Facet Joint Injections and Medial Branch Blocks

Facet joint injections and medial branch blocks aim to treat pain arising from facet joints in the spine. While facet joint injections are given directly into the facet joint, medial branch blocks target the medial branch nerves that carry pain signals from the facet joints to the brain.

How Facet Joint Injections and Medial Branch Blocks Work

Both facet joint injections and medial branch blocks are used to diagnose and treat pain stemming from facet joints. While treating pain, typically steroids or steroids mixed with anesthetics are used.

See Facet Joint Disorders and Back Pain

The mechanism of pain control is different for facet joint injections and medial branch blocks.

Facet joint injections

Facet joints are surrounded by a joint capsule made up of synovial membrane tissue. This joint capsule contains a rich innervation of nerves and its upper pad is typically fused with the fatty sheath of the spinal nerve.¹Peh W. Image-guided facet joint injection. Biomed Imaging Interv J. 2011;7(1):e4. doi:10.2349/biij.7.1.e4

See Cervical, Thoracic and Lumbar Facet Joint Injections

When the synovial membrane tissue of the joint capsule is inflamed, facet joint injections may:

• Inhibit the production of inflammatory chemicals, reducing pain
• Making pain receptors less sensitive, in turn sending fewer pain signals through the nerves

See Facet Joint Injection Procedure

More than one injection may be given to treat pain stemming from several facet joints.

Medial branch blocks

Medial branch nerves feed out of the spinal nerves’ dorsal rami and typically possess only sensory properties (except for some small branches in the neck that control small muscles). Medial branch nerves richly supply the facet joints. All joint segments below C2-C3 receive medial branch innervation from two levels—the same level as the joint and from a level above the joint.¹Peh W. Image-guided facet joint injection. Biomed Imaging Interv J. 2011;7(1):e4. doi:10.2349/biij.7.1.e4

See All About the C2-C5 Spinal Motion Segments

Injecting steroids near the medial branch nerves may:

• Suppress the nerve from sending pain signals to the brain
• Block specific fibers (C fibers) within the nerve that results in a decrease in pain transmitted to the brain
• Decreases the permeability of nerve fibers to receive blood, decreasing pain transmission

See Medial Branch Nerve Blocks

All the medial branch nerves innervating a joint are treated at the same time.

For both types of injection treatments, diagnostic injections include the injection of an anesthetic medication in order to accurately locate the painful facet joint or the corresponding medial branch nerve(s).

Fluoroscopy or ultrasound guidance is done to guide the needle to the accurate treatment region. A contrast dye may be used to enhance the visualization of the joint and/or nerves.

Success Rates of Facet Joint Injections and Medial Branch Blocks

The success rates of facet joint injections and medial branch blocks vary. Studies show that up to 92% of patients may experience pain-relief for a short duration, typically 1 to 4 weeks after the injection.¹Peh W. Image-guided facet joint injection. Biomed Imaging Interv J. 2011;7(1):e4. doi:10.2349/biij.7.1.e4 Over time, the symptoms may or may not return. Some patients may need repeat injections to sustain the relief period while other patients may experience complete resolution or long-term pain relief.

See Facet Joint Injection Pain Relief Results

In individuals who experience temporary pain relief, these injections can provide a window of opportunity to make progress on physical therapy and other therapies. Improving the neck or back’s strength and flexibility may lead to better function and long-term pain relief.

See Physical Therapy for Low Back Pain Relief

See Physical Therapy for Neck Pain Relief

When Facet Joint Injections and Medial Branch Blocks are Given

Facet joint injections and medial branch blocks may be given to treat the following:

• Facet joint syndrome
• Multilevel spinal pain
• Post-whiplash injury
• Chronic pain with normal radiological findings
• Spondylosis
• Post-surgical pain

It is estimated that 10% to 15% of facet joints receive atypical innervations from nerves other than medial branch nerves. For these individuals, a facet injection could be more effective.²Cohen SP, Moon JY, Brummett CM, White RL, Larkin TM. Medial Branch Blocks or Intra-Articular Injections as a Prognostic Tool Before Lumbar Facet Radiofrequency Denervation. Regional Anesthesia and Pain Medicine. 2015;40(4):376-383. doi:10.1097/aap.0000000000000229

Risks of Facet Joint Injections and Medial Branch Blocks

Risks and complications are rare, although spinal cord damage, phrenic nerve damage, chemical meningitis, bleeding, septic arthritis, and infection are possible. Post-injection pain and numbness may occur but usually resolves in a few hours.

See Risks and Complications of Medial Branch Blocks

See Facet Joint Injection Potential Risks and Complications