Abdominal obesity and risk of hip fracture: a meta-analysis of prospective studies

Uptake of ox-LDL by binding to LRP6 mediates oxidative stress-induced BMSCs senescence promoting obesity-related bone loss

Obesity has long been thought to be a main cause of hyperlipidemia. As a systemic disease, the impact of obesity on organs, tissues and cells is almost entirely negative. However, the relationship between obesity and bone loss is highly controversial. On the one hand, obesity has long been thought to have a positive effect on bone due to increased mechanical loading on the skeleton, conducive to increasing bone mass to accommodate the extra weight. On the other hand, obesity-related metabolic oxidative modification of low-density lipoprotein (LDL) in vivo causes a gradual increase of oxidized LDL (ox-LDL) in the bone marrow microenvironment. We have reported that low-density lipoprotein receptor-related protein 6 (LRP6) acts as a receptor of ox-LDL and mediates the bone marrow stromal cells (BMSCs) uptake of ox-LDL. We detected elevated serum ox-LDL in obese mice. We found that ox-LDL uptake by LRP6 led to an increase of intracellular reactive oxygen species (ROS) in BMSCs, and N-acetyl-L-cysteine (NAC) alleviated the cellular senescence and impairment of osteogenesis induced by ox-LDL. Moreover, LRP6 is a co-receptor of Wnt signaling. We found that LRP6 preferentially binds to ox-LDL rather than dickkopf-related protein 1 (DKK1), both inhibiting Wnt signaling and promoting BMSCs senescence. Mesoderm development LRP chaperone (MESD) overexpression inhibits ox-LDL binding to LRP6, attenuating oxidative stress and BMSCs senescence, eventually rescuing bone phenotype.

Fat as a Friend or Foe of the Bone

PURPOSE OF REVIEW

The objective of this review is to summarize the literature on the prevalence and diagnosis of obesity and its metabolic profile, including bone metabolism, focusing on the main inflammatory and turnover bone mediators that better characterize metabolically healthy obesity phenotype, and to summarize the therapeutic interventions for obesity with their effects on bone health.

RECENT FINDINGS

Osteoporosis and fracture risk not only increase with age and menopause but also with metabolic diseases, such as diabetes mellitus. Thus, patients with high BMI may have a higher bone fragility and fracture risk. However, some obese individuals with healthy metabolic profiles seem to be less at risk of bone fracture. Obesity has become an alarming disease with growing prevalence and multiple metabolic comorbidities, resulting in a significant burden on healthcare and increased mortality. The imbalance between increased food ingestion and decreased energy expenditure leads to pathological adipose tissue distribution and function, with increased secretion of proinflammatory markers and harmful consequences for body tissues, including bone tissue. However, some obese individuals seem to have a healthy metabolic profile and may not develop cardiometabolic disease during their lives. This healthy metabolic profile also benefits bone turnover and is associated with lower fracture risk.

Relationships between obesity markers and bone parameters in community-dwelling older adults

BACKGROUND

Osteoporosis is an age-related condition that can lead to fragility fractures and other serious consequences. The literature data on the impact of obesity on bone health are contradictory. The main reasons for this discrepancy could be the imperfect nature of the body mass index (BMI) as a marker of obesity, the metabolic status (inflammation and metabolically healthy obesity), and/or heterogeneity in bone variables and architecture or sex.

AIMS

To examine the relationship between bone variables and three validated obesity criteria.

METHODS

In this cross-sectional study, participants were classified as obese according to their BMI, waist circumference (WC), and fat mass (FM). Bone variables and architecture were assessed using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, respectively.

RESULTS

One hundred sixty-eight adults aged 55 or over (men: 68%) were included. 48 (28%) participants were obese according to the BMI, with 108 (64%) according to the FM, and 146 (87%) according to the WC. Bone variables were positively correlated with WC and BMI (Pearson's r = 0.2-0.42). In men only, the obesity measures were negatively correlated with cortical bone density (Pearson's r = - 0.32 to - 0.19) and positively correlated with cortical bone area (Pearson's r = 0.22-0.39).

CONCLUSION

Our findings indicate that independent of sex and obesity criteria, when significant, being obese seems to lead to higher bone parameters than being non-obese, except for cortical bone density. Thus, in the obese population, assessing cortical density might help the physician to identify bone alteration. Further researches are needed to confirm our findings.

Improved femoral micro-architecture in adult male individuals with overweight: fracture resistance due to regional specificities

BACKGROUND

It is still unclear whether femoral fracture risk is positively or negatively altered in individuals with overweight. Considering the lack of studies including men with overweight, this study aimed to analyze regional specificities in mechano-structural femoral properties (femoral neck and intertrochanteric region) in adult male cadavers with overweight compared to their normal-weight age-matched counterparts.

METHODS

Ex-vivo osteodensitometry, micro-computed tomography, and Vickers micro-indentation testing were performed on femoral samples taken from 30 adult male cadavers, divided into the group with overweight (BMI between 25 and 30 kg/m2; n = 14; age:55 ± 16 years) and control group (BMI between 18.5 and 25 kg/m2; n = 16; age:51 ± 18 years).

RESULTS

Better quality of trabecular and cortical microstructure in the inferomedial (higher trabecular bone volume fraction, trabecular thickness, and cortical thickness, coupled with reduced cortical pore diameter, p < 0.05) and superolateral femoral neck (higher trabecular number and tendency to lower cortical porosity, p = 0.043, p = 0.053, respectively) was noted in men with overweight compared to controls. Additionally, the intertrochanteric region of men with overweight had more numerous and denser trabeculae, coupled with a thicker and less porous cortex (p < 0.05). Still, substantial overweight-induced change in femoral osteodensitometry parameters and Vickers micro-hardness was not demonstrated in assessed femoral subregions (p > 0.05).

CONCLUSIONS

Despite the absence of significant changes in femoral osteodensitometry, individuals with overweight had better trabecular and cortical femoral micro-architecture implying higher femoral fracture resistance. However, the microhardness was not significantly favorable in the individuals who were overweight, indicating the necessity for further research.

