Dynamic Foot Pressure During Walking: A Potential Indicator of Bone Mineral Density.

BACKGROUND: Physical skeletal loading can affect the bone mineral density (BMD). This study investigated the association between BMD and dynamic foot pressure during gait. METHODS: A total of 104 patients (mean age, 62.6 ± 12.4 years; 23 male and 81 female) who underwent dual x-ray absorptiometry and pedobarography were included. BMD values of the lumbar spine, femoral neck, and total femur were assessed. The mean and maximum pressures were measured at the hallux, lesser toes, 1st metatarsal head, 2nd and 3rd metatarsal heads, 4th and 5th metatarsal heads, midfoot, medial heel, and lateral heel. Multivariable regression analysis was performed to identify factors significantly associated with BMD. RESULTS: The lumbar spine BMD was significantly associated with the mean pressure at the 4th and 5th metatarsal heads (p = 0.041, adjusted R 2 of model = 0.081). The femoral neck BMD was significantly associated with the maximum pressure at the 2nd and 3rd metatarsal heads (p = 0.002, adjusted R 2 = 0.213). The total femoral BMD also showed a significant association with the maximum pressure at the 2nd and 3rd metatarsal heads (p = 0.003, adjusted R 2 = 0.360). CONCLUSIONS: Foot plantar pressure during gait was significantly associated with BMD, and could potentially be used to predict the presence of osteoporosis. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Effect of gait types and external weight carrying strategies on the femoral neck strains during stair descent.

Gait and weight carrying method may change the femoral neck load during stair descent. Applying specific gait and weight carrying methods may reduce the femoral neck load during stair descent, which may reduce hip pain, hip pain related falls and fall related fractures for the older population. The purpose of this study was to test the effect of different gait types (step-over-step v.s. step-by-step) and external weight carrying strategies (ipsilateral v.s. contralateral side) on the femoral neck load, discover which method could reduce the femoral neck load effectively. Seventeen healthy adults from 50 to 70 yrs old were recruited. The kinematic and kinetic analysis, musculoskeletal modelling method were used to estimate the joint and muscle loads for the lower extremities. Finite element analysis was used with the femur model to calculate the femoral neck strains during stair descent with different gait types and weight carrying strategies. The compressive strains were reduced for step-by-step gait method than step-over-step (p<0.015, 12.3-17.4% decrease of strains), the tensile strains were significantly increased for the trailing leg of step-by-step than the leading leg (p<0.001, 24.7% increase of strains). Contralateral weight carrying increased compressive and tensile strains than ipsilateral (p<0.001, 9.9-24.5% increase of strains) in most conditions. Applying step-by-step method and avoiding contralateral side weight carrying could be effective to reduce femoral neck strains. These outcomes could be helpful for the older population to reduce the risks of hip pain, femoral neck pain or pain related falls and fractures.

Rapid trabecular bone growth in puberty associated with stiffer arteries in adulthood - longitudinal study on healthy young males.

Longitudinal bone content data from puberty to adulthood was assessed in 102 healthy males and associations with arterial health in adulthood was analysed. Bone growth in puberty was related to arterial stiffening and final bone mineral content to decreased arterial stiffness. Relationships with arterial stiffness were dependent on the studied bone regions. INTRODUCTION: Our aim was to assess the relationships between arterial parameters in adulthood and bone parameters in several locations longitudinally from puberty to 18-years and cross-sectionally at 18-years. METHODS: 102 healthy male data from a 7-year follow-up study was used to analyse total body (TB), femoral neck (FN) and lumbar spine (LS) mineral content and density by DXA, carotid intima-media thickness (cIMT) by ultrasound, carotid-femoral pulse wave velocity (cfPWV) and heart rate adjusted augmentation index (AIxHR75) by applanation tonometry. RESULTS: Linear regression analysis revealed negative associations between LS bone mineral density (BMD) and cfPWV [ß=-1.861, CI -3.589, -0.132, p=0.035] which remained significant [ß=-2.679, CI -4.837, -0.522, p=0.016] after adjustment to smoking, lean mass, weight category, pubertal stage, physical fitness, and activity. For AIxHR75 similar results were present [ß=-0.286, CI -0.553, -0.020, p=0.035], but were dependent on confounders. Analysis on pubertal bone growth speed showed independent positive associations to AIxHR75 between Δ FN bone mineral apparent density (BMAD) [ß=672.50, CI 348.07, 996.93, p<0.001] and Δ LS BMAD [ß=700.40, CI 57.384, 1343.423, p=0.033]. Further analysis combining pubertal bone growth and adulthood BMC revealed that the relationships of AIxHR75 with LS BMC and ΔFN BMAD were independent of each other. CONCLUSION: Trabecular bone regions like lumbar spine and femoral neck, showed stronger relationships with arterial stiffness. Rapid bone growth in puberty is related to arterial stiffening, while final bone mineral content relates to decreased arterial stiffness. These results could indicate that bone metabolism is independently associated with arterial stiffness rather than bone and arteries just having common traits of growth and maturation.

