The facet joint is located in the bony ring at the back of the spine.
It is made up of processes (which are, in fact, an extension of the bone) that emanate from a pair of interconnected adjacent vertebrae, one above and one below. At each level (called a "segment") there is a connection of the right and left facets. This means that 4 of these processes are involved in the creation of facet joints at any level or segment of the spine. The processes that make up the facet joint are called "joint processes."
The interlocking aspect of the facet joint design makes it a key player in maintaining stability of the entire spine during movement.
The facet joints are also called the zygomatic joints. This word is difficult to pronounce, which is why many people, including healthcare professionals, prefer the term "facet joint."
Facet joint problems are a very common cause of back pain and are generally associated with arthritis of the spine and / or degenerative changes in the spine.
Another back problem, called spondylolisthesis , often begins with a small fracture in a dark area of the facet joint known as the pars. The initial injury is called a pars defect; It is caused by repetitive movements of the spine, such as those performed by young athletes who train hard. (Middle-aged people, especially those who are overweight, are also at risk of developing a pars defect.)
In the absence of control, the pars defect can develop into spondylosis and eventually spondylolisthesis, when one bone becomes destabilized to the point of sliding forward or backward from the adjacent bone.