Effect of BMI-Discordant Abdominal Tissue Thickness on Fracture Probability: A Registry-Based Study

FRAX, which is used to assess fracture probability, considers body mass index (BMI), but BMI may not reflect individual variation in body composition and distribution. We examined the effect of BMI-discordant abdominal thickness on FRAX-derived fracture probability for major osteoporotic fracture (MOF) and hip fracture. We studied 73,105 individuals, mean age 64.2 years. During mean 8.7 years, 7048 (9.6%) individuals sustained incident MOF, including 2155 (3.0%) hip fractures. We defined abdominal thickness index (ATI) as the difference between abdominal thickness measured by dual-energy X-ray absorptiometry (DXA) and thickness predicted by BMI using sex-stratified regression. ATI was categorized from lower (<-2 cm, -2 to -1 cm) to higher (1-2 cm, >+2 cm) with referent around zero (-1 to +1 cm). Adjusted for FRAX probability, increasing ATI was associated with incident MOF and hip fracture (p < 0.001). For the highest ATI category, MOF risk was increased (hazard ratio [HR] = 1.23, 95% confidence interval [CI] 1.12-1.35) independent of FRAX probability. Similar findings were noted for hip fracture probability (HR = 1.28, 95% CI 1.09-1.51). There was significant age-interaction with much larger effects before age 65 years (HR = 1.44, 95% CI 1.23-1.69 for MOF; 2.29, 95% CI 1.65-3.18 for hip fracture). In contrast, for the subset of individuals with diabetes, there was also increased risk for those in the lowest ATI category (HR = 1.73, 95% CI 1.12-2.65 for MOF; 2.81, 95% CI 1.59-4.97 for hip fracture). Calibration plots across ATI categories demonstrated deviation from the line of identity in women (calibration slope 2.26 for MOF, 2.83 for hip fracture). An effect of ATI was not found in men, but this was inconclusive as the sex-interaction terms did not show significant effect modification. In conclusion, these data support the need to investigate increased abdominal thickness beyond that predicted by BMI and sex as a FRAX-independent risk factor for fracture. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Obesity and risk of fracture in postmenopausal women: a meta-analysis of cohort studies

BACKGROUND

Obesity is associated with an increased risk of fracture in adults, but is unclear in postmenopausal women. We aim to determine the association of obesity with the risk of fracture in postmenopausal women.

METHODS

PubMed, EMBASE, Cochrane Library and Web of Science were searched up to 11 April 2022 for cohort studies. And the included studies regarding the relationship between obesity with all cause of fracture in postmenopausal women were included in our meta-analysis. Data were screened and extracted independently by two reviewers. The relative risks (RR) were estimated using a random-effects model. Between-study heterogeneity was assessed using Cochran's Q and I² statistics.

RESULTS

Eight cohort studies comprising 671,532 postmenopausal women and 40,172 fractures were included. Overall, the pooling analysis shows that obesity in postmenopausal women is associated with an increased risk of all-cause fracture (relative ratio (RR) = 1.18; 95% confidence interval (CI):1.09-1.28, I² = 86.3%, p = .000). Sub-analyses for each site of fracture indicate that obesity was associated with an increased risk of vertebral fracture in postmenopausal women (RR = 1.154, 95% CI: 1.020-1.305, I² = 94.5%, p = .023), but reduced the risk of pelvic fracture (RR = 0.575, 95% CI:0.470-0.702, I² = 0.0%, p = .000). There is no statistically significant difference in the risk of hip and humerus fractures associated with obesity in postmenopausal women.

CONCLUSION

Obesity is associated with an increased risk of all-cause and vertebral fractures in postmenopausal women, but is a protective factor for pelvic fractures. Our findings suggest that postmenopausal women who regulate their weight might lower their risk of fractures.Registration: (PROSPERO: CRD42022324973)KEY MESSAGESObesity is associated with an increased risk of all-cause and vertebral fractures in postmenopausal women.Obesity maybe a protective factor for pelvic fractures in postmenopausal women.Postmenopausal women should regulate their weight to prevent fractures.

Association of Body Mass Index and Fracture Risk Varied by Affected Bones in Patients with Diabetes: A Nationwide Cohort Study

BACKGROUND

Body mass index (BMI) is a risk factor for the type 2 diabetes (T2DM), and T2DM accompanies various complications, such as fractures. We investigated the effects of BMI and T2DM on fracture risk and analyzed whether the association varied with fracture locations.

METHODS

This study is a nationwide population-based cohort study that included all people with T2DM (n=2,746,078) who received the National Screening Program during 2009-2012. According to the anatomical location of the fracture, the incidence rate and hazard ratio (HR) were analyzed by dividing it into four categories: vertebra, hip, limbs, and total fracture.

RESULTS

The total fracture had higher HR in the underweight group (HR, 1.268; 95% CI, 1.228 to 1.309) and lower HR in the obese group (HR, 0.891; 95% CI, 0.882 to 0.901) and the morbidly obese group (HR, 0.873; 95% CI, 0.857 to 0.89), compared to reference (normal BMI group). Similar trends were observed for HR of vertebra fracture. The risk of hip fracture was most prominent, the risk of hip fracture increased in the underweight group (HR, 1.896; 95% CI, 1.178 to 2.021) and decreased in the obesity (HR, 0.643; 95% CI, 0.624 to 0.663) and morbidly obesity group (HR, 0.627; 95% CI, 0.591 to 0.665). Lastly, fracture risk was least affected by BMI for limbs.

CONCLUSION

In T2DM patients, underweight tends to increase fracture risk, and overweight tends to lower fracture risk, but association between BMI and fracture risk varied depending on the affected bone lesions.

Associations of abdominal obesity with different types of bone fractures in adults: A systematic review and dose-response meta-analysis of prospective cohort studies

Findings on the association between abdominal obesity and hip fracture were summarized in a meta-analysis in 2017; however, no study has examined the dose-response association between abdominal fat indices and hip fracture. Also, we found no meta-analysis investigating other types of bone fractures including any vertebral fractures in relation to abdominal obesity. Therefore, the present systematic review and dose-response meta-analysis of prospective cohort studies were conducted to examine the association between abdominal obesity and different types of bone fractures. A comprehensive literature search was done by searching PubMed, Scopus, Web of Science, and Google Scholar until October 2021. In total, 23 articles from prospective cohort studies with a total sample size of 3,456,631 participants were included. During the follow-up periods ranging between 4 and 26 years, 137,989 cases of bone fracture were recorded. After comparing the highest and lowest categories of abdominal fat indices, the summary relative risks (RRs) of any, hip, and vertebral fractures were 0.99 (95% CI: 0.81-1.20), 1.09 (95% CI: 0.82-1.43), and 1.18 (95% CI: 1.05-1.33), respectively, indicating a significant positive association between abdominal obesity and risk of vertebral fracture. In the non-linear dose-response analysis, abdominal obesity based on the waist-to-hip ratio (WHR) was positively associated with an increased risk of hip fracture from 0.7 to 1.1 units of WHR. In the linear analysis, a 10 cm increase in waist circumference (WC) was associated with a 3% higher risk of vertebral fracture. We found no other dose-response association for other types of bone fractures. In conclusion, abdominal obesity may be associated with a higher risk of hip and vertebral fractures.

