Tibia μCT analysis.

Tibia trabecular and cortical bone architecture were assessed by μCT (vivaCT 80, SCANCO Medical AG) using energy settings of 55 kVp, 145 μA, a 0.5 mm Al filter, and an integration time of 250 ms. Images were reconstructed at an isotropic voxel size of 10.4 μm. The trabecular bone volume of interest (VOI) was 145 μCT slices, corresponding to a 1.5 mm region in the longitudinal direction, starting below the growth plate of the proximal tibia. The cortical bone VOI was 97 μCT slices, corresponding to a 1.0 mm region in the longitudinal direction, centered at the tibia middiaphysis. The total tibia lengths were measured from the μCT scout view. Grayscale images were subjected to a Gaussian filter (sigma = 0.8, support = 1) to reduce noise, and a global threshold was applied to binarize grayscale images (36% and 40% maximum grayscale value for trabecular and cortical bone, respectively). The trabecular and cortical VOIs were evaluated by 3D standard microstructural analysis using the manufacturer’s software.