Bone Mass Distribution Research Articles

Sacral Bone Mass Distribution Assessed by Averaged Three-Dimensional CT Models: Implications for Pathogenesis and Treatment of Fragility Fractures of the Sacrum.

Fragility fractures of the sacrum are increasing in prevalence due to osteoporosis and epidemiological changes and are challenging in their treatment. They exhibit specific fracture patterns with unilateral or bilateral fractures lateral to the sacral foramina, and sometimes an additional transverse fracture leads to spinopelvic dissociation. The goal of this study was to assess sacral bone mass distribution and corresponding changes with decreased general bone mass. Clinical computed tomography (CT) scans of intact pelves in ninety-one individuals (mean age and standard deviation, 61.5 ± 11.3 years) were used to generate three-dimensional (3D) models of the sacrum averaging bone mass in Hounsfield units (HU). Individuals with decreased general bone mass were identified by measuring bone mass in L5 (group 1 with <100 HU; in contrast to group 2 with ≥100 HU). In group 1, a large zone of negative Hounsfield units was located in the paraforaminal lateral region from S1 to S3. Along the trans-sacral corridors, a Hounsfield unit peak was observed laterally, corresponding to cortical bone of the auricular surface. The lowest Hounsfield unit values were found in the paraforaminal lateral region in the sacral ala. An intermediate level of bone mass was observed in the area of the vertebral bodies, which also demonstrated the largest difference between groups 1 and 2. Overall, the Hounsfield units were lower at S2 than S1. The models of averaged bone mass in the sacrum revealed a distinct 3D distribution pattern. The negative values in the paraforaminal lateral region may explain the specific fracture patterns in fragility fractures of the sacrum involving the lateral areas of the sacrum. Transverse fractures located between S1 and S2 leading to spinopelvic dissociation may occur because of decreased bone mass in S2. The largest difference between the studied groups was found in the vertebral bodies and might support the use of transsacral or cement-augmented implants.

Effects of Habitual Physical Activity and Fitness on Tibial Cortical Bone Mass, Structure and Mass Distribution in Pre-pubertal Boys and Girls: The Look Study.

Targeted weight-bearing activities during the pre-pubertal years can improve cortical bone mass, structure and distribution, but less is known about the influence of habitual physical activity (PA) and fitness. This study examined the effects of contrasting habitual PA and fitness levels on cortical bone density, geometry and mass distribution in pre-pubertal children. Boys (n=241) and girls (n=245) aged 7-9years had a pQCT scan to measure tibial mid-shaft total, cortical and medullary area, cortical thickness, density, polar strength strain index (SSIpolar) and the mass/density distribution through the bone cortex (radial distribution divided into endo-, mid- and pericortical regions) and around the centre of mass (polar distribution). Four contrasting PA and fitness groups (inactive-unfit, inactive-fit, active-unfit, active-fit) were generated based on daily step counts (pedometer, 7-days) and fitness levels (20-m shuttle test and vertical jump) for boys and girls separately. Active-fit boys had 7.3-7.7% greater cortical area and thickness compared to inactive-unfit boys (P<0.05), which was largely due to a 6.4-7.8% (P<0.05) greater cortical mass in the posterior-lateral, medial and posterior-medial 66% tibial regions. Cortical area was not significantly different across PA-fitness categories in girls, but active-fit girls had 6.1% (P<0.05) greater SSIpolar compared to inactive-fit girls, which was likely due to their 6.7% (P<0.05) greater total bone area. There was also a small region-specific cortical mass benefit in the posterior-medial 66% tibia cortex in active-fit girls. Higher levels of habitual PA-fitness were associated with small regional-specific gains in 66% tibial cortical bone mass in pre-pubertal children, particularly boys.

Finite Element Analysis of Denosumab Treatment Effects on Vertebral Strength in Ovariectomized Cynomolgus Monkeys.

