Facet Syndrome
Facets are bony projections on the back side of the spinal vertebrae that articulate (come in contact) with each other to help stabilize the spine. They make up two of the three-pronged weight-bearing structures of the spine; the third being the vertebral disc itself. Hence, three entities of the spine help to maintain the erect posture in man, namely the disc and a pair of facet joints situated diagonally behind the disc.
Facet syndrome is the term given to the complex of symptoms experienced when these facets are jammed one upon the other in an unnatural pain-producing manner. Often associated with the facet syndrome is degeneration of the disc, particularly of the posterior (toward the back) aspects.
Generally speaking, the pain pattern produced by facet syndrome is diffuse in nature, contrasted to the well-localized pain patterns in disc involvement. Facet syndrome may in fact produce pain in the groin, buttocks, flank, or back of the thigh and may radiate down the leg as far as the knee.
The pain of facet syndrome can be traced to the compressive load directed within the facet articular capsule (the joint where the facets meet). This area in a normal lumbar spine carries an average of 10-20% of the postural load of an individual. However, in facet syndrome and particularly if arthritic degeneration is involved, the joint capsule may carry up to half the postural load leading to stretching within the capsule and subsequent pain.
