Structural adaptation to changing skeletal load in the progression toward hip fragility: the study of osteoporotic fractures

摘要: Longitudinal, dual-energy X-ray absorptiometry (DXA) hip data from 4187 mostly white, elderly women the Study of Osteoporotic Fractures were studied with a structural analysis program. Cross-sectional geometry and bone mineral density (BMD) measured in narrow regions across femoral neck proximal shaft We hypothesized that altered skeletal load should stimulate adaptive increases or decreases section modulus (bending strength index) dimensional details would provide insight into fragility. Weight change approximately 35 years between scan time points was used as primary indicator load. "Static" weight defined within 5% baseline weight, whereas "gain" 'loss" those who gained lost >5%, respectively. In addition, we frailty index to better identify subjects undergoing changing loading. Subjects classified frail if unable rise chair five times without using arm support. both (reduced loading) compared not either maintained (unchanged (increased loading). Sixty percent (n = 2,559) unchanged loads BMD at but shaft, while moduli increased slightly regions. increasing 580) BMD; markedly locations. Those declining 105) showed greatest loss shaft; caused by mass greater subperiosteal expansion; decline only mass. This group also significant declines sites. These results support contention mechanical homeostasis is evident density. The response loads, rates expansion cortical thinning, may increase fragility beyond expected reduction alone.