Osteoarthritis (degenerative arthritis) can cause breakdown of cartilage between the facet joints. When the joints move, the lack of the cartilage causes pain as well as loss of motion and stiffness.
The facet joints are located in the back portion (posterior) of the spine. The joints combine with the disc space to create a three-joint complex at each vertebral level. The facet joint consists of two opposing bony surfaces with cartilage between them and a capsule around it that produces fluid.
The combination of the cartilage and the fluid allows the joint to move with little friction. However, facet joint arthritis causes the cartilage to breakdown and the joint movement is associated with more friction. The patient loses motion and as they get stiffer they have more back pain.