StrAtegies For Zoledronic Acid Post-dEnosumab Discontinuation in Postmenopausal oSTeoporosis

Denosumab (Dmab) is a potent and validated treatment for postmenopausal osteoporosis. However, its withdrawal, especially after reaching therapeutic target, is associated with a rebound phenomenon characterized by: (i) an increase in bone turnover markers levels usually within first 6 months off-treatment, (ii) a decrease in BMD, and (iii) an unexpected increased risk of (multiple) vertebral fractures. Although current experts' recommendations propose a post-Dmab bisphosphonates therapy (such as ZOL) to mitigate rebound phenomenon, the optimal strategy is still matter of debate. Data suggesting a protective effect with bisphosphonates (1 infusion of ZOL or weekly alendronate) are scarce, with discrepancies, and highlight that a substantial proportion of patients experiences rebound-related bone loss despite bisphosphonate therapy. Crosslaps, a bone turnover maker, are available for daily clinical practice and reflect the antiresorptive activity of anti-resorptive drugs such as bisphosphonates. Investigator hypothesize that monitoring crosslaps levels, can help to identify patients requiring more intensive bisphosphonate (additional ZOL infusion) therapy to control the post-Dmab rebound phenomenon. Investigator propose to compare 2 strategies for Dmab withdrawal in postmenopausal osteoporosis: a standard treatment control group treated with a single ZOL infusion versus a biomarker-guided ZOL group with an additional ZOL infusion in case of insufficient inhibition of bone resorption according to crosslaps.