Risk factors for cervical and trochanteric hip fractures in elderly women: a population-based 10-year follow-up study

We evaluated the contribution of lifestyle-related factors, calcaneal ultrasound, and radial bone mineral density (BMD) to cervical and trochanteric hip fractures in elderly women in a 10-year population-based cohort study. The study population consisted of 1,681 women (age range 70-73 years). Seventy-two percent (n = 1,222) of them participated in the baseline measurements. Calcaneal ultrasound was assessed with a quantitative ultrasound device. BMD measurements were performed at the distal and ultradistal radius by dual-energy X-ray absorptiometry. Forward stepwise logistic regression analysis was used to find the most predictive variables for hip fracture risk. During the follow-up, 53 of the women had hip fractures, including 32 cervical and 21 trochanteric ones. The fractured women were taller and thinner and had lower calcaneal ultrasound values than those without fractures. High body mass index (BMI) was a protective factor against any hip fractures, while low functional mobility was a risk factor of hip fractures. Specifically, high BMI protected against cervical hip fractures, while low physical activity was a significant predictor of these fractures. Similarly, high BMI protected against trochanteric fractures, whereas low functional mobility and high coffee consumption were significant predictors of trochanteric fractures. Cervical and trochanteric hip fractures seem to have different risk factors. Therefore, fracture type should be taken into account in clinical fracture risk assessment and preventative efforts, including patient counseling. However, the study is not conclusive due to the limited number of observed fractures during follow-up, and the results have to be confirmed in future studies.

Dual-energy digital radiography for the assessment of bone mineral density

BACKGROUND

Bone mineral density (BMD) is usually determined by dual-energy X-ray absorptiometry (DXA). Digital radiography (DR) has enabled the application of dual-energy techniques for separating bone and soft tissue, but it is not clear yet whether BMD information can reliably be obtained using DR.

PURPOSE

To determine the ability of dual-energy digital radiography (DEDR) to predict BMD as determined by DXA.

MATERIAL AND METHODS

Reindeer femora (n=15) were imaged in a water bath at a typical clinical imaging voltage of 79 kVp and additionally at 100 kVp on a DR system. BMD was determined in four segmented regions (femoral neck, trochanter, inter-trochanter, Ward's triangle) from these images using the DXA calculation principle. BMD results as determined by DEDR were compared with BMD values as determined by DXA.

RESULTS

Significant moderate to high linear correlations (0.66-0.76) were observed at the femoral neck, Ward's triangle, and trochanter between BMD values as determined by the two techniques. The coefficient of variation (CV(RMS)) ranged between 2.2 and 4.7% and 0.2 and 1.8% for DEDR and DXA analyses, respectively.

CONCLUSION

DXA-based BMD information can be obtained with moderate precision and accuracy using DEDR. In future, combining BMD measurements using DEDR with structural and geometrical information available on digital radiographs could enable a more comprehensive assessment of bone.

Reindeer bone extract can heal the critical-size rat femur defect

Bone extract from reindeer induces new ectopic bone formation (BF) in muscle pouches, but its feasibility in experimental bone lesions has not been evaluated. We investigated the effects of implants, containing 2, 5, 15, 20 or 50 mg of reindeer bone extract in a collagen carrier, on the healing of 8-mm femur defects in 78 rats. We used 30 µg of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a collagen carrier, collagen and untreated defects as controls. Bone healing was evaluated with radiographs, peripheral quantitative computed tomography (pQCT), biomechanics and histology. In comparison with empty defects, the groups receiving bone extracts showed more BF at three weeks and had better bone union (BU), larger mean cross-sectional bone area at the defect site in groups receiving higher doses of extract, showed greater torsional stiffness of the bones and higher maximum breaking load of bones at six weeks. In comparison to all other groups, in the rhBMP-2 group, BF and BU were best at the three- and six-week follow-up, bone area was largest and mechanical test results were best. Although rhBMP-2 is superior for new bone regeneration, native reindeer bone extract is also effective in the six-week follow-up period.

