The effect on subsequent fracture risk of age, sex, and prior fracture site by recency of prior fracture.

The risk of a recurrent fragility fracture varies by age and sex, as by site and recency of sentinel fracture. INTRODUCTION: The recency of prior fractures affects subsequent fracture risk. Variable recency may obscure other factors that affect subsequent fracture risk. The aim of this study was to quantify the effect of a sentinel fracture by site, age, and sex where the recency was held constant. METHODS: The study used data from the Reykjavik Study fracture register that documented prospectively all fractures at all skeletal sites in a large sample of the population of Iceland. Fracture incidence was compared to that of the general population determined at fixed times after a sentinel fracture (humeral, clinical vertebral, forearm, hip, and minor fractures). Outcome fractures comprised a major osteoporotic fracture and hip fracture. RESULTS: Sentinel osteoporotic fractures were identified in 9504 men and women. Of these, 3616 individuals sustained a major osteoporotic fracture as the first subsequent fracture, of whom 1799 sustained a hip fracture. Hazard ratios for prior fracture were consistently higher in men than in women and decreased progressively with age. Hazard ratios varied according to the site of sentinel fracture with higher ratios for hip and vertebral fracture than for humerus, forearm, or minor osteoporotic fracture. CONCLUSION: The risk of a recurrent fragility fracture varies by age, sex, and site of sentinel fracture when recency is held constant.

The use of 2-, 5-, and 10-year probabilities to characterize fracture risk after a recent sentinel fracture.

The increase in fracture risk associated with a recent fragility fracture is more appropriately captured using a 10-year fracture probability than 2- or 5-year probabilities. INTRODUCTION: The recency of prior fractures affects subsequent fracture risk. The aim of this study was to quantify the effect of a recent sentinel fracture, by site, on the 2-, 5-, and 10-year probability of fracture. METHODS: The study used data from the Reykjavik Study fracture register that documented prospectively all fractures at all skeletal sites in a large sample of the population of Iceland. Fracture probabilities were determined after a sentinel fracture (humeral, clinical vertebral, forearm and hip fracture) occurring within the previous 2 years and probabilities for a prior osteoporotic fracture irrespective of recency. The probability ratios were used to adjust fracture probabilities over a 2-, 5-, and 10-year time horizon. RESULTS: As expected, probabilities decreased with decreasing time horizon. Probability ratios varied according to age and the site of sentinel fracture. Probability ratios to adjust for a prior fracture within the previous 2 years were higher the shorter the time horizon, but the absolute increases in fracture probabilities were much reduced. Thus, fracture probabilities were substantially lower with time horizons less than 10 years. CONCLUSION: The 10-year probability of fractures is the appropriate metric to capture the impact of the recency of sentinel fractures. The probability ratios provide adjustments to conventional FRAX estimates of fracture probability for recent sentinel fractures, adjustments which can readily inform clinical decision-making.

Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study.

Poor physical function and body composition my partly predict the risk of falls leading to fracture regardless of bone mineral density. INTRODUCTION: To examine the relationship between body composition, physical function, and other markers of health with hip fractures in older community-dwelling Icelandic adults. METHODS: A prospective cohort of 4782 older adults from the AGES-Reykjavik study. Baseline recruitment took place between 2002 and 2006, and information on hip fractures occurring through 2012 was extracted from clinical records. Using multivariate regression analyses, baseline measures of bone health, physical function, and body composition were compared between those who later experienced hip fractures and to those who did not. Associations with the risk of fractures were quantified using Cox regression. RESULTS: Mean age was 76.3 years at baseline. After adjustment for age, regression showed that male hip fracture cases compared with non-cases had (mean (95% confidence interval)) significantly lower thigh muscle cross-sectional area - 5.6 cm2 (- 10.2, - 1.1), poorer leg strength - 28 N (- 49, - 7), and decreased physical function as measured by longer timed up and go test 1.1 s (0.5, 1.7). After adjustment for age, female cases had, compared with non-cases, lower body mass index - 1.5 kg/m2 (- 2.1, - 0.9), less lean mass - 1.6 kg (- 2.5, - 0.8), thigh muscle cross-sectional area - 4.4 cm2 (- 6.5, - 2.3), and worse leg strength - 16 N (- 25, - 6). These differences largely persisted after further adjustment for bone mineral density (BMD), suggesting that body composition may contribute to the risk of fracture independent of bone health. When examining the association between these same factors and hip fractures using Cox regression, the same conclusions were reached. CONCLUSIONS: After accounting for age and BMD, older adults who later experienced a hip fracture had poorer baseline measures of physical function and/or body composition, which may at least partly contribute to the risk of falls leading to fracture.

