Assessment Of Hip Fracture Risk Research Articles

Assessment of hip fracture risk related to the structure

Bone strength is determined not only by BMD, but also by many other bone quality relating factors such as bone structure etc.. Hip fractures are the most serious fragile fractures, considering that controlling their risk factors will successfully prevent these fractures. Recently Hip structure (strength) analyses have become available during standard DXA measurements. Bending strength and stability of the bone can be determined by their obtained parameters such as section modulus, cross sectional area and buckling ratio. These parameters shift towards fragile by aging, especially remarkably reduce after 70 years. It has been reported that both anti-resorptive agents and anabolic PTH increase bone strength in different manner. Further progressed 3 dimensional femoral neck strength analysis using CT scanning are now under development.

The relationship between the OSTEODENT index and hip fracture risk assessment using FRAX

The OSTEODENT index is a predicted probability of osteoporosis derived from a combination of an automated analysis of a dental panoramic radiograph and clinical information. This index has been proposed as a suitable case-finding tool for identification of subjects with osteoporosis in primary dental care; however, no data exist on the relationship between OSTEODENT index and fracture risk. The aims of this study were to assess the relationship between the OSTEODENT index and hip fracture risk as determined by FRAX and to compare the performance of the OSTEODENT index and FRAX (without femoral BMD data), in determining the need for intervention as recommended in UK national treatment guidance. The study was a retrospective analysis of data from 339 female subjects (mean age 55.3 years), from 2 centers: Manchester (UK) and Leuven (Belgium). Clinical information and femoral neck BMD were available for FRAX, and dental panoramic radiographic data and clinical information were available to calculate the OSTEODENT index. Subjects were classified into "treat" or "lifestyle advice and reassurance" categories using the National Osteoporosis Guideline Group (NOGG) threshold. The OSTEODENT index result was significantly related to the 10-year probability of hip fracture derived from the reference standard FRAX tool (Rs = 0.67, P < .0001); 84 patients (24.8%) were allocated to the "treat" category on the basis of FRAX and the UK national guidance. Using this "treatment/no treatment" classification as the reference standard, ROC analysis showed no significant difference between areas under the curves for the OSTEODENT index (0.815) and the 10-year probability of hip fracture derived from the FRAX index without BMD (0.825) when used as tests for determining therapeutic intervention. The results suggest that the OSTEODENT index has value in prediction of hip fracture risk. Prospective trials are needed to confirm this finding and to examine the feasibility for its use in primary dental care.

Proximal hip geometry and hip fracture risk assessment in a Korean population

The association between proximal femoral geometry and hip fracture risk were investigated. The risk of intertrochanteric fractures increased 1.64-fold and 2.32-fold with 1 standard deviation (sd) increase of hip axis length and neck-shaft angle, respectively, while the risk of femur neck fracture 2.03-fold with 1 sd decrease in femoral head offset. The purpose of this study was to determine the association between proximal femoral geometry (PFG) and the risk of hip fracture in femur neck (FN) and intertrochanteric (IT) fractures in a Korean population. The study included 151 patients (57 patients with IT fractures, 43 patients with FN fractures, and 51 control patients). Data on BMD, PFG parameters (hip axis length [HAL], neck-shaft angle [NSA], neck length, femoral head offset, neck diameter, shaft diameter (SD), and demographics [age, gender, height, and body weight]) were collected. Descriptive statistics and odds ratios of PFG parameters corrected with demographic variables were obtained using logistic regressions. HAL (p = 0.046) and NSA (p = 0.003) were significantly greater in the patients with IT fracture than in the control patients, while neither parameter was significantly greater in patients with FN fractures than the control patients. The femoral head offset was significantly shorter in the patients with FN fractures (p = 0.003) compared with the control patients. In patients with IT fractures, the fracture risk increased 1.64-fold (p = 0.048) with a 1 sd increase of the HAL, while it increased 2.32-fold (p = 0.003) with a 1 sd increase of the NSA. In FN fractures, the fracture risk increased 2.03-fold (p = 0.012) with a 1 sd decrease in femoral head offset. Our study showed that some PFG parameters as well as BMD values predict hip fractures in a Korean population, and their evaluation may be useful in the understanding of the biomechanics of hip fractures.

