  Osteoporosis and fragility fractures have emerged as major public health
concerns in an aging population. However, measuring age-related changes in bone
density using dual-energy X-ray absorptiometry has limited personalized risk
assessment due to susceptibility to interference from various factors. In this
study, we propose an innovative statistical model of bone pixel distribution in
fine-segmented computed tomography (CT) images, along with a novel approach to
measuring bone density based on CT values of bone pixels. Our findings indicate
that bone density exhibits a linear decline with age during adulthood between
the ages of 39 and 80, with the rate of decline being approximately 1.6 times
faster in women than in men. This contradicts the widely accepted notion that
bone density starts declining in women at menopause and in men at around 50
years of age. The linearity of age-related changes provides further insights
into the dynamics of the aging human body. Consequently, our findings suggest
that the definition of osteoporosis by the World Health Organization should be
revised to the standard deviation of age-based bone density. Furthermore, these
results open up new avenues for research in bone health care and clinical
investigation of osteoporosis.
