Microarchitecture and Bone Geometry Analysis

To evaluate trabecular microarchitecture and cortical bone geometry of the tibia from control and DSS-treated mice, we used microCT (Skyscan 1172 X-ray microtomograph, Bruker, Kontich, Belgium) as described previously [43 (link)]. In brief, high-resolution scans with an isotropic voxel size of 5 µm were acquired (60 kV, 0.5 mm aluminium filter, 0.6° rotation angle). Two images were averaged at each rotation angle. Scan reconstruction was conducted using NRecon software (Bruker) and each bone was analysed using CtAN (Bruker). For the trabecular analysis, the base of the growth plate was used as a standard reference point. A 1.25 mm trabecular bone region, located at 5% of the total length beneath this reference point, was analysed. To investigate the changes in the cortical bone geometry, two 0.5 mm sections were analysed at 37% and 50% of the total bone length from the reference starting slice (first appearance of the medial tibial condyles). To assess BMD, phantoms were used to calibrate the CTAn software. BMD phantoms of known calcium hydroxyapatite mineral densities of 0.25 and 0.75 g/cm³ were scanned and reconstructed using the same parameters as used for bone samples.