> What are Facet Joints?
Zygapophysial joints, better known as facet or “Z” joints, are located on the back (posterior) of the spine on each side of the vertebrae where it overlaps the neighboring vertebrae. The facet joints provide stability and give the spine the ability to bend and twist. They are made up of the two surfaces of the adjacent vertebrae, which are separated by a thin layer of cartilage. The joint is surrounded by a sac-like capsule and is filled with synovial fluid (a lubricating liquid that reduces the friction between the two bone surfaces when the spine moves and also nourishes the cartilage.)

> What is a Medial Branch Nerve?
Facet Joints are innervated or “supplied” by nerves called “medial branches”. These nerves carry the pain signals to the spinal cord and the signals eventually reach the brain, where the pain is noticed.

> What is the purpose of it?
If the nerves are “blocked” or “numbed”, they will not be able to carry pain sensation to the spinal cord. It is like temporarily cutting off “wires”. Therefore, if the pain is due to facet joint arthritis, you should have relief from pain and stiffness.

Once it is determined that the pain is indeed due to facet joint disease, we can use a procedure called “Radio-Frequency Lesioning” and prevent the conduction of pain information for several weeks to months.

So, the medial branch nerve block is a temporary and diagnostic procedure.