Imaging of the facet joints.

Facet joints have a variable anatomic orientation, and their imaging must be adapted to this variation. They have an important role in the stability and mobility of the spine at all levels. They are the sites of microtrauma leading to degenerative changes. Trauma may cause subluxation, dislocation, and fracture. As synovial joints, they manifest inflammatory processes and can present as part of a systemic disease. The facet joints are a component of a trijoint complex at each motion segment and cannot be separated biomechanically. Their visualization and analysis must be integrated with the adjoining soft tissue, and with neural and bone components.