Correction to: Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study.

The original version of this article, published on 18 august 2020 contained a mistake. An author's name was misspelled.

Adjusting conventional FRAX estimates of fracture probability according to the recency of sentinel fractures.

The risk of a recurrent fragility fracture is particularly high immediately following the fracture. This study provides adjustments to FRAX-based fracture probabilities accounting for the site of a recent fracture. INTRODUCTION: The recency of prior fractures affects subsequent fracture risk. The aim of this study was to quantify the effect of a recent sentinel fracture, by site, on the 10-year probability of fracture determined with FRAX. METHODS: The study used data from the Reykjavik Study fracture register that documented prospectively all fractures at all skeletal sites in a large sample of the population of Iceland. Fracture probabilities were determined after a sentinel fracture (humeral, clinical vertebral, forearm and hip fracture) from the hazards of death and fracture. Fracture probabilities were computed on the one hand for sentinel fractures occurring within the previous 2 years and on the other hand, probabilities for a prior osteoporotic fracture irrespective of recency. The probability ratios provided adjustments to conventional FRAX estimates of fracture probability for recent sentinel fractures. RESULTS: Probability ratios to adjust 10-year FRAX probabilities of a major osteoporotic fracture for recent sentinel fractures were age dependent, decreasing with age in both men and women. Probability ratios varied according to the site of sentinel fracture with higher ratios for hip and vertebral fracture than for humerus or forearm fracture. Probability ratios to adjust 10-year FRAX probabilities of a hip fracture for recent sentinel fractures were also age dependent, decreasing with age in both men and women with the exception of forearm fractures. CONCLUSION: The probability ratios provide adjustments to conventional FRAX estimates of fracture probability for recent sentinel fractures.

Characteristics of recurrent fractures.

The present study, drawn from a sample of the Icelandic population, quantified high immediate risk and utility loss of subsequent fracture after a sentinel fracture (at the hip, spine, distal forearm and humerus) that attenuated with time. INTRODUCTION: The risk of a subsequent osteoporotic fracture is particularly acute immediately after an index fracture and wanes progressively with time. The aim of this study was to quantify the risk and utility consequences of subsequent fracture after a sentinel fracture (at the hip, spine, distal forearm and humerus) with an emphasis on the time course of recurrent fracture. METHODS: The Reykjavik Study fracture registration, drawn from a sample of the Icelandic population (n = 18,872), recorded all fractures of the participants from their entry into the study until December 31, 2012. Medical records for the participants were manually examined and verified. First sentinel fractures were identified. Subsequent fractures, deaths, 10-year probability of fracture and cumulative disutility using multipliers derived from the International Costs and Utilities Related to Osteoporotic fractures Study (ICUROS) were examined as a function of time after fracture, age and sex. RESULTS: Over 10 years, subsequent fractures were sustained in 28% of 1498 individuals with a sentinel hip fracture. For other sentinel fractures, the proportion ranged from 35 to 38%. After each sentinel fracture, the risk of subsequent fracture was highest in the immediate post fracture interval and decreased markedly with time. Thus, amongst individuals who sustained a recurrent fracture, 31-45% did so within 1 year of the sentinel fracture. Hazard ratios for fracture recurrence (population relative risks) were accordingly highest immediately after the sentinel fracture (2.6-5.3, depending on the site of fracture) and fell progressively over 10 years (1.5-2.2). Population relative risks also decreased progressively with age. The utility loss during the first 10 years after a sentinel fracture varied by age (less with age) and sex (greater in women). In women at the age of 70 years, the mean utility loss due to fractures in the whole cohort was 0.081 whereas this was 12-fold greater in women with a sentinel hip fracture, and was increased 15-fold for spine fracture, 4-fold for forearm fracture and 8-fold for humeral fracture. CONCLUSION: High fracture risks and utility loss immediately after fracture suggest that treatment given as soon as possible after fracture would avoid a higher number of new fractures compared with treatment given later. This provides the rationale for very early intervention immediately after a sentinel fracture.

