Connectivity and the elastic properties of cancellous bone

This study addresses the possible significance of trabecular connectivity f or the mechanical quality of cancellous bone. A total of 141 cubic trabecul ar bone specimens collected from autopsy material from 56 individuals witho ut any known bone or metastatic diseases were used. Age variation was in th e range of 14-91 years and a wide range of trabecular architecture was foun d. Each specimen was three-dimensionally reconstructed with a voxel size of either 20 or 25 mu m. Using the detailed three-dimensional reconstructions as input for microstructural finite-element models, the complete elastic p roperties of the trabecular architecture were obtained and maximum and mean stiffness could be calculated. Volume fraction and true three-dimensional architectural measurements of connectivity density and surface density were determined. Connectivity density was determined in an unbiased manner by t he Euler number, which is a topological property. Using multiple regression analysis it was found that volume fraction explained by far the greatest p art (84%-94%) of the variation in both mean and maximum stiffness. When con nectivity density and surface density were included, the correlations incre ased marginally to 89%-95%, Noticeably negative regression coefficients wer e found for connectivity density. The results suggest that, in normal cance llous bone, the connectivity density has very limited value for assessment of elastic properties by morphological variables, but if a relation exists then stiffness decreases with increasing connectivity, (Bone 24:115-120; 19 99) (C) 1999 by Elsevier Science Inc. All rights reserved.