Abstract: BACKGROUND: Bone mineral density measured by dual-energy X-ray absorptiometry is the gold standard for diagnosing osteoporosis. The hip is an important site for osteoporosis and fractures. Bone mineral density can only reflect 70% of bone strength. Hip geometric mechanical parameters also have an important impact on hip fractures.
OBJECTIVE: To observe the changes in bone mineral density and geometry of the proximal femur of female subjects and their value in predicting fracture risk through a large sample of female data in Chengdu, and to provide a reference for the prevention and treatment of osteoporosis and hip fractures. 
METHODS: Bone mineral densities of 37 682 women aged 20 to 104.3 years were measured using Prodigy Advance dual-energy X-ray absorptiometry (GE LUNAR, USA). Measurement sites included the left femoral neck, greater trochanter, Wards area, femoral shaft, and total hip. The hip structure analysis software of the dual-energy X-ray absorptiometry was used to measure the geometric structure parameters of the proximal femur, including hip axis length, cross-sectional moment of inertia, femur strength index, neck-shaft angle, and cross-sectional area, to explore the relationship between age, body mass index and proximal femoral bone mineral density and geometry.  
RESULTS AND CONCLUSION: (1) The bone mineral density of the femoral neck, greater trochanter, and total hip in women peaked at ages 30 to 39 and gradually decreased with increasing age. Hip axis length, cross-sectional moment of inertia, cross-sectional area, and femur strength index peaked at ages 30 to 39 and gradually decreased with age. (2) With increasing body mass index, bone mineral density at hip skeletal sites gradually increased, and the detection rate of osteoporosis gradually decreased. (3) With increasing body mass index, hip axis length, cross-sectional moment of inertia, and cross-sectional area of the femoral neck gradually increased (P < 0.001), and the femur strength index gradually decreased (P < 0.001). (4) Hip bone mineral density showed a positive correlation with height, body mass, and body mass index (r=0.095-0.425) and a negative correlation with age (r=-0.445 to -0.623). The hip axis length, cross-sectional moment of inertia, and cross-sectional area were positively correlated with height, body mass, body mass index, and hip bone mineral density (r=0.059-0.444), and negatively correlated with age (r=-0.055 to -0.555). (5) This data provided reference values for hip bone mineral density and geometric parameters in the Chengdu region. There was a loss of bone mineral density and changes geometry in women with increasing age, which become more pronounced after age 50. Women with low body mass index should be particularly cautious regarding the prevention of osteoporosis and fracture risk.

Key words: dual-energy X-ray absorptiometry, bone mineral density, proximal femur, geometry, body mass index, osteoporosis, age