Facet joints are hinge-like structures that link the vertebrae. Four facet joints surround each vertebra: two are connected to the upper vertebra, and two are connected to the lower vertebra. Facet joints are made up of two types of bone that smoothly respond to the other and are surrounded by a capsule of connective tissue for lubrication. Degenerative changes can cause inflammation and pain in the months or years following initial spinal surgery.