Bone
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A mildly elevated homocysteine (Hcy) level is a novel and potentially modifiable risk factor for age-related osteoporotic fractures. Elevated Hcy levels can have a nutritional cause, such as inadequate intake of folate, riboflavin, pyridoxine or cobalamin, which serve as cofactors or substrates for the enzymes involved in the Hcy metabolism. We examined the association between intake of Hcy-related B vitamin (riboflavin, pyridoxine, folate and cobalamin) and femoral neck bone mineral density BMD (FN-BMD) and the risk of fracture in a large population-based cohort of elderly Caucasians. ⋯ We conclude that increased dietary riboflavin and pyridoxine intake was associated with higher FN-BMD. Furthermore, we found a reduction in risk of fracture in relation to dietary pyridoxine intake independent of BMD. These findings highlight the importance of considering nutritional factors in epidemiological studies of osteoporosis and fractures.
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We conducted a prospective study among elderly women with a first hip fracture to document survival and functional outcome and to determine whether outcomes differ by fracture type. The design was a one-year prospective cohort study in the context of standard day-to-day clinical practice. The main outcome measures were survival and functional outcome, both at hospital discharge and 1 year later. ⋯ Functional outcome differs according to fracture type at hospital discharge, but these differences do not persist over time. These differences cannot be explained by differences in age or comorbidity. To address the mechanism(s) by which intertrochanteric fractures carry excess mortality compared to femoral neck fractures, future studies in hip fracture patients should include a comprehensive assessment of the degree of frailty, vitamin D status, and fall dynamics.
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Knowledge of the location of initial regions of failure within the vertebra - cortical shell, cortical endplates vs. trabecular bone, as well as anatomic location--may lead to improved understanding of the mechanisms of aging, disease and treatment. The overall objective of this study was to identify the location of the bone tissue at highest risk of initial failure within the vertebral body when subjected to compressive loading. Toward this end, micro-CT-based 60-micron voxel-sized, linearly elastic, finite element models of a cohort of thirteen elderly (age range: 54-87 years, 75+/-9 years) female whole vertebrae without posterior elements were virtually loaded in compression through a simulated disc. ⋯ The amount of high-risk tissue was significantly greater in and adjacent to the cortical endplates than in the mid-transverse region. The amount of high-risk tissue in the cortical endplates was comparable to or greater than that in the cortical shell regardless of the assumed Poisson's ratio of the simulated disc. Our results provide new insight into the micromechanics of failure of trabecular and cortical bone within the human vertebra, and taken together, suggest that, during strenuous compressive loading of the vertebra, the tissue near and including the endplates is at the highest risk of initial failure.
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Aromatase inhibitors have demonstrated their superiority to tamoxifen as adjuvant therapy for early breast cancer in postmenopausal women, but are associated with an increased risk of fractures. The aim of our study was to analyze bone loss, bone turnover and their determinants in postmenopausal women treated with anastrozole. We investigated bone loss and bone turnover markers (BTM) in a prospective open cohort study of 118 postmenopausal women treated with anastrozole for an early hormone-dependent breast cancer. ⋯ In osteoporotic women treated simultaneously with anastrozole and risedronate, bone loss was prevented at hip, and increased at the spine (+4.1+/-0.9% [2.3 to 5.9], p=0.008), and BTM decreased (-24%, -39% for CTX, p=0.003 and 0.001 vs. changes in the untreated group). Anastrozole increases bone turnover and induces an accelerated bone loss that is significantly related to the suppression of 17beta-estradiol production induced by aromatase inhibitor. The bisphosphonate risedronate prevents anastrozole induced bone loss.
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Bone mineral density and geometry measurements by volumetric quantitative computed tomography (vQCT) have been utilized in clinical research studies of aging, pharmacologic intervention and mechanical unloading, but there is relatively little information about the association of these measures with hip fracture. To address this issue, we have carried out a study comparing vQCT parameters in elderly Chinese women with hip fractures with measurements in age-matched controls. ⋯ All vQCT measurements discriminated between fractured subjects and age-matched controls. There was no significant difference in predictive strength between volumetric and areal representations of BMD and trabecular and integral vBMD showed comparable discriminatory power, although both of these measures were more correlated to fracture status than cortical vBMD. We found that fractured subjects had larger femoral neck cross-sectional areas, consistent with adaptation to lower BMD in these osteoporotic subjects. The larger neck cross-sectional areas resulted in bending strength indices in the fractured subjects that were comparable or larger than those of the control subjects. In multi-variate analyses, reduced femoral neck cortical thickness and buckling ratio indices were associated with fracture status independently of trabecular vBMD.