Assessing Fracture Risk with DXA: Comparing 2008 to 1998 NOF Guidelines - The Influence of FRAX

Background: FRAX model offers the possibility to use either femoral neck BMD or BMI alone to evaluate fracture risk. Our aim was to evaluate the impact of using femoral neck BMD or BMI only on the fracture risk assessment based on this model. Materials: We use a retrospective analysis of medical records of 280 patients (262 women and 18 men, mean age of 63.4 years) who received treatment in National Program for Osteoporosis in Elias Hospital and C.I. Parhon Institute in Bucharest in 2008. Patients were selected based on the availability of femoral neck BMD and the lack of previous antiosteoporotic treatment. We calculated major osteoporotic fracture risk based on femoral neck BMD respective based on BMI alone for every patient. Same analysis was done for hip fracture risk. For treatment recommendation a cut off point of 20% was used for major osteoporotic fracture and 3% for hip fracture. Results: We found a significantly lower (p ! 0.001) risk fracture when we used BMI alone for both major osteoporotic fracture (mean 9.7 vs. 11.4) and hip fracture (mean 3.6 vs 4.8) risk evaluations. Using BMI alone comparing to femoral neck BMD to calculate major osteoporotic fracture risk, 17 patients (6%) were excluded from treatment recommendation and 2 (0.7%) were included. In the same manner, in the hip fracture risk evaluation, using BMI alone excluded 61 (21.8%) patients from treatment and 8 (2.8%) were included. Conclusion: Use of BMI alone significantly underestimated fracture risk for both major osteoporotic and hip fracture. Treatment recommendation based on hip fracture risk assessment was changed in almost 25% of the patients when using BMI alone, mostly trough exclusion from treatment (21.8%). It suggests that, for hip fracture risk assessment based on BMI alone could exclude from treatment a significant number of high risk patients.

BMD T-score discriminates trochanteric fractures from unfractured controls, whereas geometry discriminates cervical fracture cases from unfractured controls of similar BMD

The ability of bone mineral density (BMD) to discriminate cervical and trochanteric hip fractures was studied. Since the majority of fractures occur among people who are not diagnosed as having osteoporosis, we also examined this population to elucidate whether geometrical risk factors can yield additional information on hip fracture risk beside BMD. The study showed that the T-score criterion was able to discriminate fracture patients from controls in the cases of trochanteric fractures, whereas geometrical measures may discriminate cervical fracture cases in patients with T-score >-2.5. Low bone mineral density (BMD) is a well-established risk factor for hip fracture. However, majority of fractures occur among people not diagnosed as having osteoporosis. We studied the ability of BMD to discriminate cervical and trochanteric hip fractures. Furthermore, we examined whether geometrical measures can yield additional information on the assessment of hip fracture risk in the fracture cases in subjects with T-score >-2.5. Study group consisted of postmenopausal females with non-pathologic cervical (n = 39) or trochanteric (n = 18) hip fracture (mean age 74.2 years) and 40 age-matched controls. BMD was measured at femoral neck, and femoral neck axis length, femoral neck and shaft cortex thicknesses (FNC and FSC), and femoral neck-shaft angle (NSA) were measured from radiographs. BMD T-score threshold of -2.5 was able to discriminate trochanteric fractures from controls (p < 0.001). Seventeen out of 18 trochanteric fractures occurred in individuals with T-score <or=-2.5. However, the T-score criterion was not able to discriminate cervical fractures. Twenty of these fractures (51.3%) occurred in individuals with BMD in osteoporotic range and 19 (48.7%) in individuals with T-score >-2.5. Within these non-osteoporotic cervical fracture patients (N = 19) and non-osteoporotic controls (N = 35), 83.3% were classified correctly based on a model including NSA and FNC (p < 0.001), area under the receiver operating characteristics curve being 0.85 for the model, while it was only 0.56 for BMD alone. The study suggests that the risk of trochanteric fractures could be discriminated based on a BMD T-score <-2.5 criterion, whereas cervical fracture cases would remain under-diagnosed if solely using this criterion. Instead, geometrical risk factors are able to discriminate cervical fracture cases even among individuals with T-score >-2.5. For cervical and trochanteric fractures combined, BMD and geometric measures independently contributed to hip fracture discrimination. Our data support changing from T-score <-2.5 to a more comprehensive assessment of hip fracture etiology, in which fracture type is also taken into account. The findings need to be confirmed with a larger sample, preferably in a prospective study.

