Development of Subject-Specific Proximal Femur Finite Element Models Of Older Adults with Obesity to Evaluate the Effects of Weight Loss on Bone Strength

Physical activity attenuates the excess mortality risk from prolonged sitting time among adults with osteoporosis or osteopenia

PURPOSE

Osteoporosis is a common generalized skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. This study aims to crystallize associations of physical activity (PA) and sedentary behaviour with the survival of adults with osteoporosis or osteopenia.

METHODS

A total of 3103 participants aged 50 years or older from the National Health and Nutrition Examination Survey (NHANES) were included in the study. All participants were diagnosed with osteopenia or osteoporosis. Multivariable Cox proportional hazards regression models were used to assess the association of PA and sedentary behaviour with overall mortality, cancer-related mortality, and cardiovascular disease (CVD)-related mortality.

RESULTS

During 21349 person-years of follow-up, 675 deaths were documented. Highly active participants had a lower risk of all-cause (hazard ratios [HR] = 0.61; 95% confidence interval [CI], 0.42-0.87; P for trend = 0.004), cancer-specific (HR = 0.64; 95%CI, 0.35-1.17; P for trend = 0.132), CVD-specific (HR = 0.75; 95%CI, 0.45-1.25; P for trend = 0.452), and other (HR, 0.51; 95%CI, 0.29-0.88; P for trend = 0.005) mortality than inactive participants. And sitting time was not associated with mortality among physically active participants; while among those who were insufficiently active or inactive, longer sitting time was associated with increased risks of all-cause (HR per 1-h increase = 1.05; 95% CI, 1.01-1.09), cancer-specific (HR per 1 h increase = 0.98; 95% CI, 0.90-1.07), CVD-specific (HR per 1-h increase = 1.11; 95% CI = 1.04-1.18), and other (HR per 1-h increase = 1.05; 95% CI, 0.98-1.13) mortality in a dose-response manner.

CONCLUSIONS

PA can attenuate the excess mortality risk from prolonged sitting for individuals with osteoporosis and/or osteopenia. The combination of prolonged sedentary behaviour with inactive (participants without any PA during a week) PA was associated with an increased risk of mortality. The all-cause mortality risk of individuals who engage in less than 150 min/wk PA and sit more than 8 h/d is 2.02 (95% CI, 1.37-2.99) times higher than that of individuals who engage in more than 150 min/wk PA and sit less than 4 h/d.

Strategies to reduce the onset of sleeve gastrectomy associated bone loss (STRONG BONES): Trial design and methods

Background

Despite recognized improvements in obesity-related comorbidities, mounting evidence implicates surgical weight loss in the onset of skeletal fragility. Sleeve gastrectomy (SG) is the most commonly performed bariatric procedure and is associated with 3-7% axial bone loss in the year following surgery. Bisphosphonates are FDA-approved medications for the prevention and treatment of age-related bone loss and may represent a strategy to reduce bone loss following SG surgery.

Methods

The Strategies to Reduce the Onset of Sleeve Gastrectomy Associated Bone Loss (STRONG BONES) trial (NCT04922333) is designed to definitively test whether monthly administration of the bisphosphonate, risedronate, for six months can effectively counter SG-associated bone loss. Approximately 120 middle-aged and older (≥40 years) SG patients will be randomized to six months of risedronate or placebo treatment, with skeletal outcomes assessed at baseline, six, and 12-months post-surgery. The primary outcome of the trial is 12-month change in total hip areal bone mineral density (aBMD), measured by dual energy x-ray absorptiometry (DXA). This will be complemented by DXA-acquired aBMD assessment at other skeletal sites and quantitative computed tomography (QCT) derived changes in bone quality. Change in muscle mass and function will also be assessed, as well as biomarkers of bone health, turnover, and crosstalk, providing mechanistic insight into intervention-related changes to the bone-muscle unit.

Discussion

Results from the STRONG BONES trial have the potential to influence current clinical practice by determining the ability of bisphosphonate use to mitigate bone loss and concomitant fracture risk in middle-aged and older SG patients.

Acetabular Implant Finite Element Simulation with Customised Estimate of Bone Properties

The goal of the study is to analyse the strength and stability of a system comprising the pelvis and a customised implant under functional loads using the finite element method. We considered a technique for assessing the elastic properties of bone tissue via computer tomography, constructing finite element models of pelvic bones and a customised endoprosthesis based on the initial geometric models obtained from the National Medical Research Centre for Oncology n.a. N.N. Blokhin (Moscow, Russia). A series of calculations were carried out for the stress-strain state of the biomechanical system during walking, as well as at maximum loads when ascending and descending stairs. The analysis provided conclusions about the strength and stability of the studied device.