Contribution of Hip Abductors Muscles on Bone Mineral Density and Functionality in Older Women.

BACKGROUND: Despite the well-established role of muscle in maintaining bone mass and physical performance, there are still few studies that assess the relationship between muscle groups and specific bone sites and its contribution to physical function in older people. The aim of the study is to verify the association between hip and knee's muscle strength and bone mineral density of the femoral neck (BMD-FN) and investigated which muscle strength that are related with BMD-FN is associated with physical function in older women. METHODOLOGY: This is a cross-sectional study of 94 women over the age of 60 years, physically independent. Muscle strength of the hip and knee was evaluated using an isokinetic dynamometer (Biodex, USA) to obtain peak torque (PT). The BMD-FN was obtained using dual-energy x-ray absorption densitometry (DXA). Physical function was evaluated by the Timed Up and Go (TUG), gait speed (GS), five times stand to sit (5TSS) and single-leg stance (SS). To verify the association between muscle strength (independent variable) and the BMD-FN (dependent variable) and the relationship between muscle strength (independent variable) and clinical tests (dependent variable), the multiple linear regression was carried out, adjusted for age, time of menopause, height and level of physical activity. All of the analyses were carried out by the SPSS 17.0 software, with a level of p < 0.05 significance. RESULTS: We found an association between the hip abductors PT and the BMD-FN and between hip abductors PT and all clinical tests. CONCLUSION: We observe that hip abductor muscle strength contributes to BMD-FN and to performance in several clinical tests in older women. These findings reinforce the importance of this musculature not only for improving balance and gait, but also it can be a strategy to maintain/improve bone mass in the femoral neck in this population.

Skeletal site-specific effects of jump training on bone mineral density in adults: a systematic review and meta-analysis.

Preserving or preventing declines in bone mineral density (BMD) is imperative. As jumping is a high-impact bone-loading action, this meta-analysis evaluated the efficacy of jump training to improve BMD and bone turnover relative to non-jumping controls in men and women > 18 years, following Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines. PubMed and COCHRANE Library databases were searched until February 2022. Fifteen articles (19 jumping-trials) met the predetermined search criteria. Eighteen trials were included for BMD data (n = 666 participants). There was a significant small-moderate effect of jumping on femoral neck BMD (%mean difference: 95%CI, +1.50%: 0.83%; 2.17%, p < 0.0001), that remained significant after sub-analysis by age for both younger (+1.81%: 0.98%; 2.65%) and older adults (+1.03%: 0.02%; 2.03%). BMD of total hip (+1.26%: 0.56%; 1.96% vs + 0.06%: -0.96%; 1.08%), and trochanter (+0.84%: 0.20%; 1.48% vs -0.16%: -1.08%; 0.76%) increased significantly with jump training only in younger adults and non-significantly at the lumbar spine (+0.84%: -0.02%; 1.7% vs -0.09%: -0.96%; 0.77%) only in younger but not older adults, respectively. The BMD response to jump training appears to be site-specific, with the highest sensitivity at the femoral neck. No dose-response effect suggests moderate certainty of a gain in femoral neck BMD when performing the median jump-load of 50 jumps four times weekly.

The beneficial effects of square dance on musculoskeletal system in early postmenopausal Chinese women: a cross-sectional study.