Association between Wrist Circumference and Risk of Any Fracture in Adults: Findings from 15 Years of Follow-Up in the Tehran Lipid and Glucose Study

We evaluated whether wrist circumference (WrC), as a novel anthropometric measure, is associated with incidences of any fractures. The study population included 8288 adults (45.3% men) aged ≥30 years, who were followed for incidences of any fractures from 31 January 1999 to 16 March 2016. We used Cox proportional hazard models adjusted for well-known risk factors to evaluate the association of WrC, both as continuous and categorical variables (bottom tertile as reference), with incidences of any fractures and major osteoporotic fractures (MOF). Over 15 years of follow-ups, 348 fractures occurred (men = 162). For a 1 cm increase in WrC, hazard ratios (HRs) were 1.18 (95% CI: 1.03-1.35) for incident any fractures and 1.22 (1.01-1.49) for incident MOF. In addition to WrC, age, female sex, lower BMI, higher WC, current smoking, and usage of steroidal medications were significantly associated with the incidences of any fractures. Moreover, participants in the middle and top tertiles of WrC had a higher risk of incidence for any fractures [HR = 1.62 (1.19-2.20) and 1.70 (1.14-2.55), respectively, p-value for trend = 0.012]. We presented WrC as a strong and independent risk factor for incidences of any fractures that might be considered in the risk prediction of bone fracture in Iranian adults.

Bone, fat, and muscle interactions in health and disease

Energy metabolism is a point of integration among the various organs and tissues of the human body, not only in terms of consumption of energy substrates but also because it concentrates a wide interconnected network controlled by endocrine factors. Thus, not only do tissues consume substrates, but they also participate in modulating energy metabolism. Soft mesenchymal tissues, in particular, play a key role in this process. The recognition that high energy consumption is involved in bone remodeling has been accompanied by evidence showing that osteoblasts and osteocytes produce factors that influence, for example, insulin sensitivity and appetite. Additionally, there are significant interactions between muscle, adipose, and bone tissues to control mutual tissue trophism. Not by chance, trophic and functional changes in these tissues go hand in hand from the beginning of an individual's development until aging. Likewise, metabolic and nutritional diseases deeply affect the musculoskeletal system and adipose tissue. The present narrative review highlights the importance of the interaction of the mesenchymal tissues for bone development and maintenance and the impact on bone from diseases marked by functional and trophic disorders of adipose and muscle tissues.

Effect of obesity on fragility fractures, BMD and vitamin D levels in postmenopausal women. Influence of type 2 diabetes mellitus

AIMS

To see the effects of obesity on risk fracture, bone density (BMD), and vitamin D levels in a group of postmenopausal women, and consider how comorbid type 2 diabetes mellitus (T2DM) modifies them.

METHODS

679 postmenopausal women were grouped into obese and non-obese. Obese women were grouped into those with T2DM and those without. 25(OH)-vitamin D, PTH and BMD were measured, and prevalent fragility fractures were gathered.

RESULTS

Obese women had higher prevalence of T2DM, than non-obese women. Levels of 25(OH)-vitamin D were lower and those of PTH higher in obese women, BMD values were higher in obese women. Diabetic-obese women had a higher prevalence of non-vertebral fractures than non-diabetic-obese. Multivariate logistic regression model showed association of fragility fractures with age, total hip BMD, BMI and T2DM. Obese women have higher BMD and lower 25(OH)-vitamin D values (and higher PTH) than non-obese, without diabetes.

CONCLUSIONS

T2DM confers an increased risk of non-vertebral fractures in postmenopausal obese women.

Weight change and the risk of hip fractures in patients with type 2 diabetes: a nationwide cohort study

Both weight gain and weight loss in type 2 diabetic population were associated with increased risk of hip fracture, while maintaining weight lowered the risk of hip fracture. Regarding the risk of hip fracture, we can propose active monitoring to maintain the weight of type 2 diabetes patients.

INTRODUCTION

In type 2 diabetes, patients are often asked to control their weight in order to reduce their diabetic morbidity. The American Diabetes Association recommends that diabetic patients conduct high-intensity interventions for regulating diet, physical activity, and behavior to reduce weight, followed by long-term comprehensive weight maintenance programs. Although such weight control attempts are required in diabetic patients, there are few studies on the effect of weight change on hip fracture in this population. We aim to investigate the association between body weight change and the incidence of hip fracture in subjects with type 2 diabetes using large-scale, nationwide cohort data on the Korean population.

MATERIALS AND METHODS

A total of 1,447,579 subjects (894,204 men and 553,375 women) > 40 years of age, who were diagnosed with type 2 diabetes, were enrolled in this study. Weight change within 2 years was divided into five categories: from weight loss ≥ 10% to weight gain ≥ 10%. The hazard ratios (HRs) and 95% confidence intervals for the incidence of hip fracture were analyzed, compared with the reference of the stable weight group (weight change < 5%).

RESULTS

Among 5 weight change groups, more than 10% weight loss showed the highest HR (HR, 1.605; 95% CI, 1.493 to 1.725), followed by more than 10% weight gain (HR, 1.457; 95% CI, 1.318 to 1.612). The effect of weight change on hip fracture risk was greater in males than in females, and those under 65 years of age were greater than those over 65 years of age. Baseline BMI did not play a role of weight change affecting the risk of hip fracture. The HR for hip fracture of subjects with regular exercise was lower than those without regular exercise.

CONCLUSIONS

In the type 2 diabetes population, both weight gain and weight loss were significantly associated with a higher risk of hip fracture, whereas maintaining body weight reduced the risk of hip fracture the most.

Obesity and Bone Health: A Complex Relationship

Recent scientific evidence has shown an increased risk of fractures in patients with obesity, especially in those with a higher visceral adipose tissue content. This contradicts the old paradigm that obese patients were more protected than those with normal weight. Specifically, in older subjects in whom there is a redistribution of fat from subcutaneous adipose tissue to visceral adipose tissue and an infiltration of other tissues such as muscle with the consequent sarcopenia, obesity can accentuate the changes characteristic of this age group that predisposes to a greater risk of falls and fractures. Other factors that determine a greater risk in older subjects with obesity are chronic proinflammatory status, altered adipokine secretion, vitamin D deficiency, insulin resistance and reduced mobility. On the other hand, diagnostic tests may be influenced by obesity and its comorbidities as well as by body composition, and risk scales may underestimate the risk of fractures in these patients. Weight loss with physical activity programs and cessation of high-fat diets may reduce the risk. Finally, more research is needed on the efficacy of anti-osteoporotic treatments in obese patients.