Imminent risk of fracture after fracture.

The risk of major osteoporotic fracture (MOF) after a first MOF is increased over the whole duration of follow-up, but the imminent risk is even higher. If the acute increment in risk in the few years following MOF is amenable to therapeutic intervention, then immediate short-term treatments may provide worthwhile clinical dividends in a very cost-effective manner. INTRODUCTION: A history of fracture is a strong risk factor for future fractures. The aim of the present study was to determine whether the predictive value of a past MOF for future MOF changed with time. METHODS: The study was based on a population-based cohort of 18,872 men and women born between 1907 and 1935. Fractures were documented over 510,265 person-years. An extension of Poisson regression was used to investigate the relationship between the first MOF and the second. All associations were adjusted for age and time since baseline. RESULTS: Five thousand thirty-nine individuals sustained one or more MOFs, of whom 1919 experienced a second MOF. The risk of a second MOF after a first increased by 4% for each year of age (95% CI 1.02-1.06) and was 41% higher for women than men (95% CI 1.25-1.59). The risk of a second MOF was highest immediately after the first fracture and thereafter decreased with time though remained higher than the population risk throughout follow-up. For example, 1 year after the first MOF, the risk of a second fracture was 2.7 (2.4-3.0) fold higher than the population risk. After 10 years, this risk ratio was 1.4 (1.2-1.6). The effect was more marked with increasing age. CONCLUSIONS: The risk of MOF after a first MOF is increased over the whole follow-up, but the imminent risk is even higher. If the acute increment in risk in the few years following MOF is amenable to therapeutic intervention, then immediate short-term treatments may provide worthwhile clinical dividends in a very cost-effective manner, particularly in the elderly.

Are bone turnover markers associated with volumetric bone density, size, and strength in older men and women? The AGES-Reykjavik study.

UNLABELLED: Association between serum bone formation and resorption markers and bone mineral, structural, and strength variables derived from quantitative computed tomography (QCT) in a population-based cohort of 1745 older adults was assessed. The association was weak for lumbar spine and femoral neck areal and volumetric bone mineral density. INTRODUCTION: The aim of this study was to examine the relationship between levels of bone turnover markers (BTMs; osteocalcin (OC), C-terminal cross-linking telopeptide of type I collagen (CTX), and procollagen type 1N propeptide (P1NP)) and quantitative computed tomography (QCT)-derived bone density, geometry, and strength indices in the lumbar spine and femoral neck (FN). METHODS: A total of 1745 older individuals (773 men and 972 women, aged 66-92 years) from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik cohort were studied. QCT was performed in the lumbar spine and hip to estimate volumetric trabecular, cortical, and integral bone mineral density (BMD), areal BMD, bone geometry, and bone strength indices. Association between BTMs and QCT variables were explored using multivariable linear regression. RESULTS: Major findings showed that all BMD measures, FN cortical index, and compressive strength had a low negative correlation with the BTM levels in both men and women. Correlations between BTMs and bone size parameters were minimal or not significant. No associations were found between BTMs and vertebral cross-sectional area in women. BTMs alone accounted for only a relatively small percentage of the bone parameter variance (1-10 %). CONCLUSION: Serum CTX, OC, and P1NP were weakly correlated with lumbar spine and FN areal and volumetric BMD and strength measures. Most of the bone size indices were not associated with BTMs; thus, the selected bone remodeling markers do not reflect periosteal bone formation. These results confirmed the limited ability of the most sensitive established BTMs to predict bone structural integrity in older adults.

Association of bone turnover markers with volumetric bone loss, periosteal apposition, and fracture risk in older men and women: the AGES-Reykjavik longitudinal study.

