Prediction of incident hip fracture by femoral neck bone mineral density and neck-shaft angle: a 5-year longitudinal study in post-menopausal females.

OBJECTIVE: To compare hip fracture incidence in post-menopausal females who were differently stratified for the fracture risk according to bone mineral density and proximal femur geometry. METHODS: In a 5 year follow-up study, the hip fracture incidence in 729 post-menopausal females (45 of whom suffered from incident hip fracture) was assessed and compared. Forward logistic regression was used to select independent predictors of hip fracture risk, including age, age at menopause, height, weight, femoral neck bone mineral density (FNBMD), neck-shaft angle (NSA), hip axis length, femoral neck diameter and femoral shaft diameter as covariates. Fracture incidence was then calculated for the categories of young/old age, high/low FNBMD and wide/narrow NSA, which were obtained by dichotomising each hip fracture independent predictor at the value best separating females with and without a hip fracture. RESULTS: The hip fracture incidence of the whole cohort was significantly higher in females with a wide NSA (8.52%) than in those with a narrow NSA (3.51%). The combination of wide NSA and low FNBMD had the highest hip fracture incidence in the whole cohort (17.61%) and each age category. The combinations of narrow/wide NSA with low/high FNBMD, respectively, gave a significantly higher fracture incidence in older than in younger women, whereas women with a combined wide NSA and low FNBMD had no significantly different fracture incidence in young (14.60%) or old age (21.62%). CONCLUSION: Our study showed that NSA is effective at predicting the hip fracture risk and that the detection in early post-menopause of a wide NSA together with a low FNBMD should identify females at high probability of incident hip fracture.

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.

Differences in proximal femur geometry distinguish vertebral from femoral neck fractures in osteoporotic women.

Bone mineral density (BMD) is generally used to predict the risk of fracture in osteoporotic subjects. However, femoral neck BMD and spine BMD have been reported not to be significantly different among patients with hip or vertebral fractures, suggesting that other risk factors are needed to determine the different fracture types. Proximal femur geometry (PFG) parameters, such as hip axis length (HAL), femoral neck-shaft angle (NSA) and femoral neck diameter (FND) have also been shown to predict the risk of hip fracture. These parameters are statistically different in spine fractures compared with both types of hip fractures (trochanteric and femoral neck) when considered together. We wanted to assess the difference in these parameters by comparing spine fractures with a homogeneous group of hip fractures, i.e. femoral neck fractures. 807 post-menopausal women were divided into three groups; those with vertebral fractures (182), those with femoral neck fractures (134) and a control group without fractures (491). Dual X-ray absorptiometry (DXA) scans of the spine and hip were carried out to measure BMD and define the PFG parameters of the hip. Data were statistically analysed. In agreement with other authors, we found that women with femoral neck fractures had longer HAL, wider FND and larger NSA than controls, whereas there were no statistically significant differences in PFG between women with spine fractures and controls. Logistic regression showed HAL and NSA could predict the risk of femoral neck but not vertebral fracture. These data indicate specificity of some PFG parameters for hip fracture risk.

L-arginine and L-lysine stimulation on cultured human osteoblasts.

Essential amino acids, such as L-Arginine (Arg) and L-Lysine (Lys), are involved in bone metabolism and growth. Our previous studies analyzed the effect of these amino acids on rat osteoblast cultures and in experimental animals. In this study, we evaluated the effect of L-Arg and L-Lys on cultured human osteoblasts. Primary human osteoblast cultures were divided into four groups: the Arg Group received 0.625 mg/ml per day of Arg, the Lys Group 0.587 mg/ml per day of Lys, the Arg-Lys Group received both amino acids, whereas the Control Group was sham-treated. After 7 days, the following parameters were tested in all groups: alkaline phosphatase (ALP), nitric oxide (NO), calcium (Ca), phosphorus (P), osteocalcin (OC), type I collagen (PICP), interleukin-6 (IL-6), transforming growth factor-beta 1 (TGF-beta 1) on culture supernatant, platelet derived growth factor (PDGF), insulin-like growth factor-I (IGF-I), and MTT proliferation test on cells. Arg administration significantly increased ALP, NO, PICP and IGF-I production and reduced the level of IL-6. Lys administration over the same time interval mainly affected cell proliferation, as evidenced by the MTT test and immunostaining for PDGF. The same positive effects evidenced by the single administrations of the two amino acids resulted from their simultaneous administration. However, synergism could be demonstrated only for the decrease in the level of IL-6. Arg and Lys show a positive effect on human osteoblasts, which is related partly to the production of those factors required for matrix synthesis, and partly to the direct or mediated activation of cell proliferation.