General and abdominal obesity operate differently as influencing factors of fracture risk in old adults

To infer the causality between obesity and fracture and the difference between general and abdominal obesity, a prospective study was performed in 456,921 participants, and 10,142 participants developed an incident fracture with follow-up period of 7.96 years. A U-shape relationship was observed between BMI and fracture, with the lowest risk of fracture in overweight participants. The obesity individuals had higher fracture risk when BMD was adjusted, and the protective effect of moderate-high BMI on fracture was mostly mediated by bone mineral density (BMD). However, for abdominal obesity, the higher WCadjBMI (linear) and HCadjBMI (J-shape) were found to be related to higher fracture risk, and less than 30% of the effect was mediated by BMD. By leveraging genetic instrumental variables, it provided additional evidences to support the aforementioned findings. In conclusion, keeping moderate-high BMI might be of benefit to old people in terms of fracture risk, whereas abdominal adiposity might increase risk of fracture.

The relationship between central obesity and bone mineral density: a Mendelian randomization study

BACKGROUND

The relationship between obesity and osteoporosis is an important public health issue. The goal of this study was to investigate whether and to what extent central obesity traits affect bone mineral density (BMD).

METHODS

We conducted a two-sample Mendelian randomization analysis. Genomewide significant single nucleotide polymorphisms associated with waist circumference, hip circumference, waist-to-hip ratio, waist circumference adjusted by body mass index (WCadjBMI), hip circumference adjusted by BMI (HCadjBMI) and waist-to-hip ratio adjusted by BMI (WHRadjBMI) were obtained from a large-scale database containing 224,459 samples. The BMD summary dataset was obtained from a UK Biobank database including 265,627 participants.

RESULTS

The results provided strong evidence that the HCadjBMI trait was causally and negatively associated with BMD (β: - 0.135, 95% CI - 0.216 to - 0.054; P = 0.001), while the WHR trait was causally and positively associated with BMD (β: 0.194, 95% CI 0.062 to 0.325, P = 0.004). No significant effects were observed for other traits on BMD.

CONCLUSIONS

This study indicates variations in the abilities of different central obesity traits to influence BMD. These results should be considered in further studies and public health measures on obesity and osteoporosis prevention strategies.

Influence of Obesity on Bone Turnover Markers and Fracture Risk in Postmenopausal Women

Background and aims: The relationship between obesity and bone metabolism is controversial. In recent decades, the protective role of obesity in the development of osteoporosis is questioned. The aims of this study are the following: to evaluate the differences in bone turnover markers between postmenopausal women with and without obesity and to compare the risk of fracture at five years between these groups. Methods: An observational longitudinal prospective cohort study of postmenopausal women with obesity (O) (body mass index (BMI) > 30 kg/m2) and non-obesity (NoO) (BMI < 30 kg/m2) is designed. 250 postmenopausal women are included in the study (NoO: 124 (49.6%) and O: 126 (50.4%)). It measures epidemiological variables, dietary variables (calcium intake, vitamin D intake, smoking, alcohol consumption, and physical activity), biochemicals (β-crosslap, type I procollagen amino-terminal peptide (P1NP), 25OH-vitamin D, and parathyroid hormone (PTH)), anthropometric variables, and fracture data five years after the start of the study. The mean age is 56.17 (3.91) years. Women with obesity showed lower levels of vitamin D (O: 17.27 (7.85) ng/mL, NoO: 24.51 (9.60) ng/mL; p < 0.01), and higher levels of PTH (O: 53.24 (38.44−65.96) pg/mL, NoO: 35.24 (25.36−42.40) pg/mL; p < 0.01). Regarding the bone formation marker (P1NP), it was found to be high in women without obesity, O: 45.46 (34.39−55.16) ng/mL, NoO: 56.74 (45.34−70.74) ng/mL; p < 0.01; the bone resorption marker (β-crosslap) was found to be high in women with obesity, being significant in those older than 59 years (O: 0.39 (0.14) ng/mL, NoO 0.24 (0.09) ng/mL; p < 0.05). No differences are observed in the risk of fracture at 5 years based on BMI (OR = 0.90 (95%CI 0.30−2.72); p = 0.85). Conclusions: Postmenopausal women with obesity showed lower levels of bone formation markers; older women with obesity showed higher markers of bone resorption.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Adipose Tissue Dysfunction: Impact on Bone and Osseointegration

Bone metabolism may be adversely affected in metabolic diseases such as obesity and metabolic syndrome, which are characterised by weight gain, due to the expansion of adipose tissue deposits. As an important regulator of energy metabolism, adipose tissues synthesise and secrete several key regulatory adipokines that influence a range of metabolic functions. This narrative review outlines the evidence for the mechanisms by which adipose tissue dysfunction may alter bone metabolism prior to the development of frank hyperglycaemia and presents the emerging evidence for the impact of diet-induced expansion of adipose tissue on implant osseointegration. Successful osseointegration requires normal bone cell function, and the expansion of adipose tissue deposits results in dysregulated adipokine production favouring an increase in pro-inflammatory adipokines, contributing to the development of a chronic inflammatory state and insulin resistance. The increase in inflammatory cytokines promotes the growth and differentiation of osteoclasts indirectly through the modulation of osteoblastic RANKL production and directly by reducing osteoclast apoptosis and increased osteoclastic expression of RANK. Conversely, the suppression of osteoblastic regulatory genes results in reduced osteoblast numbers and function contributing to compromised bone turnover. Compromised osseointegration has been established in hyperglycaemia; however, as discussed in this review, it may not be the only driver of altered bone metabolism. The incidence of metabolic disease in the community is rising, patients may present for implant treatment with undiagnosed, underlying changes to bone cell metabolism due to adipose tissue dysmetabolism.

Relationship between abdominal obesity (based on waist circumference) and serum vitamin D levels: a systematic review and meta-analysis of epidemiologic studies

CONTEXT

Although previous observational studies have investigated the association between waist circumference (WC) values and serum vitamin D levels, findings have been inconsistent.

OBJECTIVE

A systematic review and meta-analysis was performed to evaluate the effect of abdominal obesity (based on WC) on vitamin D deficiency or insufficiency in adults.

DATA SOURCES

A systematic search of the published literature up to September 2020 was conducted in electronic databases, including MEDLINE (PubMed), EMBASE, Institute for Scientific Information (ISI) (Web of Science), Scopus, and Google Scholar, for observational studies that investigated the association between abdominal obesity (based on WC) or different categories of WC as the exposure and serum 25-hydroxy vitamin D levels as the outcome.