Study on the impact of the therapeutic swimming on elderly women diagnosed with osteoporosis

Introduction The adult woman has a complex of endocrine metabolic changes that can influence and cause various disorders in the body regarding the decrease of functional and regulatory ca-pacities. The involuntary changes in a woman's aging highlight both the appearance and the functionality. In this sense, we intend to conduct a study on morphological changes, parameters that represent risk factors in the development of osteoporosis. Studies by Kanis (1) and Munshi (2) show that maintaining adequate bone mass as well as ensuring adequate muscle tone can prevent osteoporosis, and a pronounced incidence of the onset and development of chronic de-generative pathologies can promote fractures. Material and method. In connection with the elu-cidation of this aspect, we will use the Frax estimation method, which is based on the introduc-tion of values obtained from medical evaluations. Regarding the study, we propose to the sub-jects a therapeutic swimming program to avoid the occurrence of osteoporotic fractures. Results and discussions. Regarding the field of factors favoring the estimation of a fracture in the items regarding cortisone treatments, alcohol consumption, digestive problems, minor traumas, the investigated subjects answered with No 100%.In order to obtain objective results, the study will continue for a period of 1 year, the intermediate tests will be performed after 4 months from the beginning of the work program and at the same time the program will undergo changes, de-pending on the results obtained from the evaluations. Conclusions. The implementation of this water exercise program will lead to adaptive changes in the direction of limiting the unevolu-tionary processes of senescence. Keywords: elderly women; osteoporosis; estimate; physical activity, therapeutic swimming

Caloric Intake in Renal Patients: Repercussions on Mineral Metabolism

The aim of this paper is to review current knowledge about how calorie intake influences mineral metabolism focussing on four aspects of major interest for the renal patient: (a) phosphate (P) handling, (b) fibroblast growth factor 23 (FGF23) and calcitriol synthesis and secretion, (c) metabolic bone disease, and (d) vascular calcification (VC). Caloric intake has been shown to modulate P balance in experimental models: high caloric intake promotes P retention, while caloric restriction decreases plasma P concentrations. Synthesis and secretion of the phosphaturic hormone FGF23 is directly influenced by energy intake; a direct correlation between caloric intake and FGF23 plasma concentrations has been shown in animals and humans. Moreover, in vitro, energy availability has been demonstrated to regulate FGF23 synthesis through mechanisms in which the molecular target of rapamycin (mTOR) signalling pathway is involved. Plasma calcitriol concentrations are inversely proportional to caloric intake due to modulation by FGF23 of the enzymes implicated in vitamin D metabolism. The effect of caloric intake on bone is controversial. High caloric intake has been reported to increase bone mass, but the associated changes in adipokines and cytokines may as well be deleterious for bone. Low caloric intake tends to reduce bone mass but also may provide indirect (through modulation of inflammation and insulin regulation) beneficial effects on bone. Finally, while VC has been shown to be exacerbated by diets with high caloric content, the opposite has not been demonstrated with low calorie intake. In conclusion, although prospective studies in humans are needed, when planning caloric intake for a renal patient, it is important to take into consideration the associated changes in mineral metabolism.

The effects of calorie restriction, intermittent fasting and vegetarian diets on bone health

Uncountable health care organizations, clinicians, and individuals are striving to prevent obesity and the many chronic medical conditions linked to it by advocating a healthy lifestyle that includes measures such as reducing dietary calorie intake (i.e., calorie restriction = CR and intermittent fasting = IF) or limiting/abolishing animal source foods (i.e., practices termed vegetarianism and veganism). Although these regimens are traditionally considered healthy, their real impact on bone health has yet to be established, and some studies have reported that they have negative effects on bone outcomes. The current work provides an overview of the studies carried out to examine the effect/s of CR, IF and vegetarian/vegan diets on bone health, and, in particular, on bone mineral density (BMD) and fracture risk. Although data on this subject are limited to small studies and there is no information specifically referring to fractures, CR, but not IF, seems to reduce BMD but does not seem to affect bone quality. Vegetarian diets (particularly vegan ones) are associated with significantly lower BMD values with respect to omnivorous ones and could, potentially, increase the risk of fractures. Given these considerations, individuals who decide to follow these diets should be aware of the risk of osteoporosis and of bone fractures and should introduce dietary sources of calcium and Vitamin D and/or supplementation. Future studies examining fracture/osteoporosis incidence in selected populations will be able expand our knowledge about the safety of these diets and the risks linked to them.

Prediction of lumbar vertebral body compressive strength of overweight and obese older adults using morphed subject-specific finite-element models to evaluate the effects of weight loss

BACKGROUND

Diet and exercise can promote weight loss in older adults; however, there is potential to increase fracture risk due to loss of bone mineral density (BMD) known to accompany weight loss. Weight loss effects on measures of bone quality and strength are currently unknown.

