QUANTITATIVE MORPHOLOGY OF THE VERTEBRAL BODY CORTEX

The vertebral bodies consist of two main structures, trabecular and co rtical bone. The histological changes within the spine, especially in cortical bone, leading to osteoporotic fractures remain, however, poor ly understood. Therefore, the complete front column of the spine was r emoved in 26 autopsy cases without skeletal diseases and in 11 cases w ith proven osteoporosis. A sagittal segment prepared through the cente r of all vertebral bodies was undecalcified embedded in plastic, groun d to a 1-mm-thick block and stained using a modification of the von Ko ssa method. The analysis included measurement of the mean cortical thi ckness of both ventral and dorsal shell (from C3 to L5). The qualitati ve investigation of the structure of the cortical ring completed the a nalysis. The skeletally intact specimens had high cortical thickness v alues in the cervical spine (285 +/- 22 mu m), a decrease in the thora cic spine (244 +/- 14 mu m) and an increase in the lumbar spine (290 /- 15 mu m). The mean thickness of the ventral shell is in general hig her than the thickness of the dorsal shell. The cortical thickness of the spine showed no gender-specific differences (P = n.s.). There was a slight decrease in cortical thickness with age; however, this decrea se and the correlation of cortical thickness to age was only significa nt below vertebral body T8 (r = 0.225 to 0.574; P-r < 0.05 to P-r < 0. 005). Most interestingly, osteoporosis is characterized by a significa nt decrease in cortical thickness throughout the whole spine. This dec rease in cortical thickness was more marked in the dorsal shell (P < 0 .05) than in the ventral shell (ventral from C3 to T6 (P < 0.05) below T6 (P = n.s.). We therefore conclude that in osteoporosis, biomechani cal competence is affected by both trabecular bone loss and decrease o f cortical thickness. This suggests that, in addition to trabecular bo ne measurements, the cortical thickness is of special interest for dia gnostic radiological examinations (CT) to yield clues about the risk o f vertebral fractures.