MORPHOGENESIS OF VERTEBRAL DEFORMITIES IN INVOLUTIONAL OSTEOPOROSIS -AGE-RELATED, 3-DIMENSIONAL TRABECULAR STRUCTURE

Study Design. The relation between the semiquantitative data of altera tion in three-dimensional trabecular structure and deformities of the vertebral body was analyzed to clarify the morphogenesis of vertebral deformities in involutional osteoporosis. Objectives. To evaluate semi quantitatively the age-related alterations of the three-dimensional st ructure of trabeculae of the vertebral body and to clarify their relat ion to vertebral deformities in involutional osteoporosis. Summary of Background Data. Recent studies have shown that bone fractures and def ormities in osteoporosis do not depend only on a reduced amount of bon e tissue. There is no previous study on the relation between bone defo rmity and the alterations of the three-dimensional structure of trabec ulae. Methods. The second lumbar vertebrae were removed at autopsy fro m 25 patients who had no disease predisposing them to secondary osteop orosis and no severe vertebral deformities. The sections of the verteb ral body were immersed in sodium hypochlorite solution to corrode the bone marrow. Atrophy of trabeculae and increased spacing between trabe culae were evaluated semiquantitatively under stereoscopic microscopy. The authors examined the relation between the semiquantitative data f ound in the autopsy vertebrae and the patterns and frequencies of each deformity of the second lumbar vertebrae in 99 patients with involuti onal osteoporosis. Results. The most frequent vertebral deformity was wedge-shaped vertebrae with compression of the anterosuperior portion, and the alterations of the trabecular structure of the anterosuperior portion were severe and closely related to aging. Severe trabecular a lterations with no relation to aging did not necessarily cause vertebr al deformity. Conclusions. Trabecular abnormality, which is significan tly correlated with aging, may be the necessary and sufficient conditi on for vertebral deformities in involutional osteoporosis.