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Query: UNIPROT:P50502 (Hip)
 7,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vertebral fractures are the most common osteoporotic fracture. Hip and clinical fractures are less common in black women, but there is little information on vertebral fractures. We studied 7860 white and 472 black women >or=65 yr of age enrolled in the Study of Osteoporotic Fractures. Prevalent vertebral fractures were identified from lateral spine radiographs using vertebral morphometry and defined if any vertebral height ratio was >3 SD below race-specific means for each vertebral level. Information on risk factors was obtained by questionnaire or examination. Lumbar spine, total hip, and femoral neck BMD and BMC were measured by DXA. The prevalence of vertebral fractures was 10.6% in black and 19.1% in white women. In age-adjusted logistic regression models, a 1 SD decrease in femoral neck BMD was associated with 47% increased odds of fracture in black women (OR = 1.47; 95% CI, 1.12-1.94) and 80% increased odds in white women (OR = 1.80; 95% CI, 1.68-1.94; interaction p = 0.14). The overall lower odds of fracture among black women compared with white women was independent of femoral neck BMD and other risk factors (OR = 0.51; 95% CI, 0.37-0.72). However, the prevalence of vertebral fractures increased with increasing number of risk factors in both groups. The prevalence of vertebral fractures is lower in black compared with white women but increases with age, low BMD, and number of risk factors.
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PMID:Prevalent vertebral fractures in black women and white women. 1844 9

This study was undertaken to determine the influence of proximal femur geometry on hip fracture risk independent of bone mineral density. We examined 34 hip fracture subjects (17 men, 17 women) and 36 control subjects (18 men, 18 women). The control subjects were matched with the hip fracture patients by femoral neck bone mineral density (+ or - 0.100 g/cm(2)). Hip axis length (HAL), femoral axis length (FAL), femoral neck-shaft angle (Theta angle), lateral and medial femoral cortical thickness were measured on standart pelvic radiographs. In the literature, there are conflicting views of the relationship between femur geometry and hip fracture risk which may be explained by different definitions of some parameters. We investigated the effect of a new parameter called true moment arm (TMA) on hip fracture risk. Longer TMA may be correlated to higher transmission of impact energy to the femoral neck. Thus it may be useful to define fracture prone individuals. The results of this study showed that HAL, FAL and TMA were significantly longer in the hip fracture subjects compared to the control group (p<0.001). Hip fracture patients had thinner lateral and medial femoral cortical thickness (p<0.001). Theta angle was wider in the hip fracture group than in the control group (p<0.001). In conclusion, our study showed that evaluation of TMA in addition to HAL, FAL, Theta angle, MCT and LCT can be used to determine of the fracture risk independently of BMD.
Hip Int
PMID:A new value of proximal femur geometry to evaluate hip fracture risk: true moment arm. 1864 83

The role of bone tissue's geometric distribution in hip fracture risk requires full evaluation in large population-based datasets. We tested whether section modulus, a geometric index of bending strength, predicted hip fracture better than BMD. Among 7474 women from the Study of Osteoporotic Fractures (SOF) with hip DXA scans at baseline, there were 635 incident hip fractures recorded over 13 yr. Hip structural analysis software was used to derive variables from the DXA scans at the narrow neck (NN), intertrochanter (IT), and shaft (S) regions. Associations of derived structural variables with hip fracture were assessed using Cox proportional hazard modeling. Hip fracture prediction was assessed using the C-index concordance statistic. Incident hip fracture cases had larger neck-shaft angles, larger subperiosteal and estimated endosteal diameters, greater distances from lateral cortical margin to center of mass (lateral distance), and higher estimated buckling ratios (p < 0.0001 for each). Areal BMD, cross-sectional area, cross-sectional moment of inertia, section modulus, estimated cortical thickness, and centroid position were all lower in hip fracture cases (p < 0.044). In hip fracture prediction using NN region parameters, estimated cortical thickness, areal BMD, and estimated buckling ratio were equivalent (C-index = 0.72; 95% CI, 0.70, 0.74), but section modulus performed less well (C-index = 0.61; 95% CI, 0.58, 0.63; p < 0.0001 for difference). In multivariable models combining hip structural analysis variables and age, effects of bone dimensions (i.e., lateral distance, subperiosteal diameter, and estimated endosteal width) were interchangeable, whereas age and neck-shaft angle were independent predictors. Several parsimonious multivariable models that were prognostically equivalent for the NN region were obtained combining a measure of width, a measure of mass, age, and neck-shaft angle (BMD is a ratio of mass to width in the NN region; C-index = 0.77; 95% CI, 0.75, 0.79). Trochanteric fractures were best predicted by analysis of the IT region. Because section modulus failed to predict hip fracture risk as well as areal BMD, the thinner cortices and wider bones among those who fractured may imply that simple failure in bending is not the usual event in fracture. Fracture might require initiation (e.g., by localized crushing or buckling of the lateral cortex).
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PMID:Prediction of incident hip fracture risk by femur geometry variables measured by hip structural analysis in the study of osteoporotic fractures. 1868 92

