The facet joints are the joints of the spine. Picture two prongs up and two prongs down on the back portion of each vertebra (spine bone). The top ones interlock with the bottom ones at the vertebra above and so forth. The joints eventually become arthritic as the aging process begins at conception and stops at death. As discs degenerate over time – meaning they dehydrate over time – the facet joints must transfer more of the weight, particularly in the low back more so than the neck. This means that they must “sure up” to accommodate the additional transfer of weight with less disc material for shock absorption. This means that the joints lie down more “cement” or in simple terms more bone with this additional bone formation of the joints referred to as osteoarthritis of the facet joints.
Facet joint-mediated pain is in the midline where the spine is located. It is worse in the seated position since the weight of the upper half of one’s body generates force on the low back while seated much moreso than while lying down. Placing the person’s trunk into extension (arching back) increases lumbar facet joint-mediated pain. A diagnostic and potentially therapeutic test for this is the implementation of a corticosteroid/anesthetic injection under fluoroscopy (x-ray guidance) to evaluate for this as a cause of pain.
Facet joint injuries can and do occur with trauma. In some instances, imaging studies, such as x-rays, MRIs and bone scans can reveal abnormalities of the facet joint. In other cases, injuries occur and are successfully treated even without a significant imaging abnormality. The key in regard to this diagnosis and its causality remains the clinical history and physical examination with characteristics as described within this earlier text.