BACKGROUND: This study was set to investigate the correlation between square dance and musculoskeletal system of early postmenopausal Chinese women. METHODS: Chinese postmenopausal women, who had been without menstruation for 1-10 years from the onset of menopause were recruited from community centers for this study. A standardized structured face-to-face interview was performed to collect demographic information, life styles, personal medical history, diet and menstrual status. Subjects who had been practicing regular square dance without participated in other sports activities for more than 2 years and over 4 h per week (usually more than 45 min per time and more than 5 times per week) were assigned to square dance group. Those postmenopausal women who had not participated in regular exercises (no more than 0.5 h per week) were recruited as the sedentary control group. Bone mineral density (BMD) of spine, total hip and femoral neck was measured by using dual-energy X-ray absorptiometry. Lower limb muscle strength was measured for the non-dominant leg, body flexibility was measured by a simple trunk bend-and-reach test, and body balance was evaluated using a single-stance test for the non-dominant leg. Independent two-tailed Student's t-test was used for data analysis. RESULTS: 152 subjects from community centers were selected for this study and divided into square dance group (n = 74) and control group (n = 78). The square dance subjects had higher lumbar spine BMD (p = 0.01) and total hip BMD (p = 0.02) than control subjects, but there was no significant difference of femoral neck BMD (p = 0.48) between these two groups. Functional testing indicated that square dance subjects had higher lower limb muscle strength (p < 0.01) and longer single-stance time (p = 0.02) than the control subjects, but there was no significant difference in trunk bend-and-reach (p = 0.12) between these two groups. CONCLUSION: Our results show that postmenopausal Chinese women can get beneficial effects, like higher BMD, stronger lower limb muscle and improved body balance ability on musculoskeletal system by participating in square dance regularly.

Mediterranean dietary pattern and bone mineral density: a systematic review and dose-response meta-analysis of observational studies.

BACKGROUND: We aimed to systematically review the literature and test the dose-response relationship between adherence to the Mediterranean diet (MedDiet) and values of bone mineral density (BMD) in adults. METHODS: Relevant observational studies were selected through searching PubMed, Scopus, and Web of Science databases up to March 4, 2021. A random-effects dose-response meta-analysis was performed to estimate the change in total and regional-specific BMD for a 2-point increment in the score of adherence to the MedDiet, and to clarify the shape of these associations. RESULTS: Seven cross-sectional and one cohort studies with a total number of 13,209 participants were included in the final analyses. Each 2-point increment in the score of adherence to the MedDiet was associated with 0.009 (95% CI: 0.002, 0.016; I2 = 34%, n = 7), 0.006 (95% CI: 0.001, 0.012; I2 = 34%, n = 7), 0.005 (95% CI: 0.003, 0.007; I2 = 1%, n = 4), 0.005 (95% CI: 0.002, 0.008; I2 = 0%, n = 3), and 0.007 (95% CI: 0.005, 0.009; I2 = 0%, n = 4) gr/cm2 higher BMD of lumbar spine, femoral neck, hip, trochanter, and whole body, respectively. There was a positive linear relationship between the MedDiet adherence score and BMD of hip and trochanter. A nonlinear relationship was seen for lumbar spine, femoral neck, and whole body, with sharper increase in the BMD at lower MedDiet scores. The associations remained significant after controlling for important confounders including body weight, physical activity, smoking status, and energy intake. CONCLUSION: Greater adherence to the MedDiet was associated with a small but important increase in BMD at the lumbar spine, femoral neck, hip, trochanter, and whole body. Adopting a Mediterranean-style eating pattern may have modest beneficial effects on bone health.

Characterization of pain-related behaviors, changes in bone microarchitecture and sensory innervation induced by chronic cadmium exposure in adult mice.

Because of the relative lack of understanding of the neurobiological mechanisms that drive toxic effects of cadmium in bone, the purpose of this study was to characterize a preclinical model of chronic cadmium exposure. Adult male C57BL/6 J mice were exposed to cadmium 25 mg/L (as CdCl2) in drinking water for 16 weeks. During this time, pain-related behaviors including hindpaw mechanical sensitivity and vertical rears were evaluated every four weeks. We assessed changes in bone microarchitecture at the femoral neck and L5 vertebra by microcomputed tomography and quantified the density of nerve fibers expressing PGP 9.5 (a pan-neuronal marker) and CGRP (a marker of sensory nerve fibers subfamily) at the femoral neck and glabrous skin of the hindpaw using immunohistochemistry. Cadmium exposure produced mechanical hypersensitivity in both hindpaws along with decreased rearing activity (surrogate for musculoskeletal-related pain) without affecting the horizontal activity (a measure of locomotor behavior) in comparison to the control group. Intraperitoneal acute treatment with morphine and gabapentin reversed pain-related behaviors in cadmium-exposed mice. Furthermore, exposure to cadmium resulted in significant trabecular bone deterioration at the femoral neck and L5 vertebra. We also observed a significant reduction in the density of both CGRP+ and PGP 9.5+ nerve fibers in the femoral neck, but not in the hindpaw glabrous skin, suggesting tissue-dependent neurotoxicity. This model may help in developing a mechanism-based understanding of the factors that generate and maintain musculoskeletal pain and bone loss caused by chronic cadmium exposure and in translating these findings into new therapies for treating cadmium-induced bone toxicity.