Successful aging is multidimensional, and many phenotypes have been proposed. We examined a biomarker of aging based on repeated measures of BMD for up to 15 yr and hypothesized that maintenance of BMD will be associated with low fracture risk and disability and improved survival. We studied 9704 women recruited at four U.S. clinical centers and enrolled in the Study of Osteoporotic Fractures, a longitudinal cohort study. Of these, 8224 women had at least one hip BMD measurement. Hip BMD was measured a maximum of five times over 15 yr. Random effects regression was used to determine a BMD slope for each subject. Three groups were formed-"maintained" BMD: slope >or=0, n = 724 (9%); "expected" BMD loss: slope <0 to <1 SD below mean, n = 6478 (79%); and "accelerated" BMD loss: slope >or=1 SD below mean, n = 1022 (12%). Cox proportional hazards models were used to compare the relative hazard (RH; 95% CI) of fracture, incident mobility disability, and mortality in the maintained and accelerated groups compared with the expected. A 1 SD decrease in the BMD slope was associated with an increased risk of all outcomes. In multivariate models, the RH of nonspine fracture was 0.81 (0.71-0.93) and of hip fracture was 0.36 (0.25-0.53) for women in the maintained compared with the expected group. The incidence of mobility disability was lower in the maintained versus expected group (RH = 0.70; 95% CI = 0.59-0.83), but this was largely explained by other factors. Women who experienced accelerated bone loss were more likely to develop disability (RH = 1.56; 95% CI: 1.33-1.84). Mortality risks were lower in the maintained compared with the expected group (RH = 0.49; 95% CI: 0.42-0.58). In conclusion, a subset of older women maintained their BMD up to 15 yr, suggesting that bone loss is not an inevitable consequence of aging. These women experienced a lower risk of fractures, disability, and mortality, suggesting that this phenotype may be a marker of successful aging.
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PMID:Successful skeletal aging: a marker of low fracture risk and longevity. The Study of Osteoporotic Fractures (SOF). 1871 37

Several DXA-based structural engineering models (SEMs) of the proximal femur have been developed to estimate stress caused by sideway falls. Their usefulness in discriminating hip fracture has not yet been established and we therefore evaluated these models. The hip DXA scans of 51 postmenopausal women with hip fracture (30 femoral neck, 17 trochanteric, and 4 unspecified) and 153 age-, height-, and weight-matched controls were reanalyzed using a special version of Hologic's software that produced a pixel-by-pixel BMD map. For each map, a curved-beam, a curved composite-beam, and a finite element model were generated to calculate stress within the bone when falling sideways. An index of fracture risk (IFR) was defined over the femoral neck, trochanter, and total hip as the stress divided by the yield stress at each pixel and averaged over the regions of interest. Hip structure analysis (HSA) was also performed using Hologic APEX analysis software. Hip BMD and almost all parameters derived from HSA and SEM were discriminators of hip fracture on their own because their ORs were significantly >1. Because of the high correlation of total hip BMD to HSA and SEM-derived parameters, only the bone width discriminated hip fracture independently from total hip BMD. Judged by the area under the receiver operating characteristics curve, the trochanteric IFR derived from the finite element model was significant better than total hip BMD alone and similar to the total hip BMD plus bone width in discriminating all hip fracture and femoral neck fracture. No index was better than total hip BMD for discriminating trochanteric fractures. In conclusion, the finite element model has the potential to replace hip BMD in discriminating hip fractures.
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PMID:Use of DXA-based structural engineering models of the proximal femur to discriminate hip fracture. 1876 24