DATA EXTRACTION

Eighteen cross-sectional studies were included in the review. The relationship between WC values and combined serum vitamin D deficiency and insufficiency (<30 ng/mL) or vitamin D deficiency (<20 ng/mL) was evaluated.

DATA ANALYSIS

Combining 8 effect sizes from 5 investigations, including 7997 individuals, illustrated that the highest category of WC, compared with the lowest category of WC, was related to 82% increased odds of combined serum vitamin D deficiency and insufficiency (<30 ng/mL) (OR: 1.82; 95% CI: 1.34, 2.49). Moreover, in studies that investigated both genders together, the highest category of WC, compared with the lowest category of WC, was associated with 61% increased odds of serum vitamin D deficiency (<20 ng/mL) (OR: 1.61; 95% CI: 1.12, 2.31). The same results were obtained for almost all subgroups for several covariates.

CONCLUSION

This meta-analysis of cross-sectional studies confirmed that increased WC was related to the elevated risk of combined vitamin D deficiency and insufficiency in adults. More prospective studies are needed to confirm causality.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020190485.

Sex-specific incidence rates and risk factors for fracture: A 16-year follow-up from the Tehran lipid and glucose study

OBJECTIVE

To examine the population-based incidence of any-fracture and its potential risk factors in a sex-split cohort of the Iranian population.

MATERIALS AND METHODS

A total of 3477 men and 4085 women with a mean (SD) age of 47.92(13.1) and 45.88(11.47) years, respectively were entered into the study. The age-standardized incidence rates per 100,000 person-years were reported for the whole population and each sex separately. Cox proportional hazard models were used to estimate hazard ratios (HR) for potential risk factors. Only fractures requiring inpatients' care were considered as the outcome. We also defined major osteoporotic fractures (MOF) as the composite of the fractures that occurred in the vertebral, wrist, hip and pelvic sites among population aged ≥50 years.

RESULTS

During the median (IQR) follow-up of 15.9 years, 4.34%men and 3.75% women experienced at least one incident any-fracture. The annual age-standardized incidence rates (95% CI) among men and women were 330.9 (279.6-388.9) and 319.4(268.1-377.3) per 100,000 person-years, respectively; the corresponding values for incidence of MOF was 202.2(142.3-278.6) in men and 342.1(260.4-441.0) per 100,000 person-years for women. In the multivariable model, among the whole population, age groups ≥50 years, central obesity [HR: 95% CI 1.77(1.32-2.39)], current smoking [1.59(1.15-2.20)] and using steroid medications [2.20(1.04-4.67)] significantly increased the risk of incident fracture (all P < 0.05); however the impact of the first two risk factors were more prominent among women (P for interaction ≤0.01). Moreover, being obese was associated with a lower risk of incident first fracture in the total population [HR: 95% CI: 0.61(0.40-0.92)]. Being men [HR: 95% CI: 0.54(0.30-0.99)] and prediabetes status [HR: 95% CI: 0.53(0.30-0.95)] were also associated with lower risk for MOF.

CONCLUSION

This is the first report of long-term incidence rate of any-fracture and MOF conducted in the metropolitan city of Tehran. Among modifiable risk factors of fracture, in the whole population smoking habit and using steroid medications and particularly for women central obesity should be considered as main risk factors for preventive strategies. Prediabetes status was associated with lower risk of MOF.

Impact of waist circumference on the risk of vertebral fracture: A nationwide cohort study in South Korea

Evidence on the association between abdominal obesity and vertebral fracture (VF) risk is limited. We examined the association of waist circumference (WC) and abdominal obesity with VF risk in 352,095 South Korean participants aged ≥40 years who underwent health checkups between 2009 and 2012. Abdominal obesity was defined by WC ≥90 cm in men and ≥ 85 cm in women according to the Asian-specific WC cutoff for abdominal obesity. Participants were a representative sample cohort of the Korean National Health Insurance System. The hazard ratios (HRs) and 95% CIs of VF development were determined using multivariable Cox proportional hazard regression analysis. During the 5.5 years of follow-up, there were 2030 and 4968 new cases of VF in men and women, respectively. In men, those with abdominal obesity showed an elevated HR (1.11, 95% CI: 1.01-1.23) of incident VF than did those without abdominal obesity. In women, the HRs of VF increased in higher WC groups after adjusting for confounders (P for trend <0.001); the HR decreased in those with WC <75.0 cm (HR: 0.81, 95% CI: 0.75-0.88) and increased in those with WC 85.0-89.9 cm (HR: 1.12, 95% CI: 1.02-1.22), 90.0-94.9 cm (HR: 1.19, 95% CI: 1.08-1.32), and ≥ 95.0 cm (HR: 1.27, 95% CI: 1.12-1.43) compared with those with WC 80.0-84.9 cm. This association persisted after stratification by age in women. WC and abdominal obesity were positively associated with VF risk in women, and abdominal obesity was associated with VF risk even in men. The consideration of WC and controlling abdominal obesity may be helpful in reducing future VF risk.

Differential impact of osteoporosis, sarcopenia and obesity on physical performance in aging men

PURPOSE

Aging and concurrent constitutional changes as sarcopenia, osteoporosis and obesity are associated with progressive functional decline. Coincidence and mutual interference of this risk factors require further evaluation.

METHODS

Cross-sectional evaluation of musculoskeletal health in a community-dwelling cohort of men aged 65-90 years. Objectives included descriptive analysis of age-related decline in physical performance, prevalence of osteoporosis (FRAX-Score), sarcopenia (EWGSOP criteria) and obesity (BMI > 30 kg/m2) and their coincidence/interference.

RESULTS

Based on 507 participants assessed, aging was associated with progressive functional deterioration, regarding power (chair rise test -1.54% per year), performance (usual gait speed -1.38% per year) and muscle force (grip strength -1.52% per year) while muscle mass declined only marginally (skeletal muscle index -0.29% per year). Prevalence of osteoporosis was 41.8% (n = 212) while only 22.9% (n = 116) of the participants met the criteria for sarcopenia and 23.7% (n = 120) were obese. Osteosarcopenia was found in n = 79 (15.6%), sarcopenic obesity was present in 14 men (2.8%). A combination of all three conditions could be confirmed in n = 8 (1.6%). There was an inverse correlation of BMI with physical performance whereas osteoporosis and sarcopenia did not interfere with functional outcomes.

CONCLUSION

Based on current definitions, there is considerable overlap in the prevalence of osteoporosis and sarcopenia, while obesity appears to be a distinct problem. Functional decline appears to be associated with obesity rather than osteoporosis or sarcopenia. It remains to be determined to what extend obesity itself causes performance deficits or if obesity is merely an indicator of insufficient activity eventually predisposing to functional decline.

