Osteoporosis is a major cause of morbidity and fragility fractures in postmenopausal women. Bone mineral density (BMD) alone may not fully reflect fracture risk and skeletal fragility. Lumican, an extracellular matrix proteoglycan involved in collagen organization and musculoskeletal tissue homeostasis, has emerged as a potential biomarker for bone health. This prospective observational study aims to investigate the relationship between serum lumican levels, bone mineral density, muscle strength, and clinical fragility indicators in postmenopausal women. Approximately 100 participants will undergo routine osteoporosis assessment including DEXA, laboratory testing, FRAX evaluation, and handgrip strength measurement. The study will evaluate whether serum lumican levels can identify a hidden fragility phenotype beyond conventional bone mineral density measurements.