A multiethnic whole genome sequencing study to identify novel loci for bone mineral density.

At present, there have only been a few DNA sequencing-based studies to explore the genetic determinants of bone mineral density (BMD). We carried out the largest whole genome sequencing analysis to date for femoral neck and spine BMD (n = 4981), with one of the highest average sequencing depths implemented thus far at 22×, in a multiethnic sample (58% Caucasian and 42% African American) from the Louisiana Osteoporosis Study (LOS). The LOS samples were combined with summary statistics from the GEFOS consortium and several independent samples of various ethnicities to perform GWAS meta-analysis (n = 44 506). We identified 31 and 30 genomic risk loci for femoral neck and spine BMD, respectively. The findings substantiate many previously reported susceptibility loci (e.g. WNT16 and ESR1) and reveal several others that are either novel or have not been widely replicated in GWAS for BMD, including two for femoral neck (IGF2 and ZNF423) and one for spine (SIPA1). Although we were not able to uncover ethnicity specific differences in the genetic determinants of BMD, we did identify several loci which demonstrated sex-specific associations, including two for women (PDE4D and PIGN) and three for men (TRAF3IP2, NFIB and LYSMD4). Gene-based rare variant association testing detected MAML2, a regulator of the Notch signaling pathway, which has not previously been suggested, for association with spine BMD. The findings provide novel insights into the pathophysiological mechanisms of osteoporosis.

Exercise Effects on Bone Mineral Density in Men.

In contrast to postmenopausal women, evidence for a favorable effect of exercise on Bone Mineral Density (BMD) is still limited for men. This might be due to the paucity of studies, but also to the great variety of participants and study characteristics that may dilute study results. The aim of the present systematic review and meta-analysis was to evaluate the effect of exercise on BMD changes with rational eligibility criteria. A comprehensive search of six electronic databases up to 15 March 2021 was conducted. Briefly, controlled trials ≥6 months that determined changes in areal BMD in men >18 years old, with no apparent diseases or pharmacological therapy that relevantly affect bone metabolism, were included. BMD changes (standardized mean differences: SMD) of the lumbar spine (LS) and femoral neck (FN) were considered as outcomes. Twelve studies with 16 exercise and 12 control groups were identified. The pooled estimate of random-effect analysis was SMD = 0.38, 95%-CI: 0.14-0.61 and SMD = 0.25, 95%-CI: 0.00-0.49, for LS and FN, respectively. Heterogeneity between the trials was low-moderate. Funnel plots and rank and regression correlation tests indicate evidence for small study publication bias for LS but not FN-BMD. Subgroup analyses that focus on study length, type of exercise and methodologic quality revealed no significant difference between each of the three categories. In summary, we provided further evidence for a low but significant effect of exercise on BMD in men. However, we are currently unable to give even rough exercise recommendations for male cohorts.

A Longitudinal Study of Bone Mineral Accrual during Growth in Competitive Premenarcheal Rhythmic Gymnasts.

The purpose of this investigation was to study whether prolonged competitive rhythmic gymnastics training influenced bone mineral accrual in premenarcheal girls. Eighty-nine girls (45 rhythmic gymnasts [RG] and 44 untrained controls [UC]) between 7 and 9 years of age were recruited and measured annually for four years (not all participants were measured at every occasion). Dual energy x-ray absorptiometry was used to assess the development of whole body (WB), femoral neck (FN) and lumbar spine (LS) bone mineral content (BMC). In addition, body composition, blood adipokine and jumping performance characteristics were obtained. For longitudinal analyses, hierarchical mixed-effects models were constructed to predict differences in the development of WB, FN and LS BMC between RG and UC groups, while accounting for differences in body composition, blood adipokine and jumping performance values. It appeared that from 8 years of age, RG had lower (p < 0.05) fat mass and leptin values, and higher (p < 0.05) jumping performance measures in comparison with UC girls. Hierarchical mixed-effects models demonstrated that RG had 71.9 ± 12.0, 0.23 ± 0.11 and 1.39 ± 0.42 g more (p < 0.05) WB, FN and LS BMC, respectively, in comparison with UC girls. In addition, WB, FN and LS BMC increased more (p < 0.05) between 7 to 12 years of age in RG girls in comparison with UC. In conclusion, these findings suggest that the prolonged exposure to competitive rhythmic gymnastics trainings in premenarcheal girls is associated with greater bone mineral accrual despite lower body fat mass and leptin values.