Brucella spondylitis with paravertebral abscess due to Brucella melitensis infection: a case report.

This report describes the case of a 45-year-old woman with a 5-month history of fever, generalized malaise, myalgia, lower back pain and difficulty in walking. Serodiagnosis for brucella, carried out at the onset of symptoms 5 months previously, was negative. When the patient was admitted to our hospital there was contracture of the paraspinal muscles but no peripheral nerve damage. Laboratory tests showed positive agglutination for Brucella and an increase in the rate of dilution from 1/160 to 1/640 over 2 weeks. Radiographs and a computed tomography scan of the spine revealed bone erosion in the posterior borders of the L4-L5 vertebral end plates and a soft tissue mass surrounding the interposed disc and protruding into the spinal canal. Magnetic resonance imaging confirmed the presence of a paraspinal abscess around the affected disc and tissue edema. Culture tests of the blood and abscess tissue, taken by biopsy, were negative. Rifampicin treatment (600 mg daily), combined with a bust cast to immobilize the spine, led to clinical healing without the need for surgery. Because onset symptoms are nonspecific and insidious, in nonrisk subjects a diagnosis of brucellosis may sometimes be suspected only if there are local symptoms. The phenomenon of the absence of positivity in patients with a high antibody titer should also be considered Cases such as that described herein demonstrate the need for culture tests and serodiagnosis, even in nonrisk patients with persistent fever and arthralgia, to prevent the later complications of brucellosis.

The femoral distal epiphysis of ovariectomized rats as a site for studies on osteoporosis: structural and mechanical evaluations.

OBJECTIVE: To investigate in detail the mechanical and structural characteristics of cancellous bone from the femoral distal epiphysis of normal and ovariectomized rats, and to provide reference values in order to improve experimental research on osteoporosis by characterising an alternative and complementary anatomic site. METHODS: 40 female Sprague-Dawley rats (10 months old) were randomly divided into 4 groups of 10 each: baseline, ovariectomized (Ovx), sham-operated (Sham-Ovx) and sham-aged (Sham-Aged). Baseline animals were sacrificed at the beginning of the study. Ovx and Sham-Ovx animals were sacrificed 16 weeks after surgery, whereas Shamaged rats were killed when aged 14 months. Femurs were excised and densitometric, ultrasonographic, mechanical and histomorphometric analyses were performed. RESULTS: When comparing the Ovx group with the others, ultrasonographic and densitometric measurements showed significant decreases (p < 0.0005) amounting to 3-5% in the amplitude dependent speed of sound (AD-SOS) and 13-20% in the BMD, respectively. Significant decreases were also seen in the femoral condyle Max. Load (28-31%; p < 0.0005) and Elastic Modulus (19-25%; p < 0.005) in the Ovx group in comparison with the Sham-Ovx and Sham-Aged groups. Histomorphometric analysis showed a significant cancellous bone loss (p < 0.0005). Densitometric (p < 0.01), histomorphometric (p < 0.01) and mechanical (p < 0.05) parameters were correlated with AD-SOS. Among the histomorphometric parameters, stepwise regression analysis showed that the trabecular bone volume (BV/TV) and Max. Load correctly predicted AD-SOS (p < 0.0005) and BMD (p < 0.0005). CONCLUSION: The data from this study characterize osteopenia occurring in the rat distalfemur 16 weeks after ovariectomy and provide methodology and reference values forfurther investigations on osteoporosis and bone-implant osteointegration in osteopenic bone.

