This invention concerns a novel preparation of amorphous strontium-polyphosphate microparticles ("Sr-a-poly P-MP") that can be used for treatment of osteoporosis after oral administration and as a regeneratively active implant material for bone repair. The inventive particles are morphogenetically active. They induce a multifold higher expression of alkaline phosphatase and bone morphogenetic protein 2 than amorphous calcium-polyphosphate microparticles ("Ca-a-polyP-MP"), but, unexpectedly, the expression of sclerostin, an inhibitor of bone cell differentiation and mineralization is, if at all, only slightly affected, in contrast to "Ca-a-poly P-MP" that strongly increases the expression of this protein. As a result, the inventive particles show a significantly higher stimulatory effect on the growth of human mesenchymal stem cells (MSC) and on mineralization of osteoblast-like SaOS-2 cells compared to "Ca-a-polyP-MP" and the strontium salt. The superior properties of "Sr-a-poly P- MP" compared to "Ca-a-polyP-MP" were confirmed in animal studies which revealed an increased healing/mineralization of bone defects even after short implantation periods. Consequently, the inventive microparticles ("Sr-a-polyP-MP") are potentially applicable both in therapy of osteoporotic patients and bone repair.L'invention concerne une nouvelle préparation de microparticules amorphes de polyphosphate de strontium ("Sr-a-poly P-MP") qui peut être utilisée pour le traitement de l'ostéoporose, par voie orale, et en tant qu'implant actif régénératif pour la réparation osseuse. Les particules de l'invention sont morphogénétiquement actives. Elles induisent une expression plus forte multiple de la phosphatase alcaline et de la protéine morphogénétique osseuse 2 par rapport aux microparticules du polyphosphate de calcium amorphes ("Ca-a-polyP-MP"), mais, de manière inattendue, l'expression de la sclérostine, un inhibiteur de la différenciation et de la minéralisation des cellules osseuses, es
