Beyond bone density: toward an integrated bone- muscle-function framework for fragility fracture prevention.

Fragility fractures are a major clinical and public health challenge in aging societies. Current prevention strategies are commonly organized around skeletal risk assessment and osteoporosis management, yet fracture occurrence and post-fracture outcomes in older adults are also influenced by muscle dysfunction, frailty, fall propensity, physiological reserve, and rehabilitation capacity. This Perspective proposes a bone-muscle-function framework to complement existing osteoporosis-centered approaches to fragility fracture prevention. In this framework, bone represents skeletal strength and structural fragility, muscle represents sarcopenia-related impairment in strength and physical performance, and function represents frailty-related reserve, resilience, fall propensity, and recovery capacity. Osteosarcopenia provides the bone-muscle foundation, whereas the addition of function extends the framework to include broader vulnerability and recovery potential. Rather than simply adding frailty and sarcopenia to osteoporosis assessment, it organizes bone, muscle, and function into a staged framework for risk identification, recovery planning, and secondary prevention.