Proximal femur geometry to detect and distinguish femoral neck fractures from trochanteric fractures in postmenopausal women.

Some proximal femur geometry (PFG) parameters, measured by dual-energy X-ray absorptiometry (DXA), have been reported to discriminate subjects with hip fracture. Relatively few studies have tested their ability to discriminate femoral neck fractures from those of the trochanter. To this end we performed a cross-sectional study in a population of 547 menopausal women over 69 years of age with femoral neck fractures (n = 88), trochanteric fractures (n = 93) or controls (n = 366). Hip axis length (HAL), neck-shaft angle (NSA), femoral neck diameter (FND) and femoral shaft diameter (FSD) were measured by DXA, as well as the bone mineral density (BMD) of the nonfractured hip at the femoral neck, trochanter and Ward's triangle. In fractured subjects, BMD was lower at each measurement site. HAL was longer and NSA wider in those with femoral neck fractures. With logistic regression the age-adjusted odds ratio (OR) for a 1 standard deviation (SD) decrease in BMD was significantly associated at each measurement site with femoral neck fracture (femoral neck BMD: OR 1.9, 95% confidence interval (95% CI): 1.4-2.5; trochanter BMD: OR 1.6, 95% CI 1.2-2.0; Ward's triangle BMD: OR 1.7, 95% CI 1.3-2.2) and trochanteric fracture (femoral neck BMD: OR 2.6, 95% CI 1.9-3.6; trochanter BMD: OR 3.0, 95% CI 2.2-4.1; Ward's triangle BMD: OR 1.8, 95% CI 1.4-2.3). Age-adjusted OR for 1 SD increases in NSA (OR 2.2, 95% CI 1.7-2.8) and HAL (OR 1.3, 95% CI 1.1-1.6) was significantly associated with the fracture risk only for femoral neck fracture. In the best predictive model the strongest predictors were site-matched BMD for both fracture types and NSA for neck fracture. Trochanteric BMD had the greatest area (0.78, standard error (SE) 0.02) under the receiver operating characteristic curve in trochanteric fractures, whereas for NSA (0.72, SE 0.03) this area was greatest in femoral neck fractures. These results confirm the association of BMD with proximal femur fracture and support the evidence that PFG plays a significant role only in neck fracture prediction, since NSA is the best predictive parameter among those tested.

Comparison of calcitonin, alendronate and fluorophosphate effects on ovariectomized rat bone.

The effects of calcitonin, alendronate and fluorophosphate preventive treatment on ovariectomized rat femur were studied by comparing densitometric, mechanical, mineralogical and histomorphometric data. Sixty retired breeder female Sprague-Dawley rats, aged 10 months, were randomly divided into six groups. A group (baseline) was euthanized at the beginning of the study as a baseline group; four groups were ovariectomized and one was sham-operated (sham) and considered as a sham-aged group. A group of ovariectomized rats was used as a sham-therapy control (OVX) and received only deionized drinking water, while the other three received: a) salmon calcitonin (SCN) at a dose of 2 IU/kg/d s.c. (OVX + SCN); b) alendronate sodium salt (ALN) at a dose of 6 microg/kg/d administered by gavage (OVX + ALN); and c) L-glutamine monofluorophosphate (G-MFP) and calcium at a rate of 1:30 F/Ca at a dose of 0.21 mg F/6.30 mg Ca per kg/d by gavage (OVX + MFP). Significant increases (P < 0.05) of about 15 and 27% in femoral proximal epiphysis bone mineral density (BMD) of the OVX + ALN group were observed versus healthy groups and the OVX group, respectively. The OVX + ALN group also showed significant increases in femoral mid-diaphysis BMD when compared to OVX (18%, P < 0.001), OVX + SCN (14%, P < 0.05) and OVX + MFP (18%, P < 0.001) groups. In the OVX + MFP group, the three-point bending test demonstrated significant increases (P < 0.05) in maximal load of 21 and 22% when compared to the OVX and OVX + SCN groups, respectively. Also, stiffness data showed significant increases of the OVX + MFP (17%) and sham (14%) groups in comparison with the OVX group. A decrease in Mg (42%, P < 0.05), and increases in Ca (15%, P < 0.0001) and PO4 (8%, P < 0.005) content were found by comparing OVX + MFP and OVX groups. Trabecular bone volume results showed significant increases by comparing OVX + ALN and OVX groups (12.20%, P < 0.0005), as well as control groups. Tested agents were able to reduce the bone loss due to estrogen deficiency, but this did not always produce an increase in strength of the treated bone. Alendronate treatment prevented a decrease in bone mineral density and maintained bone mechanical properties after ovariectomy without impairment of bone mineralization in aged rats.