Analysis of hip geometry by clinical CT for the assessment of hip fracture risk in elderly Japanese women

Two case–control studies were designed to investigate the contribution of the geometry and bone mineral density (BMD) of the proximal femur to bone strength in Japanese elderly women. We also investigated whether clinical CT is useful to assess the risk of hip fracture. Subjects in the neck fracture study included 20 Japanese women with neck fracture (age: mean±SD; 80.1±4.5 years old) and 20 age-matched control women (79.2±2.6 years old). Subjects in the trochanteric fracture study included 16 Japanese women with trochanteric fracture (82.6±5.0 years old) and 16 age-matched control women (80.8±3.8 years old). CT examination of the proximal femur was performed between the date of admission and the date of surgery. The CT scanners used were an Aquillion 16 (Toshiba) and Somatom 64 (Siemens); the scanning conditions including spatial resolution and scanning energy were adjusted, and the same type of reference phantom containing hydroxyapatite was used. QCT PRO software (Mindways) was used to analyze data for BMD, geometry, and biomechanical parameters. Both the neck and trochanteric fracture cases had significantly lower total and cortical BMD, a significantly smaller cortical cross-sectional area (CSA), and a larger trabecular CSA. Both had significantly thinner cortex and smaller distance to center of bone mass, and women with trochanteric fracture had a significantly smaller cortical perimeter in the cross-sectional femoral neck. Women with neck fracture had a longer hip axis length (HAL) and women with trochanteric fracture had a significantly larger neck-shaft angle (NSA). Both groups had significantly lower cross-sectional moment of inertia (CSMI), and only women with neck fracture had a significantly higher buckling ratio (BR) compared to their respective controls. According to the multiple logistic regression analysis, women with neck fracture had a significantly longer HAL, lower CSMI, and higher BR, and women with trochanteric fracture had a significantly smaller cortical CSA of the femoral neck. We conclude that clinical CT may be useful for the assessment of the risk of neck and trochanteric fracture.

Association Analyses of RANKL/RANK/OPG Gene Polymorphisms with Femoral Neck Compression Strength Index Variation in Caucasians

Femoral neck compression strength index (fCSI), a novel phenotypic parameter that integrates bone density, bone size, and body size, has significant potential to improve hip fracture risk assessment. The genetic factors underlying variations in fCSI, however, remain largely unknown. Given the important roles of the receptor activator of the nuclear factor-kappaB ligand/receptor activator of the nuclear factor-kappaB/osteoprotegerin (RANKL/RANK/OPG) pathway in the regulation of bone remodeling, we tested the associations between RANKL/RANK/OPG polymorphisms and variations in fCSI as well as its components (femoral neck bone mineral density [fBMD], femoral neck width [FNW], and weight). This was accomplished with a sample comprising 1873 subjects from 405 Caucasian nuclear families. Of the 37 total SNPs studied in these three genes, 3 SNPs, namely, rs12585014, rs7988338, and rs2148073, of RANKL were significantly associated with fCSI (P = 0.0007, 0.0007, and 0.0005, respectively) after conservative Bonferroni correction. Moreover, the three SNPs were approximately in complete linkage disequilibrium. Haplotype-based association tests corroborated the single-SNP results since haplotype 1 of block 1 of the RANKL gene achieved an even more significant association with fCSI (P = 0.0003) than any of the individual SNPs. However, we did not detect any significant associations of these genes with fBMD, FNW, or weight. In summary, our findings suggest that the RANKL gene may play an important role in variation in fCSI, independent of fBMD and non-fBMD components.

