Osteoarthritis of the facet joints

Abstract

The displaced nuclear material from a disc prolapse heals by fibrosis and shrinkage. This reduces the thickness of the disc and is represented in radiographs as joint space narrowing. The relationship between adjacent vertebrae has been described at great length in this monograph to emphasize that the intervertebral disc cannot be regarded in isolation, but as part of a complex arrangement between vertebrae involving also the two posterior intervertebral joints (apophyseal or facet joints) and various ligaments. The whole is a dynamic system allowing movement to take place in a controlled manner between two vertebrae in eight directions — a situation quite different from the concept that regards the disc only as a shock-absorber for compressive forces. As Cyriax (1969) explains, the ankle joint is subject to more of the body mass than individual vertebrae yet manages extremely well without a shock-absorbing disc. As the disc, facet joints and ligaments function together, a derangement of one sooner or later affects the others. Kapandji’s diagram (1974) is well worth repeating as it shows one of the mechanisms said to connect the individual functions of the various units making up the total joint between adjacent vertebrae (Figure 14.1).