Effect of intramuscular clodronate on bone mass and metabolism in osteoporotic women.

Bisphosphonates have significantly improved the treatment of postmenopausal osteoporosis. However, when administered orally, gastric intolerance is their main adverse effect. This makes patients reluctant to undergo treatment. As an alternative, intramuscular (i.m.) administration may be more acceptable to patients undergoing long-term treatment. Since clodronate has been easily available in Italy for many years, we carried out this study to evaluate its effect on bone mineral density (BMD) in 36 osteoporotic postmenopausal women who were intolerant to oral administration of bisphosphonates. Patients received 100 mg of clodronate i.m. every 10 days together with 500 mg/day of calcium orally for 2 years. A control group of 32 women received only oral calcium at the same dose and for the same length of time. In the control group a progressive but not statistically significant decrease in BMD was observed in the spine and femoral neck over the 2-year follow-up. In contrast, patients treated with clodronate had a statistically significant increase in BMD in the spine at the first yearly check-up (+2.63%) and a further but not statistically significant increase during the second year of treatment (+0.59%). The increase in BMD at the femoral neck was not statistically significant during the first and second years of treatment, being 1.21% and 0.37% respectively. In the women treated with clodronate, hydroxyproline was significantly suppressed. All the patients reported local pain at the injection site. This led 11.11% of the subjects to withdraw from treatment.

Bone mineral density and bone loss measured at the radius to predict the risk of nonspinal osteoporotic fracture.

Low bone mineral density (BMD) and, probably, the rate of bone loss (RBL) are associated with the risk of osteoporotic fractures. To estimate the risk of nonspinal fracture in osteoporotic women, we measured BMD and RBL in a prospective study (average follow-up, 5.38 years) in 656 postmenopausal women. The women were considered in three groups: group A (whole population), group B (women under the age of 65 years) and group C (women over the age of 65 years). At the beginning of the study, BMD was measured at the distal radius (DR) and at the proximal radius (PR) using a single-energy densitometer. BMD measurements made 2 years previously in the same patients were used to calculate RBL. Then patients were checked annually for nonspine fracture due to minor trauma. During follow-up, 121 nonspinal fractures were detected. Women with fractures were older and had lower BMD. With the Cox regression, age-corrected BMD at both DR and PR predicts fracture risk in groups A and B but not in group C. After correction for potential confounders, DR still predicts fractures in groups A and B whereas PR predicts fractures only in group B. In group C, only the RBL at the PR was predictive of the fracture risk as well as in the other two groups. Specific types of fractures are predictable in the whole population at the wrist. In conclusion, radial BMD predicts the risk of nonspine fractures except in women over the age of 65 years. The RBL at the PR is an effective predictor of fracture risk also in women over the age of 65 years.

Fracture prediction for the femoral neck using finite element models.

Fracture of the femoral neck is an important clinical, social and economic topic. Prediction in subjects who are at risk for this type of fracture has been the object of numerous studies. Nonetheless, the methods of classification based on densitometric indicators alone have shown poor accuracy. It is the purpose of this study to propose a method to obtain an estimate of the resistance of the proximal femur, and to improve accuracy in prediction in subjects who are at risk for fracture. Based on the densitometric dataset alone, a bidimensional finite element model was developed that takes into account the distribution of density together with the femoral anatomy and the typical conditions of trauma. The model was applied to a group of preliminary osteoporotic patients. The statistical classification showed an increase in accuracy by 13%, as compared to a classification based on densitometric indicators alone.

