Bone Abstracts

Bone strength, hence fracture risk, is dependent on bone geometry, microstructure and bone material level properties. We have reported that microstructure and material level properties contribute independently to the increase in bone strength in rats treated with strontium ranelate for 2 years, as evaluated by μCT-based Finite Element analysis.

We investigated the effects of strontium ranelate (SrRan) treatment on bone material level properties of transiliac bone biopsy from postmenopausal osteoporotic patients in three studies. In a cross-sectional study, 12 specimens (six in 2 g/day SR treated patients for 3 years and six in the placebo group) were analyzed (in the treated group 3 samples were paired). In a longitudinal study, 80 paired biopsies were obtained at baseline, and after 6 or 12 months of treatment with 2 g/day SrRan. Elastic Modulus, Hardness and Working Energy were blindly analyzed by nanoindentation in the middle of the cortex and of trabecular nodes under humid conditions. Significance of differences was evaluated by student t-test.

In the cross sectional study, SrRan treatment was associated with higher cortical Elastic Modulus, Hardness and Working Energy by +11.0% (P=0.05), +28.1% (P=0.0001), and +11.2% (P=0.01) respectively. In three paired biopsies, SrRan for 3 years increased these variables by +21.8±20.8, +48.7±22.8, and +13.8±16.7% respectively, as compared to baseline (cortex). In the longitudinal study, cortical Elastic Modulus, Hardness and Working Energy increased by +20.3±7.4% (P=0.001), +18.3±6.6% (P=0.001), and +13.0±5.7% (P=0.001) after 12 months respectively. Similar differences were observed in trabecular bone, however no significant effects were observed after 6 months of treatment.

Overall, these results detected in 92 human biopsies suggest that changes of bone material level properties in bone specimens collected in patients treated with strontium ranelate could contribute to increased bone strength and to fracture risk reduction.