Investigating the predictive ability of gait speed and quadriceps strength for incident falls in community-dwelling older women at high risk of fracture

Gait speed is a recommended geriatric assessment of physical performance, but may not be regularly examined in clinical settings. We aimed to investigate whether quadriceps strength tests demonstrate similar predictive ability for incident falls as gait speed in older women. We investigated 135 female volunteers aged mean±SD 76.7±5.0 years (range 70-92) at high risk of fracture. Participants completed gait speed assessments using the GAITRite Electronic Walkway System, and quadriceps strength assessments using a hand-held dynamometer (HHD). Participants reported incident falls monthly for 3.7±1.2 years. N=99 (73%) participants fell 355 times during the follow-up period (mean fall rate 83 per 100 person years). We observed a reduced odds ratio for multiple falls (0.83, 95% CI 0.70-0.98) and a reduced hazard ratio for time to first fall (0.90, 95% CI 0.83-0.98), according to quadriceps strength. There was also a significantly shorter time to first fall for those with low quadriceps strength (<7.0 kg; lowest tertile) compared with those with normal quadriceps strength (estimated means [95% CI] 1.54 [1.02, 2.06] vs. 2.23 [1.82, 2.64] years; P=0.019), but not for those with low (<1.0 m/s) vs. normal gait speed (P=0.15). Quadriceps strength is a significant predictor of incident falls over three years amongst community-dwelling older women at high risk of fracture. Quadriceps strength tests may be an acceptable alternative to gait speed for geriatric assessments of falls risk.

Modeling of shear ductile fracture considering a changeable cut-off value for stress triaxiality

 A macroscopic ductile fracture criterion is proposed based on micro-mechanism analysis of nucleation, growth and shear coalescence of voids from experimental observation of fracture surfaces. The proposed ductile fracture model endows a changeable cut-off value for the stress triaxiality to represent effect of micro-structures, the Lode parameter, temperature, and strain rate on ductility of metals. The proposed model is used to construct fracture loci of AA 2024- T351. The constructed fracture loci are compared with experimental data covering wide stress triaxiality ranging between –0.5 and 1.0. The comparison suggests that the proposed model can provide a satisfactory prediction of ductile fracture for metals from compressive upsetting tests to plane strain tension with slanted fracture surfaces. Moreover, it is expected that the proposed model reasonably describes ductile fracture behavior in high velocity perforation simulation since a reasonable cut-off value for the stress triaxiality is coupled with the proposed ductile fracture criterion.

Modified Mohr-Coulomb fracture model for anisotropic sheet materials under limited triaxial stress conditions

 This paper reviews recent work of the authors to model necking and fracture for anisotropic materials, which requires consideration of the stress conditions that vary through the thickness of the sheet, and in particular, taking into consideration the conditions at individual integration points. Although the prior work adequately addresses the roll of triaxial stress conditions on necking, the fracture model developed in the prior work was limited in its application to analysis of plane-stress conditions. In this work, a fracture model is developed for application to a limited range of triaxial stress conditions, in which the through-thickness shear stresses are assumed to be negligible, but the normal stress is allowed to be non-zero. The model is extended in a way that reduces to the prior anisotropic fracture model under plane stress conditions, but includes the contribution of a triaxial stress condition in a way that retains the desired features
of the Mohr-Coulomb Model.

Age- and sex-related patterns of first fracture and fracture prevalence

There are few data documenting the pattern of prevalent fracture across the entire adult age range, so we aimed to address this gap by investigating the prevalence of fractures in an Australian cohort. All-cause (ever) fractures were identified for males and females enrolled in the Geelong Osteoporosis Study (Australia) using a combination of radiology-confirmed and self-reported data. First fractures were used to generate age-related frequencies of individuals who had ever sustained a fracture. Of 1,538 males and 1,731 females, 927 males and 856 females had sustained at least one fracture since birth. The proportion of all prevalent fractures in the 0-10 year age group was similar for both sexes (~10 %). In males, the proportion with prevalent fracture increased to 34.1 % for age 11-20 year. Smaller increases were observed into mid-life, reaching a plateau at ~50 % from mid to late life. The age-related prevalence of fracture for females showed a more gradual increase until mid-life. For adulthood prevalent fractures, approximately 20 % of males had sustained a first adulthood fracture in the 20-30 year age group, with a gradual increase up to the oldest age group (49.1 %), while females showed an exponential pattern of increase from the 20-30 year age group (6.8 %) to the oldest age group (60.4 %). In both sexes, those who had not sustained a fracture in childhood or early adulthood generally appeared to remain fracture-free until at least the sixth decade. When considering the prevalence of adulthood fractures across the age groups, males showed a gradual increase while females showed an exponential increase.

