Scaling relations between trabecular bone volume fraction and microstructure at different skeletal sites

- Three hundred forty-nine trabecular bone samples were harvested from different skeletal sites.
- Bone volume fraction and several microstructure parameters were calculated in each trabecular bone sample.
- The bone volume fraction-microstructure scaling relations showed only small site-differences and were independent of vertebral fracture status.
- The scaling relations showed a rather universal character for subjects aged 60-69, 70-79, and > 79 years.

In this study, we investigated the scaling relations between trabecular bone volume fraction (BV / TV) and parameters of the trabecular microstructure at different skeletal sites.Cylindrical bone samples with a diameter of 8 mm were harvested from different skeletal sites of 154 human donors in vitro: 87 from the distal radius, 59/69 from the thoracic/lumbar spine, 51 from the femoral neck, and 83 from the greater trochanter. μCT images were obtained with an isotropic spatial resolution of 26 μm. BV / TV and trabecular microstructure parameters (TbN, TbTh, TbSp, scaling indices (< > and σ of α and αz), and Minkowski Functionals (Surface, Curvature, Euler)) were computed for each sample. The regression coefficient β was determined for each skeletal site as the slope of a linear fit in the double-logarithmic representations of the correlations of BV / TV versus the respective microstructure parameter.Statistically significant correlation coefficients ranging from r = 0.36 to r = 0.97 were observed for BV / TV versus microstructure parameters, except for Curvature and Euler. The regression coefficients β were 0.19 to 0.23 (TbN), 0.21 to 0.30 (TbTh), − 0.28 to − 0.24 (TbSp), 0.58 to 0.71 (Surface) and 0.12 to 0.16 (<α>), 0.07 to 0.11 (<αz>), − 0.44 to − 0.30 (σ(α)), and − 0.39 to − 0.14 (σ(αz)) at the different skeletal sites. The 95% confidence intervals of β overlapped for almost all microstructure parameters at the different skeletal sites. The scaling relations were independent of vertebral fracture status and similar for subjects aged 60-69, 70-79, and > 79 years.In conclusion, the bone volume fraction-microstructure scaling relations showed a rather universal character.