Finite Element Analysis of Proximal Femur QCT Scans for the Assessment of Hip Fracture Risk In Older Men

Finite Element Analysis of Proximal Femur QCT Scans for the Assessment of Hip Fracture Risk In Older Men

Assessment of bone quality. Prospect of clinical assessment of bone quality

The privilege of technological progression permits clinical evaluation of structural properties of bone. Using clinical CT, three-dimensional measurement of bone mineral density and bone geometry in proximal femur is shown to be useful in the assessment of hip fracture risk. Microstructure is three-dimensionally visualized and measured by high resolution CT and MR, and their evaluation are demonstrated to be useful in the assessment of fracture risk and of efficacy of treatment.

Are Simple Tools Effective for Assessing Hip Fracture Risk

Given the morbidity and mortality associated with hip fracture, identifying at-risk individuals has been an important research focus (Journal Watch Women’s Health Aug 30 2007). Using data from more than 93,000 participants in the observational component of the Women’s Health Initiative (WHI), investigators developed a comprehensive model to predict 5-year risk for hip fracture in postmenopausal women. The algorithm was then validated based on information from more than …

Bone density and geometry in assessing hip fracture risk in post-menopausal women

We used femoral neck structural parameters (FNSPs), calculated from bone mineral density (BMD) measurements of the femoral neck by dual X-ray absorptiometry, to discriminate osteoporotic fractures of the proximal femur in post-menopausal women. We compared 1646 women without fracture and 429 women with hip fractures, including 273 with femoral neck (FN) and 156 with trochanter (TR) fractures. The association between the studied parameters and the fractures was modelled using multiple logistic regression, and included age, height and weight. Fracture-predicted probability (FPP) was also calculated for each predictor tested. Receiver operating characteristic (ROC) curve areas with their standard errors (SEs) were calculated for the fracture status, having the calculated FPP as a test variable. The areas were compared by the Hanley-McNeil test. Hip fracture had lower BMD, cross-sectional area (CSA), section modulus (SM) and cortical thickness (CT), and higher buckling ratio (BR), than controls. To the same extent as FN BMD, BR best predicted the risk for each fracture, showing ROC curve areas of 0.809 (SE 0.011) for hip fracture, 0.789 (SE 0.014) for FN fracture, and 0.848 (SE 0.016) for TR fracture. The association of BR with fracture risk did not differ from that of FN BMD, which has a ROC curve area of 0.801 (SE 0.011) for hip fracture, 0.778 (SE 0.014) for FN fracture, and 0.852 (SE 0.016) for TR fracture. Both FN BMD and BR predicted TR fracture significantly better than they did FN fracture. FNSPs, although interesting in understanding the biomechanics of bone fragility, do not appear to add diagnostic value to the simple measurement of BMD.

Contribution of Trochanteric Soft Tissues to Fall Force Estimates, the Factor of Risk, and Prediction of Hip Fracture Risk*