Association between Bone Mineral Density and Nutritional Status, Body Composition and Bone Metabolism in Older Adults

PURPOSE

To identify an association between bone mineral density (BMD) and nutritional status, body composition and bone metabolism in older patients.

METHODS

Cross-sectional study, involving older adults, with osteopenia/osteoporosis and with normal BMD. The mineral density of the lumbar spine from L1 to L4 and the proximal region of the femur was assessed using dual energy X-ray absorptiometry. Biochemical analyzes were performed of 25(OH)-D, calcium and parathormone. Weight, knee height, and abdominal (AC), mid-upper arm (MUAC) and calf (CC) circumferences were measured. The percentage of body fat (%BF) and Fat-Free Mass (FFM) were quantified by electrical bioimpedance analysis. The Body Mass Index (BMI) was calculated. The statistical analysis used bivariate and multivariate, parametric and/or non-parametric tests, and was considered significant when p <0.05.

RESULTS

Of the total 51 older adults assessed, 30 of them (58.8%) were diagnosed with osteopenia/osteoporosis. Body weight (p = 0.001), BMI (p = 0.001), % BF (p = 0.030) and serum concentrations of 25(OH)-D (p = 0.003) were higher in the group without changes in BMD. BMI and serum levels of 25(OH)-D demonstrated a positive correlation with the BMD of all bone compartments and the AC displayed a positive correlation with the lumbar vertebrae. In the logistic regression models, adjusted for sex and age, the BMI and the serum concentration of 25(OH)-D were presented as a protective factor against osteopenia/osteoporosis.

CONCLUSIONS

Higher body weight, BMI, AC and %BF, and sufficient serum levels of vitamin D, were shown to be promoters of BMD.

Adiposity Without Obesity: Associations with Osteoporosis, Sarcopenia, and Falls in the Healthy Ageing Initiative Cohort Study

OBJECTIVE

Obesity is commonly defined by BMI rather than adiposity, which may have differential effects on musculoskeletal health. Musculoskeletal outcomes were compared in older adults with normal adiposity and normal BMI (NA-NBMI), those with high adiposity but normal BMI (HA-NBMI), and those with high adiposity and high BMI (HA-HBMI).

METHODS

In 3,411 70-year-olds, obesity was defined as BMI ≥ 30 kg/m² and adiposity as body fat percentage ≥ 25% (men) or ≥ 35% (women) from dual-energy x-ray absorptiometry. Bone parameters were measured by dual-energy x-ray absorptiometry and peripheral quantitative computed tomography. Sarcopenia was defined as low handgrip strength with or without low appendicular lean mass. Falls were self-reported 6 and 12 months later.

RESULTS

Prevalence of NA-NBMI, HA-NBMI, and HA-HBMI was 14.2%, 68.1%, and 17.7%, respectively. Compared with HA-HBMI, HA-NBMI had increased likelihood for sarcopenia (adjusted odds ratio: 3.99; 95% CI: 1.41-11.32) and osteoporosis (2.91; 95% CI: 2.35-3.61) but similar likelihood of falls (P > 0.05). HA-NBMI had lower values for bone geometry parameters, as well as grip strength, than both NA-NBMI and HA-HBMI (all P < 0.05).

CONCLUSIONS

High adiposity without high BMI is more common than BMI-defined obesity in older Swedish adults but does not provide similar protection from osteoporosis and sarcopenia.

Systematic review and meta-analysis of the association between dairy consumption and the risk of hip fracture: critical interpretation of the currently available evidence

In the present meta-analysis, reductions in the risk of hip fracture with milk consumption were only observed among American adults, but not among Scandinavian adults, possibly because milk products are more commonly fortified with vitamin D in the former population than in Scandinavian countries. The reduction in the risk of hip fracture was also observed with yogurt consumption, which is often associated with healthy lifestyles and dietary patterns that contribute to improved bone health.

INTRODUCTION

Although dairy products contain bone-beneficial nutrients, the association between dairy consumption and the risk of hip fracture remains equivocal. Fueling this uncertainty, the elevated risk of hip fracture in association with milk consumption was observed in a cohort of Swedish women. A systematic review and meta-analysis of prospective cohort studies was performed to critically evaluate the association, or lack thereof, between dairy consumption (milk, yogurt, and cheese) and the risk of hip fracture.

METHODS

A random effects model was used to generate the summary relative risks (RRs) with their 95% confidence intervals (CIs) for the associations of interest.

RESULTS

In the meta-analysis of the highest versus lowest category of consumption, higher consumption of yogurt (RR 0.78, 95% CI 0.68, 0.90), but not milk (RR 0.86, 95% CI 0.73, 1.02) or cheese (RR 0.85, 95% CI 0.66, 1.08), was associated with a lower risk of hip fracture. For milk, the reduced risk of fracture with higher milk consumption was observed in the USA (RR 0.75, 95% CI 0.65, 0.87), but not in Scandinavian countries (RR 1.00, 95% CI 0.85, 1.17). These findings were further supported by the fact that American studies (RR 0.93, 95% CI 0.88, 0.98; per 1 glass/day), but not Scandinavian studies (RR 1.01, 95% CI 0.95, 1.07; per 1 glass/day), demonstrated a linear association between milk consumption and the risk of hip fracture.

CONCLUSIONS

The cumulative evidence from prospective cohort studies reassuringly suggests that the risk of hip fracture may not be elevated among people who consume milk, yogurt, and cheese, and that a greater consumption of milk or yogurt may even be associated with a lower risk of hip fracture depending on the factors that may differ across the population of interest.

Association between abdominal obesity and fragility fractures among elderly Israeli women

BACKGROUND

Obesity has been traditionally viewed as a protective factor for fractures. Recent studies have challenged this concept, particularly regarding abdominal obesity. We aimed to investigate the association between abdominal obesity, body mass index (BMI) and fragility fractures prevalence in a sample of community-dwelling elderly Israeli women.

METHODS

The data in this cross-sectional study were based on 'Mabat Zahav'-a survey of a nationally representative sample of elderly Israelis. The study population included 669 women. Data on fragility fractures site and circumstances were self-reported, and height, weight, waist and calf circumferences were measured. Waist circumference (WC) variable was divided into tertiles: < 88 cm, 88-99 cm and > 99 cm.

