Ultrasound(US)-guided Fusion Imaging-Assisted Facet Joint Injections: A Didactical Approach
1 Diagnostic Imaging and Interventional Ultrasound Ospedale Evangelico Internazionale, Genoa, Italy
2 University of Genoa Department of Radiology, Genoa, Italy
- Facet joints (FJs) or zygoapophysial joints (Z-joints) are one of the most ignored joints in the body, but they play a key role in allowing for smooth spine motion.
- Located posterior to the vertebral body, FJs are synovial diarthrosis on the side of the vertebral column nearest from the surface of the skin.
- FJs allow the spine considerable variety of movement and flexibility, but they also prevent excessive or extreme movement, such as hyperextension, hyperflexion, and work against such injuries as whiplash.
- Each spine vertebra communicates with each other with four small arm-like extensions or articulating processes: two pointing up (superior process) and two down (inferior process); the inferior process of the vertebra communicates with the superior process of the vertebra below and the superior process communicates with the vertebra above.
- Together with a disc that sits between the bodies of the two vertebra they form a three joint complex, that consist of vertebral body-disc-vertebral body joint and two facet joints.
- The inner surface of the facet joint serves as an outer wall of an opening or a foramen for a spinal nerve, through which it exits.
- The disc and the junction of the two vertebral bodies serve as an inner wall of this foramen.
- FJ patologic changes can be responsible of 15-40% of Low Back Pain.
- A correct diagnosis can be made with TC or MRI demonstrating inflammation, irritation, swelling, or degenerative changes of facet joints.
- In such cases, FJ intra-articular injections with local anesthetics or anti-inflammatory drugs can be made with diagnostic or therapeutic purpose.