Association between serum bone formation and resorption markers and cortical and trabecular bone loss and the concurrent periosteal apposition in a population-based cohort of 1069 older adults was assessed. BTM levels moderately reflect the cellular events at the endosteal and periosteal surfaces but are not associated with fracture risk. INTRODUCTION: We assessed whether circulating bone formation and resorption markers (BTM) were individual predictors for trabecular and cortical bone loss, periosteal expansion, and fracture risk in older adults aged 66 to 93 years from the AGES-Reykjavik study. METHODS: The sample for the quantitative computed tomography (QCT)-derived cortical and trabecular BMD and periosteal expansion analysis consisted of 1069 participants (474 men and 595 women) who had complete baseline (2002 to 2006) and follow-up (2007 to 2011) hip QCT scans and serum baseline BTM. During the median follow-up of 11.7 years (range 5.4-12.5), 54 (11.4 %) men and 182 (30.6 %) women sustained at least one fracture of any type. RESULTS: Increase in BTM levels was associated with faster cortical and trabecular bone loss at the femoral neck and proximal femur in men and women. Higher BTM levels were positively related with periosteal expansion rate at the femoral neck in men. Markers were not associated with fracture risk. CONCLUSION: This data corroborates the notion from few previous studies that both envelopes are metabolically active and that BTM levels may moderately reflect the cellular events at the endosteal and periosteal surfaces. However, our results do not support the routine use of BTM to assess fracture risk in older men and women. In light of these findings, further studies are justified to examine whether systemic markers of bone turnover might prove useful in monitoring skeletal remodeling events and the effects of current osteoporosis drugs at the periosteum.

Epidemiology of fractures in Iceland and secular trends in major osteoporotic fractures 1989-2008.

UNLABELLED: The incidence of the most common fracture types in Iceland is reported based on individual data from the Reykjavik Study 1967-2008. Time trend is reported for the major osteoporotic fractures (MOS) 1989-2008. INTRODUCTION: This study aims to assess the incidence of all fractures in Iceland, with emphasis on the rate of hip fractures, and compare the incidence with other populations as well as examine the secular changes. METHODS: Individuals from the prospective population-based cohort Reykjavik Study were examined between 1967 and 2008 (follow-up 26.5 years), which consisted of 9,116 men and 9,756 women born in 1907-1935, with age range 31-81 years. First fracture incidence was estimated using life table methods with age as the timescale. RESULTS: Fracture rate increased proportionally with age between the sexes for vertebral and proximal humerus but disproportionally for hip and distal forearm fractures. The ratio of first fracture incidence between the sexes varied considerably by site: 2.65 for hip fractures and the highest for distal forearm fractures at 4.83. By the age of 75, 36.7% of women and 21% of men had sustained a fracture, taking into account competing risk of death. The incidence of hip fractures was similar to results previously published from USA, Sweden, Norway, and Scotland. The incidence of MOS fractures in both sexes decreased over the last decade, except hip fractures in men, which remained unchanged, as reflected in the women/men ratio for the hip, which changed from 2.6 to 1.7. CONCLUSION: This study adds information to scarce knowledge on the relative fracture incidence of different fractures. The incidence of MOS fractures increased in the latter part of the last century in both sexes and declined during the last decade, less dramatically for men. This information is important for planning health resources.

The incidence of a first major osteoporotic fracture in Iceland and implications for FRAX.

SUMMARY: Based on an extensive cohort study over 25 years, the present study supports the assumption that major osteoporotic fractures can be reasonably predicted from hip fracture rates. INTRODUCTION: The construct for FRAX models depends on algorithms to adjust for double counting of fracture outcomes in some models and in others, to estimate the incidence of a major fracture from hip fracture rates. The aim of the present study was to test the validity of these algorithms in a large prospective cohort. METHODS: The incidence of hip, clinical spine, distal forearm, and humerus fracture was determined in the prospective and ongoing population-based Reykjavik Study with follow up of 257,001 person-years. The incidence of a first major fracture was compared with the correction factors used in FRAX to adjust the incidence of several fracture outcomes for double counting. In addition, the incidence of a major osteoporotic fracture estimated from the Icelandic hip fracture rates was compared with the Malmo ratios used in FRAX. RESULTS: The adjustments necessary to account for multiple fracture outcomes were similar to those previously derived from Sweden. Additionally, incidence of a first major osteoporotic fracture was similar to that derived for FRAX models. CONCLUSION: The findings of the present study support the algorithms used in FRAX to estimate the incidence of a first major fracture and the predictive value of hip fracture for other major fractures.

Co-Presence of Multimorbidity and Disability with Frailty: An Examination of Heterogeneity in the Frail Older Population.

