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

Hip fractures due to osteoporosis are accompanied with increased mortality and morbidity. Bone mineral density (BMD [g/cm(2)]) measured by dual-energy X-ray absorptiometry (DXA) is the most important risk factor. However, an overlap exists between results of fractured and nonfractured populations. Macro-architectural parameters of the femur are independent risk factors of fracture. They have been evaluated in two dimensions using X-ray films or DXA scans; therefore, they are highly dependent on patient positioning and interindividual anatomical variations. To overcome this problem, we have previously shown the possibility to reconstruct human femurs using two perpendicular DXA scans and to calculate 3-dimensional (3D) geometric parameters from these reconstructions by a method called 3-dimensional X-ray absorptiometry (3D-XA). The aim of this article is to assess whether the combination of areal BMD and 3D geometric parameters calculated from 3D-XA improves failure load prediction of human proximal femurs in stance phase configuration. Twelve femurs (11 women, 1 man; aged 88+/-9 yr; range: 72-103 yr) were included in this study. The BMD was measured using a Hologic Delphi-W device (Hologic, Waltham, MA) and 3D reconstruction of the femurs was done using two perpendicular DXA scans as previously published. The calculated 3D geometric parameters included femoral neck axis length (FNAL), mid-femoral neck cross-sectional area (mid-FN CSA), neck shaft angle (NSA), and femoral head diameter (FHD). Mechanical testing was performed using stance phase configuration, which resulted in subcapital fractures. The FHD was correlated to mid-FN CSA and FNAL (r=0.68 and 0.76, respectively; p<0.001). Failure load was correlated to age, FHD, NSA, and BMD measurements. Multiple regression analysis showed that femoral neck BMD, FHD, and mid-FN CSA gave the best statistical model for failure load prediction (r(2)=0.84; p<0.002). This is the first study suggesting that combining areal BMD to 3D geometric parameters obtained by 3D-XA improve failure load prediction in human femurs.
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PMID:Assessment of femoral neck strength by 3-dimensional X-ray absorptiometry. 1709 28

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.
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PMID:Structural trends in the aging proximal femur in Japanese postmenopausal women. 1751 85

Hip structural analysis (HSA) estimates geometrical and mechanical properties from hip dual-energy X-ray absorptiometry (DXA) images and is widely used in osteoporosis trials. This study compares HSA to volumetric quantitative computed tomography (QCT) measurements in the same population. A total of 121 women (mean age 58 yr, mean body mass index 27 kg/m2) participated. Each woman received a volumetric QCT scan and DXA scan of the left hip. QCT scans were analyzed with in-house software that directly computed geometric and mechanical parameters at the neck and trochanteric regions. DXA HSA was performed with an implementation by GE/Lunar. Pair-wise linear regression of HSA variables was conducted by method to site matched QCT variables for bone density, cross-sectional area, and cross-sectional moment of inertia (CSMI) of the femur neck. HSA correlated well with QCT (r2=0.67 for neck bone mineral density [BMD] and 0.5 for CSMI) and standard DXA at the neck (r2=0.82 for BMD). HSA and volumetric QCT compared favorably, which supports the validity of a projective technique such as DXA to derive geometrical properties of the proximal hip.
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PMID:Comparison of DXA hip structural analysis with volumetric QCT. 1926 99

Proximal femur fractures are of main concern for elderly and especially osteoporotic patients. Despite advanced implant modifications and surgical techniques, serious mechanical complication rates between 4-18% are found in conventional osteosyntheses of proximal femur fractures. Clinical complications such as the rotation of the femoral head and the cut-out phenomenon of the fracture fixation bolt are often diagnosed during post-operative treatments. Therefore, efforts in new intramedulary techniques focus on the load bearing characteristics of the implant by developing new geometries to improve the implant-tissue interface. The objective of this investigation was to analyse the osteosynthesis/femur head interaction of two commonly used osteosyntheses, one with a helical blade and the other one with a screw design under different loading conditions. For the comparative investigation the helical blade of the Proximal Femur Nail Antirotation was investigated versus the screw system of the Dynamic Hip Screw. After implantation in a femoral head the loads for rotational overwinding of the implants were analysed. Pull-out forces with suppressed rotation were investigated with analysis of the influence of the previous overwinding. All investigations were performed on human femoral heads taken of patients with average age of 70.3+/-11.8. The bone mineral densities of the human specimens were detected by QCT-scans (average BMD: 338.9+/- 61.3$\frac[\mathit[mg]][\mathit[cm];[3]]$) Prior to cadaveric testing the experimental set-up was validated and special influences were analysed by the use of synthetic foam blocks (Sawbone). The helical blade showed a significant higher torque for the rotation of the femoral head compared to the screw system. The pull-out forces of the blade were substantially lower than of the comparative screw. Taken together the helical blade showed a higher potential of rotational stability, but after a rotation the lower pull-out forces demonstrate a higher degree of damage to the femoral head.
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PMID:Biomechanical characterisation of osteosyntheses for proximal femur fractures: helical blade versus screw. 1837 8

Lead is stored in the skeleton and can serve as an endogenous source for many years. Lead may influence the risk of fracture, through direct effects on bone strength or indirectly by disturbing neuromuscular function and increasing the risk of falls. The objective of this analysis is to test the hypothesis that women with higher blood lead levels experience higher rates of falls and fracture. This was a prospective cohort study of 533 women 65-87 yr of age enrolled in the Study of Osteoporotic Fractures at two U.S. research centers (Baltimore, MD; Monongahela Valley, PA) from 1986 to 1988. Blood lead levels (in microg/dl) were measured in 1990-1991 by atomic absorption spectrophotometry and classified as "low" (<or=3; lower 15th percentile, referent); "medium" (4-7); or "high" (>or=8; upper 15th percentile). Total hip BMD was measured by DXA twice, 3.55 yr apart. Information on falls was collected every 4 mo for 4 yr. Incident nonspine fractures were identified and confirmed over 10 yr. Cox proportional hazards models were used to estimate the hazard ratio (HR) and 95% CI of fracture. Generalized estimating equations were used to calculate the incident rate ratio of falls (95% CI). The mean blood lead level was 5.3 +/- 2.3 (SD) microg/dl (range, 1-21 microg/dl). Baseline BMD was 7% lower in total hip and 5% lower in femoral neck in the highest compared with lowest blood lead group (p < 0.02). Hip bone loss tended to be greater in the high lead group, but differences were not significant. In multivariable adjusted models, women with high blood lead levels had an increased risk of nonspine fracture (HR = 2.50; 95% CI = 1.25, 5.03; p trend = 0.016) and higher risk of falls (incident rate ratio = 1.62; 95% CI = 1.07, 2.45; p trend = 0.014) compared with women with lowest lead level. Blood lead levels are associated with an increased risk of falls and fractures, extending the negative health consequences of lead to include osteoporotic fractures.
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PMID:Relationship of blood lead levels to incident nonspine fractures and falls in older women: the study of osteoporotic fractures. 1841 Feb 30

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


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