative arthritis. In the back, the facet joints may cause low back pain, hip and buttock pain, and leg pain. The pain is especially bad when leaning backwards or twisting your spine. The pain also tends to be worst first thing in the morning and in the evening.


How do medial branch blocks work to control my pain?

The local anesthetic block will only last a few hours. A small amount of steroid may be injected along with the local anesthetic and may provide pain relief from days to months.


What if a facet joint injection does not improve my pain?

Facet joint injections or medial branch blocks are performed to diagnose pain being caused by the facet joints in your back and will not relieve pain caused by intervertebral discs, spinal nerves, or muscles, which can continue to cause pain after the procedure. If your pain is not relieved after the procedure, the facet joints have been ruled out as the source of your pain. If the facet joint injection successfully treat your pain for a significant period of time, they may be repeated as necessary. If the facet joint injection relieves your pain for a short period of time, then you will likely be scheduled for radiofrequency ablation (RFA) of the medial branch nerves.

Common Conditions Treated by Lumbar Facet Joint Injections