BACKGROUND: Frailty is often associated with multimorbidity and disability. OBJECTIVES: We investigated heterogeneity in the frail older population by characterizing five subpopulations according to quantitative biological markers, multimorbidity and disability, and examined their association with mortality and nursing home admission. DESIGN: Observational study. PARTICIPANTS: Participants (n=4,414) were from the population-based Age Gene/Environment Susceptibility Reykjavik Study. MEASUREMENTS: Frailty was defined by ≥ 3 of five characteristics: weight loss, weakness, reduced energy levels, slowness and physical inactivity. Multimorbidity was assessed using a simple disease count, based on 13 prevalent conditions. Disability was assessed by five activities of daily living; participants who had difficulty with one or more tasks were considered disabled. Differences among frail subpopulations were based on the co-presence of multimorbidity and disability. Differences among the following subpopulations were examined: 1) Non-frail (reference group); 2) Frail only; 3) Frail with disability; 4) Frailty with multimorbidity; 5) Frail with disability and multimorbidity. RESULTS: Frailty was present in 10.7% (n=473). Frailty was associated with increased risk for mortality (OR 1.40; 95% CI 1.15-1.69) and nursing home admission (OR 1.50; 95% CI 1.16-1.93); risks differed by subpopulations. Compared to the non-frail, the frail only group had poorer cognition and increased inflammation levels but did not have increased risk for mortality (OR 1.40; 95% CI 0.84-2.33) or nursing home admission (OR 1.01; 95% CI 0.46-2.21). Compared to the non-frail, the other frail subpopulations had significantly poorer cognition, increased inflammation levels, more white matter lesions, higher levels of calcium, glucose and red cell distribution width and increased risk for mortality and nursing home admission. CONCLUSIONS: The adverse health risks associated with frailty in the general older adult population may primarily be driven by increased disease burden and disability.

Polyunsaturated fatty acids in relation to incident mobility disability and decline in gait speed; the Age, Gene/Environment Susceptibility-Reykjavik Study.

BACKGROUND/OBJECTIVES: Low intake of long chain polyunsaturated fatty acids (PUFAs) are associated with physical disability; however, prospective studies of circulating PUFAs are scarce. We examined associations between plasma phospholipid n-3 and n-6 PUFAs with risk of incident mobility disability and gait speed decline. SUBJECTS/METHODS: Data are from a subgroup of the Age, Gene/Environment Susceptibility-Reykjavik Study, a population-based study of risk factors for disease and disability in old age. In this subgroup (n = 556, mean age 75.1 ± 5.0 years, 47.5% men), plasma phospholipid PUFAs were assessed at baseline using gas chromatography. Mobility disability and usual gait speed were assessed at baseline and after 5.2 ± 0.2 years. Mobility disability was defined as the following: having much difficulty, or being unable to walk 500 m or climb up 10 steps; decline in gait speed was defined as change ⩾ 0.10 m/s. Logistic regression analyses were performed to determine associations between sex-specific s.d. increments in PUFAs with risk of incident mobility disability and gait speed decline. Odds ratios (95% confidence intervals) adjusted for demographics, follow-up time, risk factors and serum vitamin D were reported. RESULTS: In women, but not men, every s.d. increment increase of total n-3 PUFAs and docosahexaenoic acid (DHA) was associated with lower mobility disability risk, odds ratio 0.48 (0.25; 0.93) and odds ratio 0.45 (0.24; 0.83), respectively. There was no association between n-6 PUFAs and the risk of incident mobility disability or gait speed decline. CONCLUSIONS: Higher concentrations of n-3 PUFAs and, particularly, DHA may protect women from impaired mobility but does not appear to have such an effect in men.

Effect of finite element model loading condition on fracture risk assessment in men and women: the AGES-Reykjavik study.

