Iliac crest trabecular bone volume as predictor for vertebral compressive strength, ash density and trabecular bone volume in normal individuals.

Whole vertebral bodies (L2) and cylindrical trabecular bone samples from the central part of the first lumbar vertebral body (L1) were obtained from 42 normal individuals aged 15-87 years (27 females and 15 males). These bone samples were analyzed by a compression test, and maximum load and stress values were calculated from the load deformation curves. After the compression the ash density of the samples was estimated. For histomorphometric measurements trabecular bone samples from L1 (n = 42) and from the iliac crest (n = 25) were embedded undecalcified, cut in 8 microns sections and stained with Masson trichrome. Trabecular bone volume (TBV) was measured by means of point counting. A significant and parallel age-related decrease in TBV was found in the iliac crest and in the vertebral trabecular bone specimens (p less than 0.001). Highly significant positive correlations were observed between iliac crest TBV and the quantitative vertebral parameters: TBV and ash density (p less than 0.001). Furthermore, the iliac crest TBV was significantly correlated to the qualitative vertebral strength parameters: Vertebral trabecular bone stress, whole vertebral body stress and whole vertebral body load (p less than 0.001). Multiple regression analyses revealed that the vertebral trabecular bone strength was unrelated to bone volume when the influence of age was considered but significantly inversely correlated to age when bone volume was taken into account. This indicates that age-related structural changes other than bone mass affect the vertebral bone strength strongly.