Finite element analysis has not yet been validated for measuring changes in whole-bone strength at the hip or spine in people after treatment with an osteoporosis agent. Toward that end, we assessed the ability of a clinically approved implementation of finite element analysis to correctly quantify treatment effects on vertebral strength, comparing against direct mechanical testing, in cynomolgus monkeys randomly assigned to one of three 16-month-long treatments: sham surgery with vehicle (Sham-Vehicle), ovariectomy with vehicle (OVX-Vehicle), or ovariectomy with denosumab (OVX-DMAb). After treatment, T12 vertebrae were retrieved, scanned with micro-CT, and mechanically tested to measure compressive strength. Blinded to the strength data and treatment codes, the micro-CT images were coarsened and homogenized to create continuum-type finite element models, without explicit porosity. With clinical translation in mind, these models were then analyzed for strength using the U.S. Food and Drug Administration (FDA)-cleared VirtuOst software application (O.N. Diagnostics, Berkeley, CA, USA), developed for analysis of human bones. We found that vertebral strength by finite element analysis was highly correlated (R(2) = 0.97; n = 52) with mechanical testing, independent of treatment (p = 0.12). Further, the size of the treatment effect on strength (ratio of mean OVX-DMAb to mean OVX-Vehicle, as a percentage) was large and did not differ (p = 0.79) between mechanical testing (+57%; 95% CI [26%, 95%]) and finite element analysis (+51% [20%, 88%]). The micro-CT analysis revealed increases in cortical thickness (+45% [19%, 73%]) and trabecular bone volume fraction (+24% [8%, 42%]). These results show that a preestablished clinical finite element analysis implementation-developed for human bone and clinically validated in fracture-outcome studies-correctly quantified the observed treatment effects of denosumab on vertebral strength in cynomolgus monkeys. One implication is that the treatment effects in this study are well explained by the features contained within these finite element models, namely, the bone geometry and mass and the spatial distribution of bone mass. © 2016 American Society for Bone and Mineral Research.

Proximal femur geometry assessed by hip structural analysis in hip fracture in women.

In the pathogenesis of hip fracture, proximal femur geometry plays a key role as well as decreased bone density. The hip structural analysis (HSA) processes dual energy X-ray absorptiometry (DXA) images containing information on the geometry closely related to the strength of the proximal femur. The objective of this study was to investigate bone mineral density (BMD) and mechanical properties of the proximal femur in a group of women with a previous contralateral hip fragility fracture compared to women without history of hip fracture. In a population of postmenopausal women, we evaluated bone density by DXA and bone geometry using the HSA parameters (femoral strength index, cross-sectional moment of inertia, cross-sectional area, section modulus, and buckling ratio) including hip axis length (HAL) and neck shaft angle. Of a total of 62 postmenopausal women, twenty-six with a history of hip fracture had a mean femoral neck BMD significantly lower in comparison with 36 women in the control group (0.703 versus 0.768 g/cm(2), p = 0.0347). There was a statistically significant difference between groups also for HAL (106.75 mm in fracture group versus 100.93 mm in control group, p = 0.0015). Our results demonstrated that all the geometrical parameters resulted worst into the group of patients with history of hip fracture, even though only the HAL was significantly lower in control subjects. In our opinion HSA is useful to characterize the risk of hip fracture in postmenopausal women, providing additional data on the spatial distribution of bone mass strongly related to bone strength.

The distribution of bone mass in the lumbar vertebrae: are we measuring the right target?

Background contextThe ideal target of bone mineral density (BMD) measurements of the spine is the trabecula-rich vertebral body. Yet, spine BMD measurements routinely obtained with dual-energy X-ray absorptiometry also include the posterior elements of the vertebra, which are mainly cortical bone and insensitive to bone loss. PurposeWe compared the bone mass of the vertebral body and posterior elements to determine the contributions of vertebral components to vertebral BMD measurements. Study designA micro-computed tomography study of lumbar vertebral bone. MethodsFrom a spine archive, 144 cadaveric lumbar vertebrae (L1–L5) from 48 male human spines (mean age, 50 years) were scanned in air using micro-computed tomography to measure bone volume, bone mineral content (BMC) and BMD of the vertebral body, posterior elements, and entire vertebra. The contributions of the vertebral components to the total vertebral BMC and volume were compared, and the correlations between the BMC and BMD of the vertebrae and their components were examined. ResultsOverall, the vertebral body contributed about one-third of the total vertebral BMC and two-thirds of the total vertebral volume, and the posterior elements contributed the remainder. The vertebral body BMC and BMD were poorly correlated to those of the posterior elements (r=0.39 for BMC and r=0.34 for BMD, p<.0001) and moderately correlated to the whole vertebra (r=0.77 and 0.75, respectively, p<.0001). The BMC and BMD of the posterior elements and whole vertebra were more strongly correlated (r=0.89 and 0.84, respectively, p<.0001). ConclusionsThe posterior elements are the primary contributor to vertebral BMC and BMD measurements. Dual-energy X-ray absorptiometry spine BMD measurements are likely to be more representative of the posterior elements than the targeted vertebral body. The findings elucidate the extent of the limitation of dual-energy X-ray absorptiometry spine BMD measurements.