Adulthood fracture and quality of life : A population-based study of Australian men

Background: Our objective was to investigate associations between adulthood fracture and quality of life (QOL) in men. Methods: For 448 men aged 50-85 years and enrolled in the Geelong Osteoporosis Study, we measured QOL using the validated (Australian) World Health Organization Quality of Life-Brief Version (WHOQOL-Bref) in the domains of physical health, psychological health, social relationships, and the environment. Self-reported adulthood fractures were categorized as recent or non-recent ( ≤ 10 years or > 10 years pre-QOL assessment, respectively). Lifestyle and health information were self-reported. Results: One hundred seventy four men (38.8%) sustained at least one fracture, 26% of which had occurred within the last 10 years. Compared with men who had never had an adulthood fracture, a non-recent fracture was more likely associated with poorer QOL in the physical health domain (age-adjusted odds ratio [OR] 0.47, 95% confidence interval [95%CI] 0.27-0.83), but not in any other domain. Men who had sustained a recent fracture reported a lower QOL in the domain of psychological health (age-adjusted OR 0.48, 95%CI 0.24-0.97), with a trend observed for lower QOL in the domains of physical health and environment. No further associations were observed. All results were sustained in further models that were adjusted for smoking, alcohol, physical inactivity, and body mass index. Conclusions: We present novel data examining associations between fracture status and QOL in a populationbased sample of Australian men using the WHOQOL-Bref. Recent fractures were associated with poorer QOL in the domain of psychological health while non-recent fractures were more likely associated poorer QOL for physical health. These findings have important implications for healthcare post-fracture.

Numerical investigation of influence of the Martensite Volume Fraction on dp steels fracture behavior on the basis of digital material representation model

Development of the methodology for creating reliable digital material representation (DMR) models of dual-phase steels and investigation of influence of the martensite volume fraction on fracture behavior under tensile load are the main goals of the paper. First, an approach based on image processing algorithms for creating a DMR is described. Then, obtained digital microstructures are used as input for the numerical model of deformation, which takes into account mechanisms of ductile fracture. Ferrite and martensite material model parameters are evaluated on the basis of micropillar compression tests. Finally, the model is used to investigate the impact of the martensite volume fraction on the DP steel behavior under plastic deformation. Results of calculations are presented and discussed in the paper.

Is there an interaction between socioeconomic status and FRAX 10-year fracture probability determined with and without bone density measures? Data from the Geelong Osteoporosis Study of female cohort.

FRAX(©) evaluates 10-year fracture probabilities and can be calculated with and without bone mineral density (BMD). Low socioeconomic status (SES) may affect BMD, and is associated with increased fracture risk. Clinical risk factors differ by SES; however, it is unknown whether aninteraction exists between SES and FRAX determined with and without the BMD. From the Geelong Osteoporosis Study, we drew 819 females aged ≥50 years. Clinical data were collected during 1993-1997. SES was determined by cross-referencing residential addresses with Australian Bureau of Statistics census data and categorized in quintiles. BMD was measured by dual energy X-ray absorptiometry at the same time as other clinical data were collected. Ten-year fracture probabilities were calculated using FRAX (Australia). Using multivariable regression analyses, we examined whether interactions existed between SES and 10-year probability for hip and any major osteoporotic fracture (MOF) defined by use of FRAX with and without BMD. We observed a trend for a SES * FRAX(no-BMD) interaction term for 10-year hip fracture probability (p = 0.09); however, not for MOF (p = 0.42). In women without prior fracture (n = 518), we observed a significant SES * FRAX(no-BMD) interaction term for hip fracture (p = 0.03) and MOF (p = 0.04). SES does not appear to have an interaction with 10-year fracture probabilities determined by FRAX with and without BMD in women with previous fracture; however, it does appear to exist for those without previous fracture.