Proximal femoral (hip) strength computed by subject-specific CT scan-based finite element (FE) models has been explored as an improved measure for identifying subjects at risk of hip fracture. However, to our knowledge, no published study has reported the effect of loading condition on the association between incident hip fracture and hip strength. In the present study, we performed a nested age- and sex-matched case-control study in the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. Baseline (pre-fracture) quantitative CT (QCT) scans of 5500 older male and female subjects were obtained. During 4-7years follow-up, 51 men and 77 women sustained hip fractures. Ninety-seven men and 152 women were randomly selected as controls from a pool of age- and sex-matched subjects. From the QCT data, FE models employing nonlinear material properties computed FE-strength of the left hip of each subject in loading from a fall onto the posterolateral (FPL), posterior (FP) and lateral (FL) aspects of the greater trochanter (patent pending). For comparison, FE strength in stance loading (FStance) and total femur areal bone mineral density (aBMD) were also computed. For all loading conditions, the reductions in strength associated with fracture in men were more than twice those in women (p≤0.01). For fall loading specifically, posterolateral loading in men and posterior loading in women were most strongly associated with incident hip fracture. After adjusting for aBMD, the association between FP and fracture in women fell short of statistical significance (p=0.08), indicating that FE strength provides little advantage over aBMD for identifying female hip fracture subjects. However, in men, after controlling for aBMD, FPL was 424N (11%) less in subjects with fractures than in controls (p=0.003). Thus, in men, FE models of posterolateral loading include information about incident hip fracture beyond that in aBMD.

Age-related loss of proximal femoral strength in elderly men and women: the Age Gene/Environment Susceptibility Study--Reykjavik.

The risk of hip fracture rises rapidly with age, and is particularly high in women. This increase in fracture risk reflects both the age-related change in the risk of falling and decrements in the strength of the proximal femur. To better understand the extent to which proximal femoral density, structure and strength change with age as a function of gender, we have carried out a longitudinal analysis of proximal femoral volumetric quantitative computed tomographic (vQCT) images in men and women, analyzing changes in trabecular and cortical bone properties, and using subject-specific finite element modeling (FEM) to estimate changes in bone strength. In the AGES-Reykjavik Study vQCT scans of the hip were performed at a baseline visit in 2002-2006 and at a second visit 5.05±0.25 years later. From these, 223 subjects (111 men, 112 women, aged 68-87 years) were randomly selected. The subjects were evaluated for longitudinal changes in three bone variables assessed in a region similar to the total femur region quantified by DXA: areal bone mineral density (aBMD), trabecular volumetric bone mineral density (tBMD) and the ratio of cortical to total tissue volume (cvol/ivol). They were also evaluated for changes in bone strength using FEM models of the left proximal femur. Models were analyzed under single-limb stance loading (F(Stance)), which approximates normal physiologic loading of the hip, as well as a load approximating a fall onto the posterolateral aspect of the greater trochanter (F(Fall)). We computed five-year absolute and percentage changes in aBMD, tBMD, cvol/ivol, F(Fall) and F(Stance). The Mann-Whitney Test was employed to compare changes in bone variables between genders and the Wilcoxon Signed Rank Test was used to compare changes in bone strength between loading conditions. Multiple (linear) regression was employed to determine the association of changes in F(Fall) and F(Stance) with baseline age and five-year weight loss. Both men and women showed declines in indices of proximal femoral density and structure (aBMD: men -3.9±6.0%, women -6.1±6.2%; tBMD: men -14.8±20.3%, women -23.9±26.8%; cvol/ivol: men -2.6±4.6%, women -4.7±4.8%, gender difference: p<0.001). Both men and women lost bone strength in each loading condition (F(Stance): men -4.2±9.9%, women -8.3±8.5%; F(Fall): men -7.0±15.7%, women -12.8±13.2%; all changes from baseline p<0.0001). The gender difference in bone strength loss was statistically significant in both loading conditions (p<0.001 for F(Stance) and P<0.01 for F(Fall)) and F(Fall) was lost at a higher rate than F(Stance) in men (p<0.01) and women (p<0.0001). The gender difference in strength loss was statistically significant after adjustment for baseline age and weight loss in both loading conditions (p<0.01). In these multi-linear models, men showed increasing rates of bone loss with increasing age (F(Fall): p=0.002; F(Stance): p=0.03), and women showed increasing bone strength loss with higher degrees of weight loss (F(Stance): p=0.003). The higher loss of F(Fall) compared to F(Stance) supports previous findings in animal and human studies that the sub-volumes of bone stressed under normal physiologic loading are relatively better protected in aging. The gender difference in hip bone strength loss is consistent with the higher incidence of hip fracture among elderly women.

