Rebalancing bone turnover in favour of formation with strontium ranelate: implications for bone strength

This review updates our current knowledge on the mechanism of action of strontium ranelate and analyses the way it rebalances bone turnover and how it influences bone biomechanics. Strontium ranelate is able to increase pre-osteoblast replication, osteoblast differentiation, collagen type I synthesis and bone matrix mineralization probably through a calcium-sensing receptor (CaR)-dependent mechanism. Paralleling this anabolic effect there is inhibition of osteoclast differentiation and activity mediated by an increase in osteoprotegerin (OPG) and a decrease in RANK ligand (RANKL). The overall effect is a rebalanced bone turnover in favour of improved bone geometry, cortical thickness, trabecular bone morphology and intrinsic bone tissue quality, which translates into enhanced bone strength.