The social gradient of fractures at any skeletal site in men and women: data from the Geelong Osteoporosis Study Fracture Grid.

Age-specific and age-standardized associations between socioeconomic status (SES) and fractures in adults showed a social gradient of fracture, irrespective of fracture site. Compared to the highest SES, males in the lowest SES group had a sixfold increased odds for any fracture, whilst females had a twofold increased odds.

Investigation of hydraulic fracture propagation using a post-peak control system coupled with acoustic emission

This study investigates the fracture mechanism of fluid coupled with a solid resulting from hydraulic fracture. A new loading machine was designed to improve upon conventional laboratory hydraulic fracture testing and to provide a means of better understanding fracture behavior of solid media. Test specimens were made of cement mortar. An extensometer and acoustic emission (AE) monitoring system recorded the circumferential deformation and crack growth location/number during the test. To control the crack growth at the post-peak stage the input fluid rate can be adjusted automatically according to feedback from the extensometer. The complete stress-deformation curve, including pre- and post-peak stages, was therefore obtained. The crack extension/growth developed intensively after the applied stress reached the breakdown pressure. The number of cracks recorded by the AE monitoring system was in good agreement with the amount of deformation (expansion) recorded by the extensometer. The results obtained in this paper provide a better understanding of the hydraulic fracture mechanism which is useful for underground injection projects. © 2014 Springer-Verlag Wien.

Carpal and scaphoid fracture incidence in south-eastern Australia: an epidemiologic study

UNLABELLED: Carpal fractures were identified by the Geelong Osteoporosis Study Fracture Grid for 2006-2007. Incidence rates were higher in males than females. Males had a lower median age of fracture than females. Females had more fractures on the left side than males. Most fractures were the result of a fall. PURPOSE: In this study, we report the incidence of carpal bone fractures (scaphoid and non-scaphoid) amongst residents from the Barwon Statistical Division over 2 years. METHODS: X-ray reports from imaging centres in the region were used to identify incident fractures during 2006 and 2007. Data were collected as part of the Geelong Osteoporosis Study Fracture Grid. RESULTS: During 2006 and 2007, there were 171 and 41 carpal fractures in males and females, respectively. Of these, 131 males and 29 females had fractured the scaphoid bone. Females had a higher proportion of left-sided fractures (>70 %) than males (∼40 %). Most fractures were the result of an accidental fall (>87 %). Patterns of incidence for males showed one major peak around 20-29 years. For females, peaks occurred around age 10-19 years and 70-79 years. Incidence rates for males (per 100,000 persons per year) were 54.6 (95 % confidence interval (CI) 53.6, 55.7) and 15.9 (95 % CI 15.4, 16.5) for scaphoid and non-scaphoid fractures, respectively. In females, the corresponding rates were 10.6 (95 % CI 10.2, 11.1) and 4.5 (95 % CI 4.2, 4.8). CONCLUSION: Almost all fractures were the result of a fall. In males, carpal fractures were sustained mainly during early adulthood and in females during adolescence and after menopause. Incidence rates for males were higher than those in females for both scaphoid and non-scaphoid fractures.

A randomised controlled trial of low-dose aspirin for the prevention of fractures in healthy older people : protocol for the ASPREE-Fracture substudy

Background Disability, mortality and healthcare burden from fractures in older people is a growing problem worldwide. Observational studies suggest that aspirin may reduce fracture risk. While these studies provide room for optimism, randomised controlled trials are needed. This paper describes the rationale and design of the ASPirin in Reducing Events in the Elderly (ASPREE)-Fracture substudy, which aims to determine whether daily low-dose aspirin decreases fracture risk in healthy older people. Methods ASPREE is a double-blind, randomised, placebo-controlled primary prevention trial designed to assess whether daily active treatment using low-dose aspirin extends the duration of disability-free and dementia-free life in 19 000 healthy older people recruited from Australian and US community settings. This substudy extends the ASPREE trial data collection to determine the effect of daily low-dose aspirin on fracture and fall-related hospital presentation risk in the 16 500 ASPREE participants aged ≥70 years recruited in Australia. The intervention is a once daily dose of enteric-coated aspirin (100 mg) versus a matching placebo, randomised on a 1:1 basis. The primary outcome for this substudy is the occurrence of any fracture-vertebral, hip and non-vert-non-hip-occurring post randomisation. Fall-related hospital presentations are a secondary outcome. Discussion This substudy will determine whether a widely available, simple and inexpensive health intervention-aspirin-reduces the risk of fractures in older Australians. If it is demonstrated to safely reduce the risk of fractures and serious falls, it is possible that aspirin might provide a means of fracture prevention.