Comparison of logistic and Bayesian classifiers for evaluating the risk of femoral neck fracture in osteoporotic patients.

Femoral neck fracture prediction is an important social and economic issue. The research compares two statistical methods for the classification of patients at risk for femoral neck fracture: multiple logistic regression and Bayes linear classifier. The two approaches are evaluated for their ability to separate femoral neck fractured patients from osteoporotic controls. In total, 272 Italian women are studied. Densitometric and geometric measurements are obtained from the proximal femur by dual energy X-ray absorptiometry. The performances of the two methods are evaluated by accuracy in the classification and receiver operating characteristic curves. The Bayes classifier achieves an accuracy approximately 1% higher than that of the multiple logistic regression. However, the performances of the two methods, evaluated by the area under the curves, are not statistically different. The study demonstrates that the Bayes linear classifier can be a valid alternative to multiple logistic regression in the classification of osteoporotic patients.

Quantitative ultrasound and bone densitometry to evaluate the risk of nonspine fractures: a prospective study.

The ability of quantitative ultrasound (QUS) to estimate the risk of osteoporotic fractures was evaluated in a prospective study over a mean time of 5.47 years in 254 postmenopausal women (mean age 58.06+/-7.67 years). Baseline measurements of ultrasound transmission velocity (UTV) and bone mineral density (BMD) were taken at the distal radius (DR). UTV was also measured at the patella (P). Fifty nonspine fractures due to minor trauma were detected during annual check-ups with an incidence of 3.59/year. Fractures occurred in older women with a lower BMD and QUS. Using Cox regression analysis the relative risk (RR) per 1 standard deviation (SD) decrease in the unadjusted QUS and BMD measurements was: BMD-DR = 3.56, 95% confidence interval (CI) 1.57-8.09; 95% CI 2.08-9.68. The relationship between BMD and QUS variables and fracture risk persisted after adjusting for potential confounders apart from previous fractures, giving the following RR: BMD-DR = 2.99, 95% CI 1.06-8.41; UTV-DR = 3.69, 95% CI 1.18-11.49; UTV-P = 3.89, 95% CI 1.53-9.90. Correcting also for previous fractures, only UTV-P remained an effective predictor of fracture risk even after QUS measurement correction for BMD. Wrist fractures were best related to BMD-DR (RR 7.33, 95% CI 1.43-37.50) and UTV-DR (RR 10.94, 95% CI 1.10-108.45), while hip and ankle fractures were significantly associated only with UTV-P (hip: RR 32.14, 95% CI 1.83-562.80; ankle: RR 17.60, 95% CI 1.78-173.79). The combined use of BMD and QUS is a better predictor of fracture risk than either technique used separately. Comparison of the areas under the receiver operating characteristic (ROC) curves did not show differences in the ability of BMD and QUS to correctly distinguish fractures. In conclusion, QUS predicts fracture risk in osteoporotic women at least as well as BMD. UTV-DR and BMD-DR are good predictors of wrist fractures, while UTV-P is strongly related to hip and ankle fractures. QUS and BMD combined improve the diagnostic ability of each technique individually.

Discriminant capacity of quantitative ultrasound versus dual X-ray absorptiometry to determine cancellous bone loss in ovariectomized rats.