We compared trochanteric soft tissue thickness, femoral aBMD, and the ratio of fall force to femoral strength (i.e., factor of risk) in 21 postmenopausal women with incident hip fracture and 42 age-matched controls. Reduced trochanteric soft tissue thickness, low femoral aBMD, and increased ratio of fall force to femoral strength (i.e., factor of risk) were associated with increased risk of hip fracture. The contribution of trochanteric soft tissue thickness to hip fracture risk is incompletely understood. A biomechanical approach to assessing hip fracture risk that compares forces applied to the hip during a sideways fall to femoral strength may by improved by incorporating the force-attenuating effects of trochanteric soft tissues. We determined the relationship between femoral areal BMD (aBMD) and femoral failure load in 49 human cadaveric specimens, 53-99 yr of age. We compared femoral aBMD, trochanteric soft tissue thickness, and the ratio of fall forces to bone strength (i.e., the factor of risk for hip fracture, phi), before and after accounting for the force-attenuating properties of trochanteric soft tissue in 21 postmenopausal women with incident hip fracture and 42 age-matched controls. Femoral aBMD correlated strongly with femoral failure load (r2 = 0.73-0.83). Age, height, and weight did not differ; however, women with hip fracture had lower total femur aBMD (OR = 2.06; 95% CI, 1.19-3.56) and trochanteric soft tissue thickness (OR = 1.82; 95% CI, 1.01, 3.31). Incorporation of trochanteric soft tissue thickness measurements reduced the estimates of fall forces by approximately 50%. After accounting for force-attenuating properties of trochanteric soft tissue, the ratio of fall forces to femoral strength was 50% higher in cases than controls (0.92 +/- 0.44 versus 0.65 +/- 0.50, respectively; p = 0.04). It is possible to compute a biomechanically based estimate of hip fracture risk by combining estimates of femoral strength based on an empirical relationship between femoral aBMD and bone strength in cadaveric femora, along with estimates of loads applied to the hip during a sideways fall that account for thickness of trochanteric soft tissues. Our findings suggest that trochanteric soft tissue thickness may influence hip fracture risk by attenuating forces applied to the femur during a sideways fall and provide rationale for developing improved measurements of trochanteric soft tissue and for studying a larger cohort to determine whether trochanteric soft tissue thickness contributes to hip fracture risk independently of aBMD.

Association Between Prior Non-Spine Non-Hip Fractures or Prevalent Radiographic Vertebral Deformities Known to be at Least 10 Years Old and Incident Hip Fracture

In this large cohort of elderly women, prior non-spine non-hip fractures and radiographic vertebral deformities >10 years old were modestly associated with incident hip fracture, but the excess risks of hip fracture attributable to those prior fractures and deformities seem to wane over time. Whereas prior clinical fractures and prevalent radiographic vertebral deformities are well-documented predictors of incident hip fracture, the excess risks of incident fractures attributable to those prior fractures and deformities may decrease over time. Current guidelines regarding the assessment of fracture risk do not consider elapsed time since prior fracture or ascertainment of radiographic vertebral deformity. We ascertained self-reported history of prior clinical fractures and calcaneal and total hip bone BMD and performed lateral spine radiographs in a cohort of 9516 community-dwelling elderly women who had not had a prior hip fracture. We prospectively followed them to assess incident hip fracture. Prevalent radiographic vertebral deformities were identified at baseline using morphometry, and incident hip fractures were confirmed by review of radiographic reports during three follow-up periods (0-5, >5-10, and >10 years after baseline exam). Among women who survived for 10 or more years after the baseline exam without having had a hip fracture, a history of non-spine non-hip fracture since age 50 reported at the baseline study examination was associated with a 21% age- and calcaneal BMD-adjusted excess risk (hazard ratio [HR], 1.21; 95% CI, 1.01-1.45) for subsequent incident hip fracture. Baseline radiographic vertebral deformity was associated with a 41% age- and BMD-adjusted excess risk (HR, 1.41; 95% CI, 1.15-1.73) of hip fracture after 10 years of follow-up. In comparison, the age- and BMD-adjusted HRs of incident hip fracture during the first 5 years of follow-up associated with prior non-spine non-hip fractures reported at the baseline study exam and prevalent radiographic vertebral deformities were 1.70 (95% CI, 1.30-2.22) and 2.10 (95% CI, 1.58-2.78), respectively. Self-reported prior non-spine non-hip fractures and prevalent radiographic vertebral deformities known to be at least 10 years old are modestly associated with incident hip fracture. The association between these predictor fractures and subsequent hip fractures seems to wane with increased time after ascertainment of the predictor fracture. Hip fracture risk assessment strategies incorporating prior fracture history should also consider elapsed time since those prior fractures.

