[Ultrastructural studies of articular cartilaginous degeneration in the facet joints in spinal scoliosis].

The purpose of this study was to determine the relationship between spinal scoliosis and degeneration in the articular cartilage of the intervertebral facet joint. Histological and ultrastructural studies were performed on the articular cartilage of the apical facet joints in the area affected by spinal scoliosis. Histological examinations showed that cartilaginous degeneration in the concave side was more severe than that in the convex side. Over 70 degrees, the histological findings showed increased surface irregularities and hypocellularity in the concave facet joints. A significant correlations were found between the apical degenerative score of the articular cartilage and the pre-operative rotation index and the post-operative correction ratio of the scoliosis. Using transmission electron microscopy (TEM), the development of the organellae of the concave articular cartilage was demonstrated to be commonly disturbed, but the microstructure of the convex cartilage was intact with less than 70 degrees of spinal scoliosis, while similar findings to the concave side were demonstrated over 70 degrees. These results suggest that a biomechanical imbalance disturbed organellae of the cartilage cells in the articular cartilage of the concave apical facet joints initially and this then gradually extended to the convex side over 70 degrees with progressing scoliosis.