AIMS

The purpose of this study is to develop subject-specific finite-element (FE) models of the lumbar spine and study the effect of intentional weight loss on bone strength in a pilot data set.

METHODS

Computed tomography (CT) scans of the lumbar spine of 30 overweight and obese (mean BMI = 29.7 ± 3.9 kg/m²), older adults (mean age = 65.9 ± 4.6 years) undergoing an 18-month intentional weight loss intervention were obtained at baseline and post-intervention. Measures of volumetric BMD (vBMD) and variable cortical thickness were derived from each subject CT scan. Development of the subject-specific FE models of the lumbar spine involved model morphing techniques to accelerate the development of the models. vBMD-derived material properties and cortical thickness measures were directly mapped to baseline and post-intervention models. Bone strength was estimated through simulation of a quasi-static uniaxial compression test.

RESULTS

From baseline to 18-month post-weight loss intervention, there were statistically significant decreases in estimated bone strength (6.5% decrease; p < 0.05). Adjusting for baseline bone measures and gender revealed no statistically significant correlations between weight change and change in vBMD, cortical thickness, or bone strength.

CONCLUSION

Integration of CT-based measures and FE models with conventional areal BMD can improve the understanding of the effects of intentional weight loss on bone health.

Effect of Exercise Modality During Weight Loss on Bone Health in Older Adults With Obesity and Cardiovascular Disease or Metabolic Syndrome: A Randomized Controlled Trial

The objective of this study was to determine the ability of either aerobic or resistance training to counter weight-loss-associated bone loss in older adults. There were 187 older adults (67 years, 70% women, 64% white) with obesity (BMI = 34.5 ± 3.7 kg/m² ) and cardiovascular disease and/or metabolic syndrome who were randomized to participate in an 18-month, community-based trial, with a follow-up assessment at 30 months. Intervention arms included: weight loss alone (WL; 7% to 10% baseline weight), WL plus aerobic training (WL + AT), and WL plus resistance training (WL + RT), as well as DXA-acquired total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD), and trabecular bone score (TBS). Biomarkers of bone turnover (procollagen type 1 N-terminal propeptide, C-terminal telopeptide of type 1 collagen) were measured at baseline, 6, 18, and 30 (aBMD and TBS only) months. CT-acquired hip and spine volumetric BMD (vBMD), cortical thickness, and bone strength were measured in a subset at baseline (n = 55) and 18 months. Total hip aBMD was reduced by 2% in all groups at 18 months, with a primary analysis showing no significant treatment effects for any DXA, biomarker, or CT outcome. After adjustment for WL and follow-up at 30 months, secondary analyses revealed that total hip [-0.018 (-0.023 to -0.012) g/cm² versus -0.025 (-0.031 to -0.019) g/cm² ; p = 0.05] and femoral neck [-0.01 (-0.009 to 0.008) g/cm² versus -0.011 (-0.020 to -0.002) g/cm² ; p = 0.06] aBMD estimates were modestly attenuated in the WL + RT group compared with the WL group. Additionally, lumbar spine aBMD was increased in the WL [0.015 (0.007 to 0.024) g/cm² ] and the WL + RT [0.009 (0.000 to 0.017) g/cm² ] groups compared with the WL + AT [-0.003 (-0.012 to 0.005)g/cm² ] group; both p ≤ 0.01. Community-based exercise does not prevent bone loss during active WL in older adults; however, adding RT may help minimize long-term hip bone loss. © 2018 American Society for Bone and Mineral Research.

Opportunistic Screening for Osteoporosis Using Computed Tomography: State of the Art and Argument for Paradigm Shift

PURPOSE OF REVIEW

Osteoporosis is disproportionately common in rheumatology patients. For the past three decades, the diagnosis of osteoporosis has benefited from well-established practice guidelines that emphasized the use of dual x-ray absorptiometry (DXA). Despite these guidelines and the wide availability of DXA, approximately two thirds of eligible patients do not undergo testing. One strategy to improve osteoporosis testing is to employ computed tomography (CT) examinations obtained as part of routine patient care to "opportunistically" screen for osteoporosis, without additional cost or radiation exposure to patients. This review examines the role of opportunistic CT in the evaluation of osteoporosis.

RECENT FINDINGS

Recent evidence suggests that opportunistic measurement of bone attenuation (radiodensity) using CT has sensitivity comparable to DXA. More importantly, such an approach has been shown to predict osteoporotic fractures. The paradigm shift of using CTs obtained for other reasons to opportunistically screen for osteoporosis promises to substantially improve patient care.