The right hindlimbs of 5 or 6-week old Wistar male rats were sciatic/femoral neurectomized, tenotomized or sham operated. The rats were sacrificed 2 weeks after the surgery and the tibiae were removed. pQCT measurement was performed on total, cortical, and trabecular bone separately at different regions. Reduction of the bone mineral density by unloading was observed more significantly at metaphysis than at diaphysis due to histological heterogeneity between metaphysis and diaphysis; metaphysis is rich in trabecular bone and diaphysis is abundant in cortical bone. Trabecular bone might be more sensitive to unloading because the reduction rate of volumetric bone mineral density in trabecular bone was approximately 10 times and 3 times larger than that of cortical bone in both neurectomy and tenotomy rats, respectively, Unloading also reduced the cross-sectional area and stress strain index at metaphysis.
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