Prediction of Hip Fracture Risk by Quantitative Ultrasound in More Than 7000 Swiss Women ≥70 Years of Age: Comparison of Three Technologically Different Bone Ultrasound Devices in the SEMOF Study

To compare the prediction of hip fracture risk of several bone ultrasounds (QUS), 7062 Swiss women > or =70 years of age were measured with three QUSs (two of the heel, one of the phalanges). Heel QUSs were both predictive of hip fracture risk, whereas the phalanges QUS was not. As the number of hip fracture is expected to increase during these next decades, it is important to develop strategies to detect subjects at risk. Quantitative bone ultrasound (QUS), an ionizing radiation-free method, which is transportable, could be interesting for this purpose. The Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture Risk (SEMOF) study is a multicenter cohort study, which compared three QUSs for the assessment of hip fracture risk in a sample of 7609 elderly ambulatory women > or =70 years of age. Two QUSs measured the heel (Achilles+; GE-Lunar and Sahara; Hologic), and one measured the heel (DBM Sonic 1200; IGEA). The Cox proportional hazards regression was used to estimate the hazard of the first hip fracture, adjusted for age, BMI, and center, and the area under the ROC curves were calculated to compare the devices and their parameters. From the 7609 women who were included in the study, 7062 women 75.2 +/- 3.1 (SD) years of age were prospectively followed for 2.9 +/- 0.8 years. Eighty women reported a hip fracture. A decrease by 1 SD of the QUS variables corresponded to an increase of the hip fracture risk from 2.3 (95% CI, 1.7, 3.1) to 2.6 (95% CI, 1.9, 3.4) for the three variables of Achilles+ and from 2.2 (95% CI, 1.7, 3.0) to 2.4 (95% CI, 1.8, 3.2) for the three variables of Sahara. Risk gradients did not differ significantly among the variables of the two heel QUS devices. On the other hand, the phalanges QUS (DBM Sonic 1200) was not predictive of hip fracture risk, with an adjusted hazard risk of 1.2 (95% CI, 0.9, 1.5), even after reanalysis of the digitalized data and using different cut-off levels (1700 or 1570 m/s). In this elderly women population, heel QUS devices were both predictive of hip fracture risk, whereas the phalanges QUS device was not.

Cognitive Status, Body Mass Index, and Hip Fracture in Older Hispanic Adults

To examine the interactive effect of cognition and body weight on hip fracture. A 7-year (1993-2000) prospective cohort study. Five southwestern states (Texas, New Mexico, Arizona, Colorado, and California). Noninstitutionalized Mexican Americans (N=2,653) aged 65 and older and free of hip fracture at baseline interview. Incidence of hip fracture at 2-, 5-, and 7-year follow-up interviews. Body weight and cognition were measured using body mass index (BMI) and Mini-Mental State Examination score, respectively. Covariates included sociodemographics, self-reported medical conditions, visual acuity, and Short Physical Performance Battery. A significant interaction between BMI and hip fracture was found in persons with cognitive impairment (hazard ratio =0.91, 95% confidence interval=0.85-0.98; P=.02), after adjusting for covariates. In the lowest BMI category, the hip fracture rate in cognitively impaired subjects was more than four times the hip fracture rate for subjects who were not cognitively impaired with the same BMI (34.6% vs 8.7%). Hip fracture rates in the highest BMI category were similar in persons with and without cognitive impairment (9.3% vs 6.1%). Low cognitive function increased the conditional association between BMI and hip fracture in older Mexican Americans. The relationship between BMI and cognition is potentially important in identifying persons at risk for hip fracture and supports the need to include cognitive and anthropometric measures in the assessment of hip fracture risk into osteoporosis screening programs.

Volumetric bone density at the femoral neck as a common measure of hip fracture risk for men and women.