Bioglass as a carrier for reindeer bone protein extract in the healing of rat femur defect

Bioactive glasses have been developed as scaffolds for bone tissue engineering but combination with reindeer bone protein extract has not been evaluated. We investigated the effects of bone protein extract implants (5-40 mg dosages) with bioglass (BG) carrier on the healing of rat femur defects. Bioglass implants and untreated defects served as controls. All doses of extract increased bone formation compared with the control groups, and bone union was enhanced with doses of 10 mg or more. In comparison with untreated defect, mean cross-sectional bone area at the defect site was greater when implants with BG + 15 mg of extract or bioglass alone were used, bone density at the defect site was higher in all bioglass groups with and without bone extract, and the BG + 15 mg extract dosage marginally increased bone torsional stiffness in mechanical testing. Bioglass performed well as a carrier candidate for reindeer bone protein extract.

Neuromuscular performance and body mass as indices of bone loading in premenopausal and postmenopausal women

The strong association between body mass and skeletal robusticity has been attributed to increasing skeletal loading with increasing mass. However, it is unclear whether body mass is merely a coarse substitute for bone loading rather than a true independent predictor of bone strength. As indices of neuromuscular performance, impulse and peak power were determined from vertical ground reaction force during a maximal counter movement jump test in 221 premenopausal and 82 postmenopausal women. Bone compressive (BSI(d) g(2)/cm(4)) and bending (SSImax(mid) mm(3)) strength indices were measured with peripheral quantitative computed tomography (pQCT) at the distal ((d)) and midshaft ((mid)) sites of the tibia. A two-step forced regression model for predicting bone strength indices was constructed. Age, height and body mass were entered first, followed by impulse as an indicator of skeletal loading. The basic model explained 14% (P<0.001) of the variance in BSI(d) in the premenopausal group and 16% (P=0.004) in the postmenopausal group, and 32% (P<0.001) and 25% (P<0.001) of the variance in SSImax(nud) respectively. Entering impulse into the model increased the explanatory power by 9% (P<0.001) and 7% (P<0.001) for BSI(d) and by 8% (P<0.001) and 12% (P<0.001) for SSImax(mid). Furthermore, impulse replaced body mass as an independent significant factor explaining the variance in bone strength. These results indicate that neuromuscular performance should be measured and preferred over body mass in models predicting skeletal robusticity.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on bone material properties

Dioxins are known to decrease bone strength, architecture and density. However, their detailed effects on bone material properties are unknown. Here we used nanoindentation methods to characterize the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on nanomechanical behaviour of bone matrix. Pregnant rats were treated with a single intragastric dose of TCDD (1 microg/kg) or vehicle on gestational day 11. Tibias of female offspring were sampled on postnatal day (PND) 35 or 70, scanned at mid-diaphysis with pQCT, and evaluated by three-point bending and nanoindentation. TCDD treatment decreased bone mineralization (p<0.05), tibial length (p<0.01), cross-sectional geometry (p<0.05) and bending strength (p<0.05). Controls showed normal maturation pattern between PND 35 and 70 with decreased plasticity by 5.3% and increased dynamic hardness, storage and complex moduli by 26%, 13% and 12% respectively (p<0.05), while similar maturation was not observed in TCDD-exposed pups. In conclusion, for the first time, we demonstrate retardation of bone matrix maturation process in TCDD-exposed animals. In addition, the study confirms that developmental TCDD exposure has adverse effects on bone size, strength and mineralization. The current results in conjunction with macromechanical behaviour suggest that reduced bone strength caused by TCDD is more associated with the mineralization and altered geometry of bones than with changes at the bone matrix level.

Time-course of exercise and its association with 12-month bone changes

Background

Exercise has been shown to have positive effects on bone density and strength. However, knowledge of the time-course of exercise and bone changes is scarce due to lack of methods to quantify and qualify daily physical activity in long-term. The aim was to evaluate the association between exercise intensity at 3, 6 and 12 month intervals and 12-month changes in upper femur areal bone mineral density (aBMD) and mid-femur geometry in healthy premenopausal women.

