This study is a prospective, randomized, controlled clinical trial comparing the efficacy of a 24-month cyclic therapy regimen (6 months of Romosozumab followed by 6 months of Denosumab, repeated for two years) versus a traditional sequential treatment regimen (12 months of Romosozumab followed by 12 months of Denosumab). The goal is to determine which approach yields better therapeutic outcomes and to optimize drug strategies for osteoporosis patients.

Osteoporosis is common in postmenopausal women and the elderly, and has been recognized by the World Health Organization as the second most prevalent metabolic bone disease worldwide. Most patients show no obvious symptoms, but a fall or sudden exertion can cause fragility fractures. Once fractures occur, complications such as acute pain, prolonged bed rest, and restricted mobility can significantly impact the quality of life and even increase mortality. Furthermore, managing these conditions requires substantial medical and social resources.

Currently, anti-osteoporosis medications are classified into two major categories: antiresorptive and anabolic agents. Studies have confirmed that both types can increase bone mineral density (BMD) and reduce fracture risk. However, each medication has usage limitations.

Denosumab is a potent antiresorptive drug, but long-term use can lead to rare side effects such as atypical femoral fractures (AFF) and medication-related osteonecrosis of the jaw (MRONJ). Additionally, stopping Denosumab can cause a severe rebound in bone resorption markers (CTX), leading to rapid BMD loss and an increased fracture risk. Managing drug discontinuation remains a major clinical challenge.

Inclusion Criteria:

• 1. Postmenopausal women aged 50-90 years
• 2. BMD T-score ≤ -3.0 at any lumbar vertebra
• 3. Physically and mentally capable of understanding and complying with the study protocol and follow-up
• 4. Signed informed consent

Exclusion Criteria:

• 1. Previous osteoporosis treatment within the past two years, including Romosozumab, Teriparatide, Denosumab, Alendronate, Ibandronate, Zoledronic Acid, Risedronate, Raloxifene, or Bazedoxifene
• 2. Allergy to Romosozumab or Denosumab
• 3. Secondary osteoporosis
• 4. Autoimmune disease
• 5. Chronic steroid use (e.g., Chronic Obstruction Pulmonary Disease patients)
• 6. Hypercalcemia or hypocalcemia
• 7. Metabolic bone diseases
• 8. Primary or metastatic bone tumors
• 9. Cancer patients (except for in situ carcinoma and non-melanoma skin cancer, unless fully treated and in remission for five years)
• 10. Planned dental procedures (e.g., extractions, implants) within the next year
• 11. History of stent placement, myocardial infarction, stroke, or coronary artery disease
• 12. Renal disease (Creatinine > 1.5 mg/dL) or dialysis patients
• 13. Smoking more than one pack per day (except for those who have quit for over ten years)