Spinal stability as defined by the three-column spine concept.

The three-column spine concept is supported by anatomical data from dry European and African skeketons, by experiments on fresh cadaver spines without chemical fixation and by an extensive clinical and surgical experience. There exists an axial and a transverse stability. Axial stability is maintained along a vertical column system: this consists of two columns at the C1-C2 level and three columns from C2 to the sacrum. The anterior column is formed by the vertebral bodies and discs, and the two posterior columns by posterior joints. Transverse stability at the motion segment levels is produced by a coupling of bony buttresses and ligamentous brakes. The three-joint motion segment is characterized by a triangular disposition of joints with opposing joint spaces, thus supporting the articular orthogonal triangulation concept. These observations have a clinical relevance in the field of spinal growth, changes consequent upon wear in spinal joints and clinical instability.