An approach for determining quantitative measures for bone volume and bone mass in the pediatric spina bifida population

BackgroundThe pediatric spina bifida population suffers from decreased mobility and recurrent fractures. This study aimed to develop a method for quantifying bone mass along the entire tibia in youth with spina bifida. This will provide information about all potential sites of bone deficiencies. MethodsComputed tomography images of the tibia for 257 children (n=80 ambulatory spina bifida, n=10 non-ambulatory spina bifida, n=167 typically developing) were analyzed. Bone area was calculated at regular intervals along the entire tibia length and then weighted by calibrated pixel intensity for density weighted bone area. Integrals of density weighted bone area were used to quantify bone mass in the proximal and distal epiphyses and diaphysis. Group differences were evaluated using analysis of variance. FindingsNon-ambulatory children suffer from decreased bone mass in the diaphysis and proximal and distal epiphyses compared to ambulatory and control children (P≤0.001). Ambulatory children with spina bifida showed statistically insignificant differences in bone mass in comparison to typically developing children at these sites (P>0.5). InterpretationThis method provides insight into tibial bone mass distribution in the pediatric spina bifida population by incorporating information along the whole length of the bone, thereby providing more information than dual-energy x-ray absorptiometry and peripheral quantitative computed tomography. This method can be applied to any population to assess bone mass distribution across the length of any long bone.

Diabetes, diabetic complications, and fracture risk.

Diabetes and osteoporosis are both common diseases with increasing prevalences in the aging population. There is increasing evidence corroborating an association between diabetes mellitus and bone. This review will discuss the disease complications of diabetes on the skeleton, highlighting findings from epidemiological, molecular, and imaging studies in animal models and humans. Compared to control subjects, decreased bone mineral density (BMD) has been observed in type 1 diabetes mellitus, while on average, higher BMD has been found in type 2 diabetes; nonetheless, patients with both types of diabetes are seemingly at increased risk of fractures. Conventional diagnostics such as DXA measurements and the current fracture risk assessment tool (FRAX) risk prediction algorithm for estimating risk of osteoporotic fractures are not sufficient in the case of diabetes. A deterioration in bone microarchitecture and an inefficient distribution of bone mass with insufficiency of repair and adaptation mechanisms appear to be factors of relevance. A highly complex and heterogeneous molecular pathophysiology underlies diabetes-related bone disease, involving hormonal, immune, and perhaps genetic pathways. The detrimental effects of chronically elevated glucose levels on bone should be added to the more well-known complications of diabetes.

LRP5 Regulates Human Body Fat Distribution by Modulating Adipose Progenitor Biology in a Dose- and Depot-Specific Fashion

SummaryCommon variants in WNT pathway genes have been associated with bone mass and fat distribution, the latter predicting diabetes and cardiovascular disease risk. Rare mutations in the WNT co-receptors LRP5 and LRP6 are similarly associated with bone and cardiometabolic disorders. We investigated the role of LRP5 in human adipose tissue. Subjects with gain-of-function LRP5 mutations and high bone mass had enhanced lower-body fat accumulation. Reciprocally, a low bone mineral density-associated common LRP5 allele correlated with increased abdominal adiposity. Ex vivo LRP5 expression was higher in abdominal versus gluteal adipocyte progenitors. Equivalent knockdown of LRP5 in both progenitor types dose-dependently impaired β-catenin signaling and led to distinct biological outcomes: diminished gluteal and enhanced abdominal adipogenesis. These data highlight how depot differences in WNT/β-catenin pathway activity modulate human fat distribution via effects on adipocyte progenitor biology. They also identify LRP5 as a potential pharmacologic target for the treatment of cardiometabolic disorders.