Effects of age and sex on the strength and cortical thickness of the femoral neck.

A group of 48 men (22 aged 65-75 years, 26 aged 80-90 years) and 59 women (32 aged 65-75 years, 27 aged 80-90 years) were enrolled in the Age, Gene/Environment Susceptibility-Reykjavik study and imaged with in vivo volumetric Quantitative Computed Tomography (QCT) to investigate the effects of age and sex on femoral neck structure and strength. Femoral neck cross-sectional moment of inertia for bending directions near those of standing and walking (I(AP)), bending strength (M(y)), and axial compressive strength (F(y)) were computed at the location of minimum cross-sectional area (minCSA). Local cortical thickness was computed in the inferior femoral neck based on density profiles extending through the cortex of the minCSA femoral neck section. Multivariate models accounting for height, weight, and age group (younger or older) showed that men had a 46% higher M(y) and a 23% higher F(y) than women, while women had a 13% thicker inferior cortex than men. Cortical thickness in the inferoposterior region of the femoral neck was significantly related to bending and axial strength after adjusting for overall volumetric bone mineral density. Both minCSA and I(AP) were higher in the older, gender-pooled age group, but F(y) and M(y) did not differ between the two age groups. The results suggest that age-related expansion of the femoral neck primarily occurs in the superior and inferior directions and helps maintain homeostasis of femoral neck stiffness and strength. The higher bending strength of the male femoral neck may partly explain why elderly men have a lower risk of hip fracture than elderly women.

Male-female differences in the association between incident hip fracture and proximal femoral strength: a finite element analysis study.

Hip fracture risk is usually evaluated using dual energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT) which provide surrogate measures for proximal femoral strength. However, proximal femoral strength can best be estimated explicitly by combining QCT with finite element (FE) analysis. To evaluate this technique for predicting hip fracture in older men and women, we performed a nested age- and sex-matched case-control study in the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. Baseline (pre-fracture) QCT scans of 5500 subjects were obtained. During 4-7 years follow-up, 51 men and 77 women sustained hip fractures. Ninety-seven men and 152 women were randomly selected as age- and sex-matched controls. FE-strength of the left hip of each subject for stance (F(Stance)) and posterolateral fall (F(Fall)) loading, and total femur areal bone mineral density (aBMD) were computed from the QCT data. F(Stance) and F(Fall) in incident hip fracture subjects were 13%-25% less than in control subjects (p ≤ 0.006) after controlling for demographic parameters. The difference between FE strengths of fracture and control subjects was disproportionately greater in men (stance, 22%; fall, 25%) than in women (stance, 13%; fall, 18%) (p ≤ 0.033), considering that F(Stance) and F(Fall) in fracture subjects were greater in men than in women (p < 0.001). For men, F(Stance) was associated with hip fracture after accounting for aBMD (p = 0.013). These data indicate that F(Stance) provides information about fracture risk that is beyond that provided by aBMD (p = 0.013). These findings support further exploration of possible sex differences in the predictors of hip fracture and of sex-specific strategies for using FE analysis to manage osteoporosis.

The timed 'Up & Go' is dependent on chair type.

INTRODUCTION: The timed 'Up & Go' (TUG) is a performance test identifying problems in functional mobility. More knowledge on how the type of chair used influences test results is needed. OBJECTIVE: To investigate inter-rater agreement on the time score and to assess if chair type used influenced the performance of the test. SETTING: (1) Inter-rater agreement investigation on the time score was carried out with elderly individuals living in a retirement home (n = 31). (2) Four types of chairs were tested on elderly individuals in three different health care centres (n = 100). RESULTS: The two observers were close in timing (mean difference = 0.04 s). From a reference chair the median time for TUG was 15.7 s compared with 16.9 s from a chair with a low seat (p < 0.001). It was significantly more difficult to stand up from a chair without armrests (p < 0.001), and from the lowest chair (p < 0.001), which was also the only chair difficult to sit down on (p = 0.02). CONCLUSION: The inter-rater agreement of the time scoring of the TUG has been confirmed. Test performance is dependent on chair type; chairs with armrests and a seating height of 44-47 cm should be used. Clinicians must follow standard procedures and equipment when using the test or else risk invalidating test findings.