Bone Architecture Measured by Fractal Dimension and Connectivity Indices is More Precociously Altered than Mineral Content in the Orchidectomized Rat

Fractal dimension is a powerful tool for measuring the disorganization of the trabecular network in osteoporosis. Forty eight male Wistar rats were studied at 2, 4, 8 and 16 weeks. In each group, 6 rats were orchidectomized (ORX) and 6 sham-operated. The bone mineral content (BMC) was measured by DXA. BMC of the whole body, tibia and femur were reduced at 16 w in the ORX group. Standard histomorphometry and architecture analysis was performed on the tibia (strut identification, star volumes, Euler-Poincare number (E) and Kolmogorov fractal dimension (Dk)). Bone volume was significantly decreased in the ORX from the 4`h w. After 2 w, Dk was the first modified parameter. In the ORX model, Dk appeared the most potent descriptor of trabecular bone disorganization by revealing earliest changes at the network level.