Human Proximal Femur Bone Adaptation to Variations in Hip Geometry

The study of bone mass distribution at proximal femur may contribute to understand the role of hip geometry on hip fracture risk. We examined how bone mineral density (BMD) of proximal femur adapts to inter individual variations in the femoral neck length (FNL), femoral neck width (FNW) and neck shaft angle (NSA). A parameterized and dimensionally scalable 3-D finite element model of a reference proximal femur geometry was incrementally adjusted to adopt physiological ranges at FNL (3.90-6.90cm), FNW (2.90-3.46cm), and NSA (109-141º), yielding a set of femora with different geometries. The bone mass distribution for each femur was obtained with a suitable bone remodelling model. The BMDs at the integral femoral neck (FN) and at the intertrochanteric (ITR) region, as well as the BMD ratio of inferomedial to superolateral (IM:SL) regions of FN and BMD ratio of FN:ITR were used to represent bone mass distribution. Results revealed that longer FNLs present greater BMD (g/cm3) at the FN, mainly at the SL region, and at the ITR region. Wider FNs were associated with reduced BMD at the FN, particularly at the SL region, and at the ITR region. Larger NSAs up to 129° were associated with BMD diminutions at the FN and ITR regions and with increases of the IM:SL BMD ratio while NSAs larger than 129° resulted in decrease of the IM:SL BMD ratio. These findings suggest hip geometry as moderator of the mechanical loading influence on bone mass distribution at proximal femur with higher FNL favoring the BMD of FN and ITR regions and greater FNW and NSA having the opposite effect. Augmented values of FNL and FNW seem also to favor more the BMD at the superolateral than at the inferomedial FN region.

3D statistical modeling techniques to investigate the anatomy of the sacrum, its bone mass distribution, and the trans-sacral corridors.

The complex anatomy of the sacrum makes surgical fracture fixation challenging. We developed statistical models to investigate sacral anatomy with special regard to trans-sacral implant fixation. We used computed tomographies of 20 intact adult pelves to establish 3D statistical models: a surface model of the sacrum and the trans-sacral corridor S1, including principal component analysis (PCA), and an averaged gray value model of the sacrum given in Hounsfield Units. PCA demonstrated large variability in sacral anatomy markedly affecting the diameters of the trans-sacral corridors. The configuration of the sacral alae and the vertical position of the auricular surfaces were important determinants of the trans-sacral corridor dimension on level S1. The statistical model of trans-sacral corridor S1 including the adjacent parts of the iliac bones showed main variation in length; however, the diameter was the main criterion for the surgically available corridor. The averaged gray value model revealed a distinct pattern of bone mass distribution with lower density particularly in the sacral alae. These advanced 3D statistical models provide a thorough anatomical understanding demonstrating the impact of sacral anatomy on positioning trans-sacral implants.

Birth is but our death begun: a bioarchaeological assessment of skeletal emaciation in immature human skeletons in the context of environmental, social, and subsistence transition.

The second millennium BC was a period of significant social and environmental changes in prehistoric India. After the disintegration of the Indus civilization, in a phase known as the Early Jorwe (1400-1000 BC), hundreds of agrarian villages flourished in the Deccan region of west-central India. Environmental degradation, combined with unsustainable agricultural practices, contributed to the abandonment of many communities around 1000 BC. Inamgaon was one of a handful of villages to persist into the Late Jorwe phase (1000-700 BC), wherein reliance on dry-plough agricultural production declined. Previous research demonstrated a significant decline in body size (stature and body mass index) through time, which is often used to infer increased levels of biocultural stress in bioarchaeology. This article assesses evidence for growth disruption in the immature human skeletal remains from Inamgaon by correlating measures of whole bone morphology with midshaft femur compact bone geometry and histology. Growth derangement is observable in immature archaeological femora as an alteration in the expected amount and distribution of bone mass and porosity in the midshaft cross-section. Cross-section shape matched expectations for older infants with the acquisition of bipedal locomotion. These results support the hypothesis that small body size was related to disruptions in homeostasis and high levels of biocultural stress in the Late Jorwe at Inamgaon. Further, the combined use of geometric properties and histological details provides a method for teasing apart the complex interactions among activity and "health," demonstrating how biocultural stressors affect the acquisition and quality of bone mass.