Fall and fracture risk in sarcopenia and dynapenia with and without obesity: the role of lifestyle interventions

Due to their differing etiologies and consequences, it has been proposed that the term "sarcopenia" should revert to its original definition of age-related muscle mass declines, with a separate term, "dynapenia", describing muscle strength and function declines. There is increasing interest in the interactions of sarcopenia and dynapenia with obesity. Despite an apparent protective effect of obesity on fracture, increased adiposity may compromise bone health, and the presence of sarcopenia and/or dynapenia ("sarcopenic obesity" and "dynapenic obesity") may exacerbate the risk of falls and fracture in obese older adults. Weight loss interventions are likely to be beneficial for older adults with sarcopenic and dynapenic obesity but may result in further reductions in muscle and bone health. The addition of exercise including progressive resistance training and nutritional strategies, including protein and vitamin D supplementation, may optimise body composition and muscle function outcomes thereby reducing falls and fracture risk in this population.

The effect of surgical timing on the outcome of patients with neck of femur fracture

Aims: To investigate the effect of surgical timing (in hours versus after hours and weekdays versus weekends) on the outcome of patients with neck of femur fracture. Methods: Patients who were admitted to a single tertiary referral hospital for surgical management of femoral neck fractures over a continuous period from 1/11/2002 to 12/7/2012 were identified from medical records and the operating theatre database. Results: A consecutive series of 2334 patients were included in the study. Of the patients who underwent surgery during the weekday and during usual hours, 18 % (207/1135) experienced an adverse event, compared to 16 % (193/1199) outside of these times. The difference between the two groups was not significant (p = 0.17). The same conclusion was made for the comparison between those who had surgery during the week with those who had surgery on the weekend (17 %, 267/1546 and 17 %, 133/788, respectively, p > 0.05). The proportion of patients who underwent surgery during hours that experienced an adverse event was significantly higher than those undergoing surgery out of hours (18 %, 327/1789 and 13 %, 73/545, respectively, p = 0.0081). When adjusted for age, ASA score and pre-operative stay, there was no statistical difference between those different sub-groups. Conclusions: There was no difference in the rates of adverse events between patients who had surgery during hours and weekdays with those who had surgery after hours or weekends. The careful selection of patients with appropriate hospital staff, resources and adequate theatre access, surgery during after hours and weekends may be safely considered to prevent a delay in surgical treatment for patient with neck of femur fracture.

Anisotropic behavior in plasticity and ductile fracture of an aluminum alloy

Anisotropic mechanical behavior is investigated for an aluminum alloy of 6K21-IH T4 both in plastic deformation and ductile fracture. Anisotropic plastic deformation is characterized by uniaxial tensile tests of dog-bone specimens, while anisotropy in ductile fracture is illustrated with specimens with a central hole, notched specimens and shear specimens. All these specimens are cut off at every 15º from the rolling direction. The r-values and uniaxial tensile yield stresses are measured from the tensile tests of dog-bone specimens. Then the anisotropic plasticity is modeled by a newly proposed J2-J3 criterion under non-associate flow rule (non-AFR). The testing processes of specimens for ductile fracture analysis are simulated to extract the maximum plastic strain at fracture strokes as well as the evolution of the stress triaxiality and the Lode parameter in different testing directions. The measured fracture behavior is described by a shear-controlled ductile fracture criterion proposed by Lou et al. (2014. Modeling of shear ductile fracture considering a changeable cut-off value for stress triaxiality. Int. J. Plasticity 54, 56-80) for different loading directions. It is demonstrated that the anisotropic plastic deformation is described by the J2-J3 criterion with high accuracy in various loading conditions including shear, uniaxial tension and plane strain tension. Moreover, the anisotropy in ductile fracture is not negligible and cannot be modeled by isotropic ductile fracture criteria. Thus, an anisotropic model must be proposed to accurately illustrate the directionality in ductile fracture.