Femoral Neck External Size But Not aBMD Predicts Structural and Mass Changes for Women Transitioning Through Menopause
Jepsen, Karl, Andrew Kozminski, Erin Bigelow, Stephen Schlecht, Robert Goulet, Sioban D. Harlow, Jane Cawley, and Carrie Anne Karvonen-Gutierrez. 2017. "Femoral Neck External Size But Not aBMD Predicts Structural and Mass Changes for Women Transitioning Through Menopause." Journal of Bone and Mineral Research, 32(6): 1218-1228.
The impact of adult bone traits on changes in bone structure and mass during aging is not well understood. We hypothesize that age-related changes in bone traits also depend on external bone size. We analyzed hip dual-energy X-ray absorptiometry images acquired longitudinally over 14 years for 198 midlife women transitioning through menopause. The 14-year change in bone mineral content and bone area, but not areal bone mineral density, correlated negatively with baseline femoral neck external size, adjusted for body size using the residuals from a linear regression between baseline bone area and height. The dependence of the 14-year changes in BMC and bone area on baseline bone area remained significant after adjusting for race/ethnicity, postmenopausal hormone use, the 14-year change in weight, and baseline aBMD, weight, height, and age. This suggested that women showed similar changes in aBMD for different structural and biological reasons: women with narrow femoral necks showed smaller changes in BMC but greater increases in bone area compared to women with wide femoral necks who showed greater losses in BMC but without large compensatory increases in bone area. This finding is opposite to expectations that periosteal expansion acts to mechanically offset bone loss. Thus, changes in femoral neck structure and mass during menopause vary widely among women and are predicted by baseline external bone size but not aBMD. How these different structural and mass changes affect individual strength-decline trajectories remains to be determined.