Influence of physical activity and skeleton geometry on bone mass at the proximal femur in 10- to 12-year-old children--a longitudinal study.

Physical activity (PA) have long been identified as a determining factor of the mineralization of the skeleton, particularly in children. Our research supports the hypothesis that the geometry of the pelvis and proximal femur (PF) might moderate the effect of PA in the relative mineralization of the PF subregions. Using a longitudinal observational study with two evaluations and a 1-year follow-up interval, we investigated the influence of PA and skeletal geometry in bone mineral density (BMD) and bone mass distribution at the PF in 96 girls and 81 boys (10-12 years). It is plausible that the geometry of the pelvis-PF structure moderates mechanical forces exerted at the hip and therefore creates different degrees of mineralization among PF subregions. Whole body and left hip dual X-ray absorptiometry scans were used to derive geometric measures of the pelvis-inter-acetabular distance (IAD) and PFabductor lever arm (ALA). BMD was measured at the integral, superolateral (SL), and inferomedial (IM) femoral neck (FN), and at the trochanter (TR). These subregions were used to represent bone mass distribution via three BMD ratios: FN/PF, IM/SL, and TR/PF. PA was measured using accelerometry and a bone-specific PA questionnaire (BPAQ). A longitudinal data approach revealed BPAQ as a positive predictor for all BMD variables (p < 0.05) except TR BMD in girls and FN BMD in boys. Comparing the most active with the less-active participants, the greatest benefits of PA were observed at the FN of the girls with the lowest IAD (p < 0.001), at the FN of the boys with the highest IAD (p < 0.001) and at the TR of the boys with the lowest ALA (p < 0.01). Geometric measures of IAD and ALA seem to moderate the effect of PA role in the relative mineralization of the PF regions. On the other hand, absolute BMD levels appear to be determined by mechanical loading.

D-35 Free Communication/Poster - The Aging Cardiovascular System and Exercise

Bone mass at the proximal femur (PF) may be influenced by both physical activity (PA) and bone geometry. Since bone geometry also appears to be determined by PA it is reasonable to analyze the relationship between these variables and determine the contribution of PA and geometry in bone mass. PURPOSE:To examine associations of PA with geometric characteristics of the pelvis-PF structure and with bone mineral density (BMD) of fracture-critical bone regions of PF. METHODS:Participants were 85 young adults, 50 females (age: 23.7±3.4 yrs) and 35 males (age: 24.4 ± 3.4 yrs). BMD was measured at the integral, superolateral (SL), and inferomedial (IM) femoral neck (FN), and at the trochanter (TR). These regions were used to represent bone mass distribution via three BMD ratios - FN:PF, IM:SL, and TR:PF. PA was evaluated with accelerometers and with a bone-specific PA questionnaire (BPAQ). Upper inter acetabular distance (UIAD), femoral neck axis length (FNAL), narrow neck width (NNW), abductor lever arm (ALA), and neck-shaft angle (NSA) were used as geometric measures and were derived from a whole body and PF DXA scans. All analyses were adjusted for age, body height, lean mass, calcium intake, and sex. RESULTS:Correlation analyses revealed that PA is positively associated with FNAL and NNW and negatively associated with UIAD while sedentary time is positively associated with UIAD (p<0.05). It were also observed positive associations (p<0.05) or a trend for positive associations (p=0.056 - 0.078) between PA and BMD at all bone regions. UIAD associated with TR BMD (r=-0.328, p=0.006) and ALA with FN:PF (r=-264,p=0.027). Stepwise regression models showed that PA (BPAQ or vigorous PA) explains up to 9% of the variance of the TR, integral, IM, and SL FN BMD (p<0.05) but with higher explanation at the TR than at FN regions. There was a negative association between UIAD and TR BMD (R2=4%, p=0.002), and between ALA and FN:PF (R2=9%, p=0.004). It was found a negative association between NSA and TR BMD (R2=6%, p=0.035) only in females. CONCLUSIONS:Despite being interrelated, PA and geometric characteristics of the pelvis-PF structure are independently associated to bone mass at PF regions. This work was funded by Portuguese Science and Technology Foundation (PTDC/DES/115607/2009) and PhD Scholarship (SFRH/BD/79828/2011).