The capacity of dual x-ray absorptiometry and quantitative ultrasound to discriminate bone loss and to predict the mechanical and microarchitectural properties of cancellous bone in an animal model of osteopenia was evaluated. Thirty-five female Sprague-Dawley rats (10 months old) were randomized into three groups: baseline group, 10 rats killed at the beginning of the study; ovx group, 15 rats ovariectomized; and sham group, 10 rats sham operated. At the beginning and end of the study, all the animals underwent osteosonography to record the proximal tail (C3 vertebra) bone speed of sound. Sixteen weeks after surgery, the animals were euthanized and the L5-6 lumbar vertebrae of each rat were excised for densitometric, biomechanical (compression test), and histomorphometric studies. Significant differences were found among the groups for final speed of sound (p = 0.01). The L5 bone mineral density of the ovx group decreased by 12.1% (p = 0.049) and 12.6% (p = 0.035) compared, respectively, with baseline and sham groups. The biomechanical parameters of the ovx group decreased by 15-47% compared with the other groups, showing significant differences between the ovx and sham groups both for maximal stress (p = 0.026) and elastic modulus (p = 0.013). Histomorphometric parameters of the ovx group showed significant decreases in comparison with other groups. Logistic regression analysis showed that dual X-ray absorptiometry and quantitative ultrasound discriminate ovariectomized and healthy rats with a similar capacity, classifying correctly all rats used in the model in a range of 61-70%. This similar capacity seems to derive from two different capacities to detect bone changes. Dual X-ray absorptiometry, depending on bone mineralization and density, is able to detect modifications in bone stiffness and strength, confirmed also by the correlation with biomechanical data. On the contrary, quantitative ultrasound seems to depend more on cancellous bone microarchitecural changes because it is correlated to histomorphometric parameters.

Calcitriol and alendronate combination treatment in menopausal women with low bone mass.

Serum calcitriol levels decrease with advancing age in relation to reduced dietary intake or poor intestinal absorption of vitamin D. These decreased levels affect the development of senile osteopenia, which can be effectively prevented by the administration of alendronate and calcium. To evaluate the effect of a combined treatment with alendronate and calcitriol on bone mineral density (BMD), we followed 152 osteopenic postmenopausal women, aged 55-75 years, for 9 months. They were divided into three groups. The first group was treated every other day with 0.25 microgram of synthetic 1,25-dihydroxyvitamin D3 plus 10 mg alendronate. The second group received the same dose of alendronate plus calcium (500 mg/day). The third group received only calcium (500 mg/day). BMD measurements were made at the level of the lumbar spine and the femoral neck. At the beginning and at the end of the period of treatment the same biochemical analyses of bone metabolism were made. There were no significant differences in the baseline values of the three groups in the biological parameters. Alendronate plus calcium treatment led to a significant reduction in total alkaline phosphatase and hydroxy prolinuria as well as to a significant increase in lumbar and femoral bone density. The same changes were observed in the group treated with alendronate plus calcitriol except that femoral BMD did not significantly improve. These results show that continuous treatment for 9 months with calcitriol or calcium in combination with alendronate significantly increases both vertebral and femoral neck density (from 3.8% to 4.5% and from 0.61% to 2.36% respectively) in osteopenic postmenopausal women. The effects of both combinations on bone mass are clearly greater than those achieved by calcium monotherapy.

The mechanical properties of fluoride-treated bone in the ovariectomized rat.

The effect of fluoride therapy on the osteopenic bone of the ovariectomized rat was studied by comparing the densitometric and biomechanical data. Forty retired breeder female Sprague-Dawley rats aged 10 months were randomly divided into five groups. One group (Group A) was killed at the beginning of the study and was used as a baseline. Three groups were ovariectomized and one was sham-operated (Group B) and observed for the same period as a sham-aged group. A group of ovariectomized rats was used as a sham therapy control (Group C) and received only deionized drinking water; the other two groups (F1 and F2) received L-glutamine monofluorophosphate and calcium at a rate of 1:30 F/Ca at different doses by gavage (0.57 mg F/17 mg Ca per kg/day-Group F1; 0.21 mg F/6.30 mg Ca per kg/day-Group F2). Densitometric and biomechanical (compression and three-point bending test) assays, X-ray diffraction, and Fourier transformed infrared spectroscopy were performed on femoral specimens. Biomechanical data showed that the femoral heads of Group F2 required a significantly greater energy-to-failure than Group C (P < 0.05) as well as treated femoral diaphysis when compared with the others (P < 0.01). Significant increases in the elastic modules were observed in fluoride-treated groups (P < 0.001) when compared with other groups. Diffractometric and spectroscopic data showed the presence of fluorine-apatite in both treated groups with a high component of carbonates. Also, fluoride therapy causes an increase of bone stiffness due to the presence of fluoroapatite. It seems to produce two opposed properties in the osteopenic rat bone: a higher resistance to compression loading and a greater frailty to flexion loading.