Methods

Physical activity was continuously assessed with a waist-worn accelerometer in 35 healthy women (35-40 years) participating in progressive high-impact training. To describe exercise intensity, individual average daily numbers of impacts were calculated at five acceleration levels (range 0.3-9.2 g) during time intervals of 0-3, 0-6, and 0-12 months. Proximal femur aBMD was measured with dual x-ray absorptiometry and mid-femur geometry was evaluated with quantitative computed tomography at the baseline and after 12 months. Physical activity data were correlated with yearly changes in bone density and geometry, and adjusted for confounding factors and impacts at later months of the trial using multivariate analysis.

Results

Femoral neck aBMD changes were significantly correlated with 6 and 12 months' impact activity at high intensity levels (> 3.9 g, r being up to 0.42). Trochanteric aBMD changes were associated even with first three months of exercise exceeding 1.1 g (r = 0.39-0.59, p < 0.05). Similarly, mid-femoral cortical bone geometry changes were related to even first three months' activity (r = 0.38-0.52, p < 0.05). In multivariate analysis, 0-3 months' activity did not correlate with bone change at any site after adjusting for impacts at later months. Instead, 0-6 months' impacts were significant correlates of 12-month changes in femoral neck and trochanter aBMD, mid-femur bone circumference and cortical bone attenuation even after adjustment. No significant correlations were found at the proximal or distal tibia.

Conclusion

The number of high acceleration impacts during 6 months of training was positively associated with 12-month bone changes at the femoral neck, trochanter and mid-femur. These results can be utilized when designing feasible training programs to prevent bone loss in premenopausal women.

Trial registration

Clinical trials.gov NCT00697957

Effect of impact exercise on bone metabolism

SUMMARY

Regular impact exercise in premenopausal women caused positive osteogenic effects associated to low basal serum parathormone (PTH) but had no effects on bone turnover markers PINP or TRACP5b. The low serum basal PTH levels during impact exercise may be a sign of increased incorporation of calcium to bone.

INTRODUCTION

This study aimed to determine the long-term effects of high-impact exercise on bone turnover and calciotropic hormones.

METHODS

We performed a 12-month population-based, randomized, controlled exercise trial in 120 women (age 35-40 years) randomly assigned to an exercise group (EG; n = 60) or a control group (CG; n = 60). The exercise regimen consisted of supervised high-impact exercises three times per week. Daily impact loading was assessed by using an accelerometer. Bone turnover markers and calciotropic hormones were analyzed at 0, 6, and 12 months.

RESULTS

Twelve months of impact exercise did not reveal any treatment effects in bone turnover markers PINP or TRAPC5b, whereas serum basal PTH decreased significantly more in the EG than in the CG (-11.2 vs. -2.2 pg/mL; p = 0.03). The change in PTH was dose dependent and most clearly seen in subjects with 96 to 130 daily impacts at 2.5 to 5.3 g (e.g., running or jumping).

CONCLUSIONS

Regular impact exercise does not cause persistent alterations in bone turnover emphasizing necessity of continuous training to achieve bone benefits. Impact exercise training lowers the serum basal PTH levels and possibly enables greater difference between the basal PTH and transient exercise-induced PTH peaks leading to osteogenic effects.

Correlation of tibial low-frequency ultrasound velocity with femoral radiographic measurements and BMD in elderly women

The ultrasonic axial transmission technique has been proposed as a method for cortical bone characterization. Using a low enough center frequency, Lamb modes can be excited in long bones. Lamb waves propagate throughout the cortical bone layer, which makes them appealing for characterizing bone material and geometrical properties. In the present study, a prototype low-frequency quantitative ultrasonic axial transmission device was used on elderly women (n = 132) to investigate the relationships between upper femur geometry and bone mineral density (BMD) and tibial speed of sound. Ultrasonic velocities (V) were recorded using a two-directional measurement set-up on the midtibia and compared with dual-energy X-ray absorptiometry measurements and plain radiographs of the hip. Statistically significant, but weak, correlations were found between V and femoral shaft cortex thickness measured from radiographs (r = 0.20-0.26). V also correlated significantly with various BMD and bone mineral content parameters (r = 0.20-0.35). Femoral BMD and geometry were found to be significant independent predictors of V (R(2) = 0.07-0.16, p < 0.01). This study showed that femoral geometry and BMD affect significantly the axial ultrasound velocity measured at the tibia. In addition, the results confirmed, for the first time, a relationship between tibial ultrasound velocity and cortical bone thickness at the proximal femur.

