Facet Joint Arthritis
The motion segment between two vertebrae is formed by the intervertebral disc at the front and the two facet joints at the back. The disc is a special fibrous joint and is quite different to the common synovial joints that join the bones of the skeleton. The facet joints are much like the other common synovial joints in the body. The surfaces of the bones are capped by a smooth glistening articular cartilage and there is a capsule of fibrous tissue that contains the joint and an inner membrane that makes fluid to lubricate the joint.
Facet joints are therefore prone to the same conditions that affect the other synovial joints. Like the knee and the hip and the finger joints, facet joints can develop both wear and tear (degenerate) osteoarthritis and can be affected by inflammatory conditions of the joints like rheumatoid arthritis.
All synovial joints degenerate with age. Some joints , like the weight-bearing joints of the hip and knee, seem to wear earlier than other joints. The facet joints of the spine take more load as we age because the discs are also degenerating and as they lose hydration and height the facet joints have to take more load. This is most common in the lower segments of the lumbar spine where the loads are greatest.
Whilst facet joint arthritis is quite common on imaging studies of older spines, it does not seem to be painful for most people. When it does cause pain and stiffness the symptoms seem to be worse in an extended spine position (ie bending backward) where the facet joints are loaded. Relief is achieved in a flexed spine position (ie bending forward). It is uncommon to find patients with a pure extension pattern pain (