Proximal load transfer and the absence of distal fixation of the stem are crucial to obtain the best behaviour of the femoral bone after total hip replacement. In this study, dual energy X-ray absorptiometry (DEXA) was employed to understand and compare the bone density changes and thus the re-distribution of mechanical forces in two different extra short stems. Two cohorts of ten patients were included in this retrospective study. Both implants are custom-made and present a well defined lateral flare. The first model is fully coated and presents a short stem (Group A), the second is an unstemmed metaphyseal implant with a polished tip (Group B). DEXA scans were obtained in all patients at the two-year follow-up. A higher BMD was detected in ROIs 1, 2, 4, 5 in Group B confirming a preservation of the proximal bone mass and thus indirectly a more proximal load transfer. The results obtained confirm the importance of the geometry of the implant on proximal bone density. Loading both medial and lateral proximal femoral flares and the complete absence of the diaphyseal portion of the stem provide the optimal bone remodelling of the femur after total hip replacement.
Hip Int 2006
PMID:Bone preservation with a conservative metaphyseal loading implant. 1921 16

Hip fracture risk rises 100- to 1000-fold over six decades of age, but only a minor part of this increase is explained by declining BMD. A potentially independent cause of fragility is cortical thinning predisposing to local crushing, in which bone tissue's material disintegrates at the microscopic level when compressed beyond its capacity to maintain integrity. Elastic instability or buckling of a much thinned cortex might alternatively occur under compression. In a buckle, the cortex moves approximately at right angles to the direction of load, thereby distorting its microstructure, eventually to the point of disintegration. By resisting buckling movement, trabecular buttressing would protect the femoral neck cortex against this type of failure but not against crushing. We quantified the effect of aging on trabecular BMD in the femoral neck and assessed its contribution to cortical elastic stability, which determines resistance to buckling. Using CT, we measured ex vivo the distribution of bone in the midfemoral necks of 35 female and 33 male proximal femurs from cases of sudden death in those 20-95 yr of age. We calculated the critical stress sigma(cr), at which the cortex was predicted to buckle locally, from the geometric properties and density of the cortical zone most highly loaded in a sideways fall. Using long-established engineering principles, we estimated the amount by which stability or buckling resistance was increased by the trabecular bone supporting the most stressed cortical sector in each femoral neck. We repeated these measurements and calculations in an age- and sex-matched series of femoral necks donated by women who had suffered intracapsular hip fracture and controls, using histological measurements of cortical thickness to improve accuracy. With normal aging, trabecular BMD declined asymmetrically, fastest in the supero-lateral one-half (in antero-posterior projection) of the trabecular compartment. When viewed axially with respect to the femoral neck, the most rapid loss of trabecular bone occurred in the posterior part of this region (supero-posterior [S-P]), amounting to a 42% reduction in women (34% in men) over five decades of adult age. Because local cortical bone thickness declined comparably, age had no significant effect on the relative contributions of cortical and trabecular bone to elastic stability, and trabecular bone was calculated to contribute 40% (in men) and 43% (in women) to the S-P cortex of its overall elastic stability. Hip fracture cases had reduced elastic stability compared with age-matched controls, with a median reduction of 49% or 37%, depending on whether thickness was measured histologically or by CT (pQCT; p < 0.002 for both). This effect was because of reduced cortical thickness and density. Trabecular BMD was similar in hip fracture cases and controls. The capacity of the femur to resist fracture in a sideways fall becomes compromised with normal aging because cortical thickness and trabecular BMD in the most compressed part of the femoral neck both decline substantially. This decline is relatively more rapid than that of femoral neck areal BMD. If elastic instability rather than cortical crushing initiates the fracture event, interventions that increase trabecular bone in the proximal femur have great potential to reduce fracture risk because the gradient defining the increase in elastic stability with increasing trabecular BMD is steep, and most hip fracture cases have sufficient trabecular bone for anabolic therapies to build on.
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PMID:Femoral neck trabecular bone: loss with aging and role in preventing fracture. 1941 12

