Structural trends in the aging proximal femur in Japanese postmenopausal women.

Hip structure analysis (HSA) can be used to measure proximal femur geometry using conventional DXA scans of the hip. This study is the first analysis of HSA data in Japanese women to evaluate apparent age trends in the geometry of cross-sectional regions in the proximal femur. 409 Japanese women aged from 50 to 93 years of age were measured by DXA at three sites (narrow neck, intertrochanter, shaft). Using the mean value those between 50-59 years as a reference value, age trends were evaluated using groupings of 5-year intervals and those over 80 as a single group. BMD at three measured sites and section modulus (index of bending strength) at narrow neck declined in a similar age dependent manner, but section modulus at intertrochanter and shaft showed a different pattern. The decline in section modulus at narrow neck occurs after 50-59 years of age, whereas section modulus at intertrochanter remain 70-74 years, after that began to decrease. Section modulus at shaft, an uncommon fracture location, remains fairly static through life. In conclusion, HSA in Japanese women showed that reduction in geometric strength, as reflected by the section modulus, was not dependent on decline in BMD.