Sensitivity and specificity of fall detection in people aged 40 years and over

About one third of home-dwelling people over 65 years of age fall each year. Falling, and the fear of falling, is one of the major health risks that affects the quality of life among older people, threatening their independent living. In our pilot study, we found that fall detection with a waist-worn triaxial accelerometer is reliable with quite simple detection algorithms. The aim of this study was to validate the data collection of a new fall detector prototype and to define the sensitivity and specificity of different fall detection algorithms with simulated falls from 20 middle-aged (40-65 years old) test subjects. Activities of daily living (ADL) performed by the middle-aged subjects, and also by 21 older people (aged 58-98 years) from a residential care unit, were used as a reference. The results showed that the hardware platform and algorithms used can discriminate various types of falls from ADL with a sensitivity of 97.5% and a specificity of 100%. This suggests that the present concept provides an effective method for automatic fall detection.

High insulin levels are positively associated with peripheral nervous system function

OBJECTIVE

The aim of this study was to analyze peripheral nervous system (PNS) function in overweight and obese individuals.

MATERIALS AND METHODS

Forty-four adult non-diabetic overweight individuals were recruited. Peroneal motor nerve conduction and radial, sural, and medial plantar sensory nerve conduction were studied. Insulin and glucose levels were determined twice (over a 2- to 3-year period) with an oral glucose tolerance test (OGTT). Multiple stepwise linear regression models adjusted for age, height, weight, and skin temperature were used to analyze the data.

RESULTS

Analysis revealed that baseline insulin levels measured 120 min after an OGTT explained 18% of the variation in peroneal F-wave minimum latency, 8% of peroneal F-wave maximum latency variation, 15% of sural sensory latency variation, 13% of sural sensory nerve conduction velocity (NCV) variation, and 10% of the variation in medial plantar sensory NCV.

DISCUSSION AND CONCLUSION

Our study shows that serum insulin levels measured 120 min after an OGGT are positively associated with PNS function. High insulin levels without notably high glucose levels appear to be beneficial for the function of the PNS.

Comparison of low-complexity fall detection algorithms for body attached accelerometers

The elderly population is growing rapidly. Fall related injuries are a central problem for this population. Elderly people desire to live at home, and thus, new technologies, such as automated fall detectors, are needed to support their independence and security. The aim of this study was to evaluate different low-complexity fall detection algorithms, using triaxial accelerometers attached at the waist, wrist, and head. The fall data were obtained from standardized types of intentional falls (forward, backward, and lateral) in three middle-aged subjects. Data from activities of daily living were used as reference. Three different detection algorithms with increasing complexity were investigated using two or more of the following phases of a fall event: beginning of the fall, falling velocity, fall impact, and posture after the fall. The results indicated that fall detection using a triaxial accelerometer worn at the waist or head is efficient, even with quite simple threshold-based algorithms, with a sensitivity of 97-98% and specificity of 100%. The most sensitive acceleration parameters in these algorithms appeared to be the resultant signal with no high-pass filtering, and the calculated vertical acceleration. In this study, the wrist did not appear to be an applicable site for fall detection. Since a head worn device includes limitations concerning usability and acceptance, a waist worn accelerometer, using an algorithm that recognizes the impact and the posture after the fall, might be optimal for fall detection.

Are Signs of Temporomandibular Disorders Stable and Predictable in Adolescents With Headache?

The aim of the present study was to study changes in signs and symptoms of temporomandibular disorders (TMD) and factors predicting TMD signs in adolescents with and without headache. A population-based sample ( n = 212) of 13-year-olds with and without headache was re-examined at the age of 16. The study included a questionnaire, face-to-face interview and somatic examination. In addition, a neurological examination, a muscle evaluation and a stomatognathic examination were performed. Significant changes were seen in TMD signs during the follow-up, but TMD signs at the end of the follow-up could not be predicted by baseline headache, sleeping difficulties, depression or muscle pain. TMD signs at the age of 16 were associated with female gender and muscle pain. We conclude that considerable changes in TMD signs occur in the follow-up of adolescents with and without headache. Headache-related TMD are not predictable in adolescents with and without headache.