Geometry of proximal femur in the prediction of hip fracture in osteoporotic women.

111 White post-menopausal women with hip fracture and 329 healthy controls were studied in order to determine whether proximal femur geometry predicts hip fracture and improves the discriminant ability of femoral neck bone mineral density (BMD) in elderly women. All subjects underwent dual X-ray photon absorptiometry (DXA) of the hip from which the femoral neck BMD, hip axis length, femoral neck width and femoral neck-shaft angle were measured. Fractured subjects had a lower femoral neck BMD, a longer hip axis length and a more valgus neck-shaft angle. The hip axis length correlated significantly with neck-shaft angle, femoral neck width and age. No significant correlation was found between neck-shaft angle and age. On standardized logistic regression, the hip axis length and the neck-shaft angle predicted fracture independently of BMD after correction for age, weight and femoral neck BMD. The femoral neck BMD significantly discriminated fractured subjects after correction for all potential confounders. The logistic models containing simultaneously one femoral geometric parameter and the neck BMD discriminated significantly better than those containing the same variables as single predictor. Our data suggest that hip axis length may play a role in fracture risk and supports a similar role for neck-shaft angle. Combining proximal femur geometric measurements and femoral neck BMD improved the discriminant ability of each measurement.

Simultaneous densitometry and quantitative bone sonography in the estimation of osteoporotic fracture risk.

759 post-menopausal women (41-80 years old), 175 with and 584 without vertebral fracture, were studied by quantitative bone sonography and densitometry of the distal radius in order to evaluate the ability of ultrasound transmission velocity (UTV) to separate fractured from healthy women independently of bone mineral density (BMD) and to test the possibility of improving the discriminant ability of BMD by the simultaneous use of UTV. A second BMD measurement was made at the mid radial shaft. Both BMD and UTV were higher in healthy subjects than in fractured women; the latter being older, shorter and having a longer postmenopausal status. On logistic regression, standardized for 1 SD from the mean value of healthy women, UTV differentiated between healthy and fractured subjects after correction for BMD. UTV was also a significant predictor of fracture in a selected subgroup of healthy and fractured women paired for BMD (144 pairs). In this same subgroup, the difference in UTV between fractured and healthy women regression lines was related to elasticity (E) variation between pairs. Simultaneously evaluating BMD and UTV as fracture predictors, logistic regression showed an odds ratio that was twice that of each predictor alone and 1.2 times higher than that derived from the simultaneous evaluation of two different BMD predictors. These data confirmed that UTV differentiates between healthy and fractured women both as well as and independent of BMD. In addition, UTV separated fractured from healthy BMD matched women by measuring non mass related differences. The simultaneous use of BMD and UTV improved the discriminant ability of each of them alone and of two simultaneous measurements of BMD detected at different skeletal sites.

Loss of bone mass after total hip replacement: preliminary data.

In a total of 37 females with cemented total hip replacement for monolateral coxarthrosis, of which 13 with prosthetic stem loosening, and 11 with monolateral coxarthrosis that is not prosthetized, bone mineral density (BMD) is determined by dual ray photonic absorbimetry selecting regions of interest (ROI) on the cortex of the femurs 4 cm under the lesser trochanter and on the ischium bilaterally. In females that are not prosthetized there are differences in bone mass between the two femurs and the ischium on both sides. In prosthetized patients BMD of the femur and of the ischium on the side operated on is significantly less than on the contralateral one (Student's "t" test: p < 0.001). In patients with stable prostheses, BMD of the femur operated on is greater than that in females with prosthetic stem loosening (Student's "t" test: p < 0.000). Based on a comparison between these two groups we did not observe any other significant differences in BMD among the ROI analyzed. BMD was correlated with the amount of time since surgery only in the ROIs in prosthetized femurs. The study confirms the significant bone resorption of the cortex in prosthetized femurs and documents analogously significant reduction in BMD in the ischium on the side operated on. Finally, it indicates that prosthetic stem loosening may be associated with loss of BMD in the femoral cortex which is significantly greater than that observed, during analogous periods of time in stable implants.