MicroCT analyses of mouse femoral neck architecture

Hip fractures at the femoral neck are a major cause of morbidity and mortality, but aside from biomechanical strength testing, little is known about femoral neck architecture in mice. Procedures were optimized to analyze high-resolution (6 μm voxel size) microCT scans of the mouse femoral neck to provide bone mass and architectural information. Similar to histomorphometric observations in rats, the boundary between cortical and trabecular bone is difficult to identify in the mouse femoral mid-neck and these compartments were not analyzed separately. Analyses included total area, mineralized bone area, and bone volume fraction (BV/TV). Femoral neck architecture varies in C57BL/6J, 129/SvEv and BALB/c mouse strains. Bone cross sectional area and BV/TV were low in Lrp5 but elevated in Sost gene knockout mice. Sfrp4 gene knockout resulted in high total area, normal bone area, low BV/TV and, as indicated by BS/BV values, greater trabecularization. Femoral neck BV/TV declined with age and ovariectomy, but increased with teriparatide treatment. These findings demonstrate that the architecture of the mouse femoral neck mimics phenotypes and treatment effects observed at other skeletal sites and is a relevant bone site for translational studies examining osteoporosis therapies.