RESULTS

Sixty-five women reported fragility fractures (14 hip fractures, 18 vertebral fractures and 39 wrist fractures). Mean age was 73.9 ± 5.9 years, mean BMI was 29.9 ± 5 kg/m² and mean WC was 93.9 ± 12 cm. While BMI was not associated with osteoporotic fractures, abdominal obesity (WC > 88 cm) was positively associated with fragility fractures, independently of age, smoking, physical activity [middle and high WC tertiles {3.15 (95% CI 1.41-7.02), 2.78 (95% CI 1.05-7.31), respectively}].

CONCLUSIONS

Among this sample of elderly women, abdominal obesity was positively associated with fragility fractures, independently of age, smoking, physical activity and BMI. Waist circumference, an easily measured anthropometric indicator, may be useful for assessing the risk of fragility fractures in elderly women, particularly among those with normal or high BMI-a vast population which has been traditionally considered as having lower fracture risk.

Accelerometer-based prediction of skeletal mechanical loading during walking in normal weight to severely obese subjects

There is no objective way to monitor mechanical loading characteristics during exercise for bone health improvement. We developed accelerometry-based equations to predict ground reaction force (GRF) and loading rate (LR) in normal weight to severely obese subjects. Equations developed had a high and moderate accuracy for GRF and LR prediction, respectively, thereby representing an accessible way to determine mechanical loading characteristics in clinical settings.

INTRODUCTION

There is no way to objectively prescribe and monitor exercise for bone health improvement in obese patients based on mechanical loading characteristics. We aimed to develop accelerometry-based equations to predict peak ground reaction forces (pGRFs) and peak loading rate (pLR) on normal weight to severely obese subjects.

METHODS

Sixty-four subjects (45 females; 84.6 ± 21.7 kg) walked at different speeds (2-6 km·h^-1) on a force plate-equipped treadmill while wearing accelerometers at lower back and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland-Altman plots. Actual and predicted values at different speeds were compared by repeated measures ANOVA.

RESULTS

Body mass and peak acceleration were included for pGRF prediction and body mass and peak acceleration transient rate for pLR prediction. All pGRF equation coefficients of determination were above 0.89, a good agreement between actual and predicted pGRFs, with a mean absolute percent error (MAPE) below 6.7%. No significant differences were observed between actual and predicted pGRFs at each walking speed. Accuracy indices from our equations were better than previously developed equations for normal weight subjects, namely a MAPE approximately 3 times smaller. All pLR prediction equations presented a lower accuracy compared to those developed to predict pGRF.

CONCLUSION

Walking pGRF and pLR in normal weight to severely obese subjects can be predicted with moderate to high accuracy by accelerometry-based equations, representing an easy and accessible way to determine mechanical loading characteristics in clinical settings.

Visceral Fat Is a Negative Determinant of Bone Health in Obese Postmenopausal Women

The protective effect of obesity on bone health has been challenged by studies that link visceral adiposity to poor bone microarchitecture in young obese men and women. In postmenopausal women, the role of visceral adipose tissue (VAT) on bone turnover markers (BTMs) has not been investigated. The aim was to investigate the impact of VAT on BTMs, total bone mineral density (BMD), vitamin D metabolites and parathyroid levels (1-84 PTH) levels in postmenopausal women. A total of 76 lean and overweight women (without osteoporosis) underwent VAT measurements by dual-energy X-ray absorptiometry (iDXA). Blood samples were analyzed for serum C-terminal telopeptide of type 1 collagen (CTX-1), osteocalcin, bone-specific alkaline phosphatase (bone ALP), 1–84 PTH and vitamin D (25 hydroxyvitamin D, 25(OH)D) levels. VAT volumes ranged from 91 to 3392 cm³ and body mass index (BMI) ranged from 18.3 to 53.9 kg/m². Women in the highest VAT quartile had significantly lower CTX-1, 25(OH)D, osteocalcin and the highest BMD (p < 0.05, for all). While VAT positively associated with BMD, after controlling for BMI, VAT was a negative predictor of BMD (β = 0.368, p < 0.05). VAT was an independent negative predictor of CTX-1 (β = −0.263, p < 0.05) and osteocalcin levels (β = −0.277, p < 0.05). Among all measures of adiposity, VAT was the strongest independent determinant of BMD and BTMs. In clinical settings, VAT, and not BMI, may be a sensitive predictor of bone health in obese women.

Consumption of nutrients and insulin resistance suppress markers of bone turnover in subjects with abdominal obesity

OBJECTIVE

Abdominal obesity and type 2 diabetes are associated with insulin resistance and low bone turnover along with an increased fracture risk. The mode of action is poorly understood. The bone resorption marker, C-terminal telopeptide type 1 collagen (CTX), and to a lesser extent, the bone formation marker, Procollagen type 1 N-terminal propeptide (P1NP) appear to be inhibited by food consumption. The link between food consumption, insulin resistance and bone turnover remains to be clarified. Primarily we aimed to compare the postprandial CTX, P1NP and PTH responses by two frequently applied methods in assessing metabolic health; oral glucose tolerance test (OGTT) and mixed meal tolerance test. Secondly, we explored the effect of insulin resistance on bone marker responses.

METHODS

We enrolled 64 subjects with abdominal obesity. Following 10 h of fasting, subjects initially underwent a standard OGTT (300 kcal) and approximately one week later a mixed meal tolerance test (1130 kcal). Circulating CTX, P1NP and PTH were assessed on both days at time = 0, after 30 min and after 90 min for comparison of the two interventions. We analyzed glucose and insulin levels for the assessment of insulin resistance. Additionally, we measured plasma calcium levels along with the gut hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like-peptide 2 (GLP-2) in an attempt to identify possible mediators of the postprandial bone response.

RESULTS

CTX, P1NP and PTH were suppressed by OGTT and the mixed meal; the latter induced a more pronounced suppression after 90 min. Calcium levels were similar between OGTT and meal. GIP and GLP-2 levels increased after both interventions, although only the meal induced a sustained increase after 90 min. Fasting P1NP was inversely associated with insulin resistance. The meal-induced suppression of P1NP (but not CTX or PTH) was inversely associated with level of insulin resistance.

CONCLUSION

The acute postprandial suppression of bone turnover markers is extended after ingestion of a mixed meal compared to an OGTT. The response appears to be independent of gender and prompted by a reduction in PTH. The study additionally indicates a possible link between the development of insulin resistance and low bone turnover - which may be of key essence in the development of the fragile bone structure and increased fracture risk demonstrated in subjects with abdominal obesity and T2D.

