Title Microarchitecture and nanomechanical properties of trabecular bone after strontium administration in osteoporotic goats

Strontium (Sr) ralenate is a new agent used for the prevention and treatment of osteoporosis. As a boneseeking element, 98% of Sr is deposited in the bone and teeth after oral ingestion. However, the effect of Sr treatment on bone microarchitecture and bone nanomechanical properties remains unclear. In this study, 18 osteoporotic goats were divided into four groups according to the treatment regimen: control, calcium alone (Ca), calcium and Sr at 24 mg/kg (Ca+24Sr), and calcium and Sr at 40 mg/kg (Ca+40Sr). The effects of Sr administration on bone microarchitecture and nanomechanical properties of trabecular bones were analyzed with micro-CT and nanoindentation test, respectively. Serum Sr levels increased sixand tenfold in the Ca+24Sr and Ca+40Sr groups, respectively. Similarly, Sr in the bone increased fourand sixfold in these two groups. Sr administration significantly increased trabecular bone volume fraction, trabecular thickness, and double-labeled new bone area. Sr administration, however, did not significantly change the nanomechanical properties of trabecular bone (elastic modulus and hardness). The data suggested that Sr administration increased trabecular bone volume and improved the microarchitecture while maintaining the intrinsic tissue properties in the osteoporotic goat model.