Hip fractures among the elderly are a worldwide problem. The objective of this study was (1) to confirm whether or not differences in bone strength are reflected in the proximal femur finite element (FE) model constructed from CT images of healthy subjects and osteoporosis patients, and (2) to investigate the effect of loading angle direction on bone fractures. The results from comparison of bone strength between the fracture group, fragile group (osteoporosis patients with no fracture after falling), and healthy group showed that differences in bone strength were definitely reflected in this FE model. Furthermore, the relationship between the loading direction and fracture load value was significant in all groups in the age-adjusted general linear model, and the model made from the trochanteric fracture patients was more sensitive to loading direction than those from cervical neck fracture. No significant differences were observed in the age-corrected comparison of DXA Neck BMD, Wards BMD, and total BMD in these two groups. The difference in the trochanteric BMD showed a trend of low bone density in the trochanteric fracture group. There is thus a possibility that the bone density at this location is implicated in the fragility under certain loading directions.
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PMID:The effect of impact direction on the fracture load of osteoporotic proximal femurs. 1966 19

Genome-wide association studies (GWAS) using high-density array of single-nucleotide polymorphisms (SNPs) offer an unbiased strategy to identify new candidate genes for osteoporosis. We used a subset of autosomal SNPs from the Affymetrix 500K+50K SNP GeneChip marker set to examine genetic linkage with multiple highly heritable osteoporosis-related traits, including BMD of the hip and spine, heel ultrasound (attenuation and speed of sound), and geometric indices of the hip, in two generations from the Framingham Osteoporosis Study. Variance component linkage analysis was performed using normalized residuals (adjusted for age, height, BMI, and estrogen status in women). Multipoint linkage analyses produced LOD scores > or =3.0 for BMD on chromosomes (chr.) 9 and 11 and for ultrasound speed of sound on chr. 5. Hip geometric traits were linked with higher LOD scores, such as with shaft width on chr. 4 (LOD=3.9) and chr. 16 (LOD=3.8) and with shaft section modulus on chr. 22 (LOD=4.0). LOD score > or =5.0 was obtained for femoral neck width on chr. 7. In conclusion, with an SNP-based linkage approach, we identified several novel potential QTLs and confirmed previously identified chromosomal regions linked to bone mass and geometry. Subsequent focus on the spectrum of genetic polymorphisms in these refined regions may contribute to finding variants predisposing to osteoporosis.
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PMID:Refined QTLs of osteoporosis-related traits by linkage analysis with genome-wide SNPs: Framingham SHARe. 2006 33

The effect of risedronate (2.5 mg once daily) on femoral strength was evaluated using Advanced Hip Assessment (AHA) for the first time in Japan. In total, 104 patients with primary osteoporosis and available data on bone mineral density (BMD; lumbar spine/proximal femur), urinary NTx (cross-linked N-telopeptides of type I collagen) and AHA-based parameters collected before and after 4 months of risedronate therapy were included in the analyses. Change and percentage change from baseline in these parameters were determined. Percentage change in femur strength index was 7.9 +/- 21.1% and 5.5 +/- 18.0% for the right and left femurs, respectively; both increases were statistically significant. Cross-sectional moment of inertia, cross-sectional area and mean neck width in the femoral neck region of interest also increased significantly in both femurs. Percentage change in lumbar spine BMD (L2 - L4) was 3.0 +/- 3.7%, and proximal femoral BMD was 1.1 +/- 3.1% and 0.7 +/- 3.2% in the right and left femurs, respectively, all showing a significant increase from baseline. Percentage change in urinary NTx was -41.5 +/- 30.5%, which was a significant decrease. Using AHA, this study showed that, in patients with primary osteoporosis, risedronate improved BMD and bone quality, thereby enhancing femoral strength as early as 4 months after treatment initiation.
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PMID:Evaluation of the effect of 4 months of risedronate therapy on femoral strength using femoral strength analysis tools. 2014 97


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