INTERVERTEBRAL VARIATION IN TRABECULAR MICROARCHITECTURE THROUGHOUT THE NORMAL SPINE IN RELATION TO AGE

The vertebral bodies of the complete spine (C-3-L-5) were removed in 2 6 autopsy cases without evidence for primary or secondary bone disease (13 males aged 19-79 years and 13 females aged 17-90 years). A sagitt al segment through the center of all vertebral bodies was embedded und ecalcified in hydroxyethylmethacrylate and processed to so-called surf ace stained block grindings. Histomorphometric analysis of the complet e segment was performed using a computer-assisted image analysis syste m (IBAS 2000). The structural parameters investigated were bone volume (BV/TV) and trabecular interconnection quantificated by trabecular bo ne pattern factor (TBPf). A close correlation of BV/TV and TBPf was fo und in all vertebral bodies irrespective of vertebral region (r = 0.8, p < 0.001). This indicates that the age-related decrease of trabecula r bone mass is primarily the consequence of the transformation from pl ates to rods and the loss of whole trabecular structures. This basic p rinciple is valid throughout the complete spine. However, the systemat ic analysis of vertebral trabecular bone from C-3 to L-5 revealed a si gnificant intervertebral variation of trabecular microarchitecture. Th e density of trabecular structure of cervical vertebrae is much higher than that of thoracic and lumbar vertebrae (p < 0.001). The extent of age related loss of trabecular bone mass and structure showed a decre ase within the spine from the caudal to the cranial region (p < 0.05). The loss of bone volume in individuals between the ages of 30 and 80 years in the lumbar spine was 53%, whereas in the thoracic spine the d ecrease was 41%, and in the cervical spine only 24%. In C-3 and C-4 no significant age-related loss of trabecular structure density was obse rved. The bone volume of a single vertebra was noted to differ from th e mean of its respective vertebral region by as much as 30%. The prese nt study showed that trabecular structure of lumbar vertebrae and its age-related changes only partially represented thoracic and cervical v ertebrae. It was of limited value, especially for the prediction of st ructure of a single unmeasured vertebral body, The consequences for th e prediction of fracture risk were discussed.