Measurements of bone density using dual-energy x-ray absorptiometry are generally based on the areal projection, which incompletely accounts for size. The larger areal bone density in older men compared with older women is primarily due to their larger bone size, conferring a biomechanical advantage that may be a major factor contributing to lower hip fracture rates. The aim of this study was to evaluate estimated volumetric bone density at the hip in men and women with and without fractures to better determine the role of estimated volumetric density vs. size in hip fracture risk. This prospective population-based study compared 852 women and 635 men without fractures with 73 women and 23 men with hip fractures. As expected, areal bone mineral density (BMD) and cross-sectional area were lower in women than men, and areal bone density was lower in those with hip fractures compared with nonfracture subjects. However, estimated volumetric BMD was the only parameter, apart from age, that was the same in women and men both without hip fractures (0.31 +/- 0.06 and 0.31 +/- 0.06 g/cm3, respectively) and with hip fractures (0.25 +/- 0.04 and 0.26 +/- 0.04 g/cm3, respectively). Using the World Health Organization 2.5 SD cut-off for osteoporosis for hip fracture prediction, estimated volumetric BMD was more sensitive than areal BMD in men (70 vs. 43%; P = 0.04) and similar to that in women, in whom sensitivity was similar for both areal (73%) and estimated volumetric (78%) BMD cut-offs. Thus, men and women have hip fractures at the same estimated femoral neck volumetric BMD, which is largely independent of the size artifact inherent in areal BMD. This aspect of estimated femoral neck volumetric BMD suggests that it can provide a single measure that could be used in men and women. It needs further exploration for a role in assessment of hip fracture risk across the sexes and particularly in men.

Hip fracture risk assessment using composite indices of femoral neck strength: the Rancho Bernardo study.

The objective of this work was to examine the prediction of incident hip fracture risk by composite indices of femoral neck strength, constructed from dual X-ray absorptiometry (DXA) scans of the hip. These indices integrate femoral neck size and body size with bone density, and reflect the structure's ability to withstand axial compressive forces and bending forces, and the ability to absorb energy in an impact. We studied a prospective cohort of community-dwelling women, 55 years or older at baseline, average age 72 years, that was established in 1988, with follow-up until 1998. Higher baseline values of each composite strength index were associated with lower risk of incident hip fracture in this cohort. After adjusting for age and body mass index, relative risks associated with each standard deviation increment in the composite indices were 0.39 for compression strength (95% confidence interval 0.25-0.60), 0.43 for bending strength (95% confidence interval 0.27-0.70), and 0.34 for impact strength (95% confidence interval 0.20-0.58). Larger bone size relative to body size was associated with lower risk of incident hip fracture. After adjusting for age, body mass index, and bone density, each standard deviation increment in femoral neck width normalized by body weight was associated with incident hip fracture relative risk of 0.38 (95% confidence interval 0.20-0.70). Our results suggest that composite indices of femoral neck strength, constructed from DXA measurements, have the potential to improve hip fracture risk assessment. This needs further exploration in larger cohorts and in different population sub-groups.

Radial bending breaking resistance derived by densitometric evaluation predicts femoral neck fracture.

Bone mineral density (BMD) measurement by hip dual-energy X-ray absorptiometry (DXA) is considered the best predictor of osteoporotic fracture risk. BMD takes into account only in part the bone cross-sectional area that is an important determinant of both bone compression strength and of bending breaking resistance. From DXA measurements of proximal radius (Osteoplan, NIM, Verona, Italy) we obtained the projected outer diameter (D) and the mean diameter of the medulla (d), by an algorithm based on the assumption of a constant cortical volumetric density of 1050 g/cm3. The algorithm was validated by the good correlation found (r = 0.8) between calculated d and that actually measured by peripheral quantitative tomography (pQCT; XCT 960, Stratec, Unitrem, Italy) at the same radial site. The D and d values were used to calculate a bending breaking resistance index (BBRI) that is a component of the cross-sectional moment of inertia. The BBRI measured in 5460 women aged 35-89 years, was stable up to the age of 65-70 years and rapidly declined thereafter by 0.7% per year. This profile appears to be due to the fact that the increase in medullary area is compensated in terms of mechanical resistance by enlargement of cross-sectional area. In 68 women with either previous femoral neck (n = 41) or pertrochanteric fracture (n = 27) DXA measurements at proximal and ultradistal radius, lumbar spine and femoral neck were obtained together with the evaluation of proximal radius BBRI. The diagnostic accuracy of BBRI was somewhat comparable to that of spine and femoral neck BMD and significantly superior to that of ultradistal and proximal radius BMD, from which it was derived. Despite the obvious limitation of the cross-sectional nature of this study, our results indicate that a simple re-elaboration of the data obtained by peripheral radial densitometry may achieve diagnostic accuracy for hip fracture risk assessment only marginally lower than that of the direct measure of the BMD of the femoral neck. They also give additional support to the view that bone geometry, particularly for compact skeletal segments, is a determinant of its strength at least as important as bone density.