The relationship between obesity and fractures

There has been very limited analysis of the relationship between obesity and fractures in the orthopaedic literature. It has been established for some years that underweight individuals are at greater risk of proximal femoral fractures but recently there has been interest in the susceptibility of obese post-menopausal females to fracture. We have undertaken an analysis of 4886 adult patients who presented with a fracture and had their BMI assessed. Analysis has confirmed the relationship between underweight individuals and proximal femoral fractures but there is also a negative association between obesity and clavicle fractures in males and females and with calcaneal fractures in females. There is a positive relationship between obesity and proximal humeral, finger phalangeal and ankle fractures in males and with humeral diaphyseal, carpal and ankle fractures in females. There was no relationship found between open or multiple fractures and obesity.

Independent relationships between bone mineral density, regional body fat and insulin sensitivity in white males

BACKGROUND

Adiposity and insulin sensitivity may affect bone mineral density (BMD), but the confounding effect of weight hinders discrimination of independent associations. We explored whether regional fat masses and insulin sensitivity are independently related to BMD.

MATERIALS AND METHODS

Relationships between total and regional body fat, insulin sensitivity and measures of BMD in 8 different regions were evaluated in a cross section of 590 generally healthy, white males, 274 of whom received measurement of insulin sensitivity (Si) using the intravenous glucose tolerance test. Measurements included total, android and gynoid fat and lean body mass and regional BMDs by dual-energy X-ray absorptiometry. Linear regression analyses were combined in a mediation analysis to explore associations with each regional BMD.

RESULTS

Weight correlated positively with total fat mass (R²  = 0.67, P < 0.001) and negatively with Si (R²  = 0.14, P < 0.001). Body composition measures were consistently positively related to BMD in all regions except lumbar and thoracic spine. Accounting for body weight rendered negative majority of associations between total and regional fat masses and BMDs. An independent association between android fat and spine BMD was particularly apparent. Si was positively associated with total and limb BMD (P < 0.01) specifically among exercisers. Accounting for Si diminished the associations of total fat (negative) and lean body mass (positive) with total and limb BMD.

CONCLUSION

Android fat is independently negatively associated with spine BMD. Among those taking exercise, increased insulin sensitivity is associated with higher limb BMD and may underlie positive associations between lean body mass and BMD.

The Relationship Between BMI and Stability of Intertrochanteric Fracture Following Low-Energy Falls. A Retrospective Cohort Study

INTRODUCTION

Intertrochanteric proximal femur fractures are common injuries in the elderly. Certain patterns are considered unstable and confer increased risks. Risk factors for these patterns are not well defined. We sought to determine whether increased body mass index (BMI) was associated with increased risk of sustaining an unstable pattern intertrochanteric (IT) fracture following low-energy trauma. Materials and methods: Retrospective case review of all patients presenting to a level-2 trauma center between October 2010 and August 2014 with Intertrochanteric fracture. Fracture pattern (stable or unstable) and BMI were analyzed using odds ratios and age was controlled for.

RESULTS

Four hundred fifty-two patients were identified. No difference was found between fracture stability when BMI of 25 was used as a cutoff. However, when a BMI of 30 was used as a cutoff, there was a trend of difference (relative difference 30%) in rates of fracture type favoring unstable patterns in the obese group. This difference approached but did not reach statistical significance (P = .08). When adjusted for age, the difference remained but still did not reach statistical significance (P = .11).

DISCUSSION

Unstable type IT fractures were found more frequently in the obese cohort (BMI >30) than those who were not obese.

Understanding and managing secondary osteoporosis

INTRODUCTION

The term secondary osteoporosis (SO) identifies a reduction of bone mass related to a well-established disease or pharmacological agent. The identification of the underlying disease often represents a challenging situation in clinical practice.

AREAS COVERED

The prevalence of SO in the real world may vary, ranging from 17% to 80%; therefore, search for a form of SO represents a pillar when evaluating patients with osteoporosis. Guidelines for treatment of specific secondary forms of osteoporosis, such as glucocorticoid-induced osteoporosis, have been published even though often neglected in clinical practice. For the majority of SO, there are currently no specific guidelines concerning treatment with only few trials showing the effect of bone-active drugs on fracture risk reduction.

EXPERT OPINION

Healthcare professionals should be aware of the secondary forms of osteoporosis, in particular when the reason for reduced skeletal resistance is uncertain or when bone mineral density results are unsatisfactory in a patient compliant to therapy. In a few cases (such as, for example: no response to therapy, better classification of bone involvement in patients with kidney failure, suspicion of rare metabolic bone disease) bone biopsy is needed to investigate the patient. This review highlights recent advances in understanding and managing SO.

Obesity and bone metabolism

The interaction between obesity and bone metabolism is complex. The effects of fat on the skeleton are mediated by both mechanical and biochemical factors. Though obesity is characterized by higher bone mineral density, studies conducted on bone microarchitecture have produced conflicting results. The majority of studies indicate that obesity has a positive effect on skeletal strength, even though most likely the effects are site-dependent and, in fact, obese individuals might be at risk of certain types of fractures. Mechanical loading and higher lean mass are associated with improved outcomes, whereas systemic inflammation, observed especially with abdominal obesity, may exert negative effects. Weight loss interventions likely lead to bone loss over time. Pharmacological treatment options seem to be safe in terms of skeletal health; however, the skeletal effects of bariatric surgery are dependent on the type of surgical procedure. Malabsorptive procedures are associated with higher short-term adverse effects on bone health. In this narrative review, we discuss the effects of obesity and weight loss interventions on skeletal health.

BMI and Central Obesity With Falls Among Community-Dwelling Older Adults

INTRODUCTION

This study examined the associations of BMI category and central obesity status, with falls among community-dwelling older adults in the U.S.

METHODS

Data were drawn from the 2012 and 2014 U.S. Health and Retirement Study, a nationally representative longitudinal panel study funded by the National Institute of Aging. The study participants were U.S. community-dwelling older adults aged ≥65 years (N=3,383). Multiple logistic regression and Poisson regression analyses examined the associations of BMI category and central obesity (waist circumference >102 cm in men and >88 cm in women) with experiencing a fall and fall injury, after adjusting for all other covariates. A prospective analysis was conducted in which independent variables from 2012 were examined in relation to dependent variables measured in the same participants in 2014.

RESULTS

Overall, 35.2% of older adults experienced at least one fall in the past 2 years. Compared with those who were not, centrally obese older adults were more likely to experience a fall (AOR=1.37, 95% CI=1.01, 1.85) and fall more frequently (incidence rate ratio=1.15, 95% CI=1.03, 1.29). Fallers in the obese BMI category were less likely than normal-weight fallers to experience a fall injury (AOR=0.56, 95% CI=0.35, 0.91).

CONCLUSIONS

These findings suggest that (1) central obesity be measured when assessing older adults' fall risk and (2) specific community prevention strategies for centrally obese older adults be developed to better prevent falls and fall-related injuries.