Comparison of Buckling Ratio and Finite Element Analysis of Femoral Necks in Post-menopausal Women.

ObjectivesOsteoporosis is a prevalent problem amongst the elderly. Bone mineral density (BMD) obtained from dual X-ray absorptiometry (DXA) is the gold standard in diagnosing osteopenia (-1.0 < t < -2.5) and osteoporosis (t > -2.5). However, following osteoporosis therapy, increases in BMD may be unreliable. Although hip fracture risk can be reduced with the aid of drugs, treated patients still face considerable risk as most people who sustain hip fracture do not have generalized osteoporosis. A study of the local distribution of bone mass was necessary as they contribute to the geometry and consequently the bone strength.MethodsBy identifying the respective regions in the femoral neck, the geometric changes were localized and differed between each patient, proving that drug treatment elicits local changes in mean outer radius and mean cortical thickness. Numerical analysis also validated the above findings, where critical strain regions were predicted at similar zones and this is coherent with the fact that reduced thickness of the cortical bone has been related to increased risk of fracture initiation.ResultsHence, from individual radar plots, we can determine if the effect of drugs had outweighed the effect of aging. We can then propose a course of treatment drug better suited for the patient in the clinical scenario.ConclusionClinically, little conclusion can be drawn from just the BMD in osteopenic / osteoporotic patients. This emphasizes the necessity of using geometry and structure to predict fracture risk. Focusing on a patient specific analysis at a local level will improve diagnosis of osteoporosis and ultimately fracture prediction.

Osteoporosis and Osteoarthritis, Rheumatoid Arthritis and Spondylarthropathies

Osteoporosis (OP) commonly occurs in the setting of inflammatory arthritis, whereas there is an inverse relationship with osteoarthritis (OA). We review the recent updates in epidemiology and pathophysiology of OP relating to several arthridities. In ankylosing spondylitis, lateral lumbar spine dual x-ray absorptiometry is better at detecting osteoporosis compared with the AP view and patients receiving treatment with anti- tumor necrosis factor medications had lower levels of bone turnover markers. With regard to rheumatoid arthritis, anticitrullinated peptide positivity without clinical arthritis as well as higher levels of interleukin-6 is associated with decreased bone mineral density and polymorphisms in the vitamin D receptor in RA patients may predispose to OP. With regard to OA, results from the Global Longitudinal Study of Osteoporosis in Women study and several radiological studies suggest that differences in the distribution of bone mass at the femoral neck may account for the inverse relationship of OA and OP, and several studies suggest that OA and OP have opposing cytokine and bone metabolism marker profiles.

Femoral neck bone adaptation to weight-bearing physical activity by computational analysis

Individual differences in bone mass distribution at the proximal femur may be determined by daily weight-bearing physical activity (PA) since bone self-adapts according to the mechanical loads that is submitted. The aim of this study was to analyse computationally the effect of different weight-bearing PA types in the adaptation of the femoral neck (FN) by analysing regional differences in bone mineral density (BMD) at the integral FN and its superior, inferior, anterior and posterior subregions. To achieve this, it was adopted a 3-D femoral finite element (FE) model coupled with a suitable bone remodeling model. Different PA types were determined based both on ordinary lifestyle and mechanically more demanding PA as low magnitude impacts (L–I), moderate-magnitude impacts from odd directions (O–I) and high-magnitude vertical impacts (H–I). It was observed that as time spent in weight-bearing PA increases, BMD augment around the integral FN, but with different bone mass gain rates between subregions depending on the magnitude and directions of the hip contact forces; H–I was the type of weight-bearing PA which structurally most favor the gain of bone mass superiorly at the FN while both the H–I and the O–I types of PA promoted the largest bone mass gain rates at the anterior and posterior subregions of the FN. Because these types of weight-bearing PA were associated with a more uniform bone mass spatial distribution at the FN, they should provide a potential basis for targeted PA-based intervention programs for improving hip strength.

