Denosumab is a potent anti-resorptive agent and is now widely used in the treatment of
osteoporosis. Although denosumab has excellent effect to increase bone mass and prevent
fracture in FREEDOM study with very low complications, even up to ten years, it's effect is
reversible. After holding the drug, circulating denosumab levels fall rapidly, and bone
resorption reaching twice baseline levels for about 6 months. How to prevent bone loss after
denosumab therapy is an important issue, especially when considering the compliance,
persistence, or other comorbidities of the patient. We want to verify if zoledronic acid
could be used as a sequential therapy after denosumab to prevent rapid bone loss by
randomized clinical trial.