Added value of bone mineral density in hip fracture risk scores

Hip fractures constitute a major health problem. For effective prevention, high-risk groups need to be identified. The objective here was to develop hip fracture risk scores while assessing the added value of bone mineral density relative to more conventional risk indicators. We prospectively followed during 4 years a cohort of 5208 persons (2193 men) aged 55 years and over from the Rotterdam Study, a population-based cohort study conducted in the Netherlands. Risk scores for hip fracture were constructed using several conventional risk indicators requiring interview and anthropometry only, and bone mineral density. During follow-up, 50 persons (14 men) suffered hip fracture. Hip fracture risk was independently determined by age, gender, height, the use of a walking aid, cigarette smoking, and either bone mineral density or weight. We developed two risk scores, with and without bone mineral density. The observed 4-year risk ranged from 3/3389 (0.1%) to 17/169 (10.1%) for the lowest and highest category of the score including bone mineral density, respectively. For the score without bone mineral density, these risks were 8/3117 (0.3%) and 16/144 (11.1%), respectively. The area under the receiver operating characteristic curve indicating discriminatory power was 0.88 for the risk score including, and 0.83 for the score excluding, bone mineral density ( p for difference = 0.04). In conclusion, risk scores with and without bone mineral density measurement can be used for hip fracture risk assessment in elderly persons. While the score with bone mineral density has a modestly better performance, the score requiring interview and anthropometry only may be especially useful in primary care settings.

Prediction of the strength of the elderly proximal femur by bone mineral density and quantitative ultrasound measurements of the heel and tibia

Quantitative ultrasound (QUS) of the heel and tibia have recently been approved in the United States for diagnostic evaluation of low bone mass. The goal of this study was to use human cadaveric specimens to compare correlations among: a) strength of the proximal femur; b) bone mineral density of the femur, tibia, and heel; and c) QUS of the tibia and heel. We obtained 26 proximal femurs and intact lower limbs from 16 female and 10 male cadavers, with a mean age of 81 ± 12 years. Bone mineral density (BMD, g/cm 2) of the proximal femur and tibia were assessed using dual-energy x-ray absorptiometry, and BMD (g/cm) of the heel was measured using single-energy x-ray absorptiometry. Ultrasound velocity at the mid-tibia was determined using a contact, gel-coupled ultrasound device. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the heel were determined using a transmission ultrasound device with water-based coupling. The femurs were tested to failure in a configuration designed to simulate a fall to the side with impact to the greater trochanter. As in previous studies, the strength of the proximal femur was very strongly correlated with femoral BMD and heel BMD (r 2 = 0.78–0.92, p < 0.0001 for all). BUA and SOS of the heel were also strongly correlated to femoral strength (r 2 = 0.70 and 0.67, respectively, p < 0.0001 for both), whereas tibia SOS was only weakly correlated (r 2 = 0.19, p = 0.03). The average coefficient of variation for triplicate tibial SOS measurements was 0.50%. This study indicates that, although tibial SOS measurements are precise, they are not strongly correlated with femoral BMD or strength. In contrast, heel QUS measurements are strongly correlated with the strength of the proximal femur. These findings imply that tibial SOS may be of limited use for assessing hip fracture risk. Prospective fracture risk data are needed to define further the clinical utility of tibia ultrasound measurements.