Regional distribution of bone mass in adult athletes and adult sedentary men

Summary Introduction The aim of this study was to explore the effects of weight-bearing physical activity practice on bone mass and regional distribution of bone mass in a group of young men. Summary of facts Fifteen young athletes (aged 23.3 ± 4.8 years) practising different kinds of sports (basketball, soccer, volleyball, and running) and 20 young sedentary men (aged 22.4 ± 5.5 years) participated in this study. Body weight and height were measured, and body mass index was calculated. Body composition (lean mass, fat mass and fat mass percentage) and bone mineral density (BMD) of the whole body (WB), the lumbar spine (L2–L4), the total hip (TH), the femoral neck (FN) and the total forearm (TF) were measured by dual-energy X-ray absorptiometry (DXA). The ratios head BMD/WB BMD, L2–L4 BMD/WB BMD, TH BMD/WB BMD and TF BMD/WB BMD were calculated. WB BMD, L2–L4 BMD, TH BMD, FN BMD and TH BMD/WB BMD were higher in athletes compared to the controls while TF BMD, head BMD/WB BMD, L2–L4 BMD/WB BMD and TF BMD/WB BMD were not significantly different between the two groups. Conclusion This study suggests that weight-bearing physical activity has a positive influence on BMD and can also influence bone mass distribution in young men.

Pelvis width associated with bone mass distribution at the proximal femur in children 10–11 years old

Differences in skeletal geometry may generate different patterns of mechanical loading to bone. Impact and muscle loading during physical activity have been shown to influence skeletal geometry. The purpose of this study was to compare geometric measures of the pelvis and proximal femur (PF) of young children and to analyze the contribution and potential interaction of these geometric measures with physical activity on PF bone mass distribution. Participants were 149 girls and 145 boys, aged 10-11years. Total body and left hip DXA scans were used to derive pelvic and PF geometric measures and PF bone mineral density (BMD) at the femoral neck (FN), trochanter (TR), and intertrochanter (IT). These subregions were used to represent bone mass distribution via three BMD ratios: FN:PF, TR:PF, and IT:PF. Physical activity was objectively measured using accelerometry, and maturity was estimated as the years of distance from peak height velocity. When compared to boys, girls had a wider pelvic diameter and greater interacetabular distances (p<0.001), lower BMD at FN, TR, and IT (p<0.05), and higher TR:PF (p<0.001). After controlling for maturity, body height, and lean body mass, the interacetabular distance in girls explained 21.1% (β=0.713, p<0.001) in TR:PF and 2.9% (β=-0.179, p=0.031) in the IT:PF. Neck-shaft angle explained 5.6% (β=-0.265, p=0.001) of the IT:PF and 3.1% (β=0.194, p=0.018) of the FN:PF. In boys, FN axis length explained 2.9% (β=0.195, p=0.040) of TR:PF. There was no main effect of physical activity or interaction effect with pelvic geometry in explaining BMD differences among the subregions of the PF. Even before sexual dimorphism, girls have a wider pelvis than boys, which accounted for proportionally greater BMD of the TR than other subregions of the PF.

Computational Anatomy in the Study of Bone Structure

Osteoporosis is a major public health threat for millions of Americans with billions of dollars per year of national direct costs for osteoporotic fractures. Osteoporosis results in a decrease in overall bone mass and subsequent increase in the risk of bone fracture. Bone strength arises from the combination of bone size and shape, the distribution of bone mass throughout the structure, and the quality of the bone material. Advances in medical imaging have enabled a comprehensive assessment of bone structure through the analysis of high-resolution scans of relevant anatomical sites, eg, the proximal femur. However, conventional imaging analysis techniques use predefined regions of interest that do not take full advantage of such scans. Recently, computational anatomy, a set of imaging-based analysis algorithms, has emerged as a promising technique in studies of osteoporosis. Computational anatomy enables analyses that are not biased to one particular region and provide a more complete assessment of the whole structure. In this article, we review studies that have used computational anatomy to investigate the structure of the proximal femur in relation to age, fracture, osteoporotic treatment, and spaceflight effects.

Sex-specific association of physical activity with bone mass distribution at the femoral neck and trochanter in young adults

Sex-specific association of physical activity with bone mass distribution at the femoral neck and trochanter in young adults