Experimental hip fracture load can be predicted from plain radiography by combined analysis of trabecular bone structure and bone geometry

Computerized analysis of the trabecular structure was used to test whether femur failure load can be estimated from radiographs. The study showed that combined analysis of trabecular bone structure and geometry predicts in vitro failure load with similar accuracy as DXA.

INTRODUCTION

Since conventional radiography is widely available with low imaging cost, it is of considerable interest to discover how well bone mechanical competence can be determined using this technology. We tested the hypothesis that the mechanical strength of the femur can be estimated by the combined analysis of the bone trabecular structure and geometry.

METHODS

The sample consisted of 62 cadaver femurs (34 females, 28 males). After radiography and DXA, femora were mechanically tested in side impact configuration. Fracture patterns were classified as being cervical or trochanteric. Computerized image analysis was applied to obtain structure-related trabecular parameters (trabecular bone area, Euler number, homogeneity index, and trabecular main orientation), and set of geometrical variables (neck-shaft angle, medial calcar and femoral shaft cortex thicknesses, and femoral neck axis length). Multiple linear regression analysis was performed to identify the variables that best explain variation in BMD and failure load between subjects.

RESULTS

In cervical fracture cases, trabecular bone area and femoral neck axis length explained 64% of the variability in failure loads, while femoral neck BMD also explained 64%. In trochanteric fracture cases, Euler number and femoral cortex thickness explained 66% of the variability in failure load, while trochanteric BMD explained 72%.

CONCLUSIONS

Structural parameters of trabecular bone and bone geometry predict in vitro failure loads of the proximal femur with similar accuracy as DXA, when using appropriate image analysis technology.

Determination of simple thresholds for accelerometry-based parameters for fall detection

The increasing population of elderly people is mainly living in a home-dwelling environment and needs applications to support their independency and safety. Falls are one of the major health risks that affect the quality of life among older adults. Body attached accelerometers have been used to detect falls. The placement of the accelerometric sensor as well as the fall detection algorithms are still under investigation. The aim of the present pilot study was to determine acceleration thresholds for fall detection, using triaxial accelerometric measurements at the waist, wrist, and head. Intentional falls (forward, backward, and lateral) and activities of daily living (ADL) were performed by two voluntary subjects. The results showed that measurements from the waist and head have potential to distinguish between falls and ADL. Especially, when the simple threshold-based detection was combined with posture detection after the fall, the sensitivity and specificity of fall detection were up to 100 %. On the contrary, the wrist did not appear to be an optimal site for fall detection.

Biocompatilibity-related surface characteristics of oxidized NiTi

In the present study, we examined the effect of NiTi oxidation on material surface characteristics related to biocompatibility. Correspondence between electron work function (EWF) and adhesive force predicted by electron theory of adsorption as well as the effect of surface mechanical stress on the adhesive force were studied on the nonoxidized and oxidized at 350, 450, and 600 degrees C NiTi alloy for medical application. The adhesive force generated by the material surface towards the drops of alpha-minimal essential medium (alpha-MEM) was used as a characteristic of NiTi adsorption properties. The study showed that variations in EWF and mechanical stress caused by surface treatment were accompanied by variations in adhesive force. NiTi oxidation at all temperatures used gave rise to decrease in adhesive force and surface stress values in comparison to the nonoxidized state. In contrary, the EWF value revealed increase under the same condition. Variations in surface oxide layer thickness and its phase composition were also followed. The important role of oxide crystallite size in EWF values within the range of crystallite dimensions typical for NiTi surface oxide as an instrument for the fine regulation of NiTi adsorption properties was demonstrated. The comparative oxidation of pure titanium and NiTi showed that the effect of Ni on the EWF value of NiTi surface oxide is negligible.