Exercise attenuates bone mineral density loss during diet-induced weight loss in adults with overweight and obesity: A systematic review and meta-analysis.

BACKGROUND: Weight-loss-induced fat loss improves cardiometabolic health in individuals with overweight and obesity; however, weight loss can also result in bone loss and increased fracture risk. Weight-loss-induced bone loss may be attenuated with exercise. Our aim was to compare changes in bone mineral density (BMD) in adults with overweight and obesity who undertook diet-induced weight loss alone or in combination with exercise. METHODS: We included randomized controlled trials (RCTs) in adults with overweight or obesity (aged ≥18 years; body mass index ≥25 kg/m2) that prescribed diet-induced weight loss alone or in combination with supervised exercise, and measured any bone structural parameters. Risk of bias was assessed using the Cochrane Risk of Bias tool. Random-effects meta-analyses determined mean changes and net mean differences (95% confidence intervals (95%CIs)) in the percentage of areal BMD (aBMD) change between groups. RESULTS: We included 9 RCTs. Diet-induced weight loss led to significant losses in femoral neck aBMD (mean change: -1.73% (95%CI: -2.39% to -1.07%), p < 0.001) and total hip aBMD (-2.19% (95%CI: -3.84% to -0.54%), p = 0.009). Femoral neck aBMD losses were significantly greater in the diet-induced weight loss group compared to the exercise plus diet-induced weight loss group (net difference: -0.88% (95%CI: -1.73% to -0.03%)); however, there were no differences in aBMD changes at any other skeletal site: total hip (-1.96% (95%CI: -4.59% to 0.68%)) and lumbar spine (-0.48% (95%CI: -1.81% to 0.86%)). aBMD changes did not differ significantly according to exercise modality (resistance exercise, aerobic exercise, or a combination of the two) during diet-induced weight loss. CONCLUSION: Diet-induced weight loss led to greater femoral neck bone loss compared to diet-induced weight loss plus exercise. Bone loss at the total hip and lumbar spine was not attenuated by exercise during diet-induced weight loss. The lack of consistent skeletal benefits may be due to the insufficient duration and/or training intensities of most exercise interventions. Additional RCTs with appropriate, targeted exercise interventions should be conducted.

Finite element analysis of femoral neck strains during stair ascent and descent.

For older population, a better understanding of the hip joint loading environment is needed for the prevention of hip pain, and the reduction of the stress fractures and fall risks. Using the motion analysis and inverse dynamics methods, combined with musculoskeletal modelling, static optimization, and finite element (FE) femur model, the difference of femoral neck strains between stair ascent vs. descent, young vs. older populations was compared. A two-way repeated-measures MANOVA was applied to test the effect of age and stair direction on the femoral neck strains. The strains at the femoral neck cross-section were greater for stair descent than ascent for both age groups (mostly P = 0.001 to 0006) but there was no difference between age groups. In this study, femoral neck strains represented bone loading environment in more direct ways than joint reaction forces/moments or joint contact forces, the risk of hip pain, falls and stress fractures might be greater during stair descent than ascent. Possible preventative methods to reduce these risks should be developed in the future studies.

Causal effects of homocysteine levels on the changes of bone mineral density and risk for bone fracture: A two-sample mendelian randomization study.

BACKGROUND & AIMS: Observational studies have demonstrated the relations of homocysteine (HCY) with bone mineral density (BMD) and bone fracture risk, but yielding contradictory results. The present study was conducted to evaluate whether the genetically predicted plasma HCY levels were causally associated with the change of BMD and the risk of bone fracture. METHODS: Genetic summary statistics were extracted from genome-wide association study (GWAS) meta-analysis of plasma HCY levels (n = 44,147), GWAS meta-analyses of measured forearm (FA), femoral neck (FN) and lumbar spine (LS) BMD (n = up to 32,735), UK Biobank estimated heel BMD (eBMD) (n = 426,824) and fracture (n = 426,795) GWAS data. Two Sample Mendelian Randomization (TSMR) analysis was performed to assess the causal effects of genetically determined plasma HCY on the BMD and bone fractures. RESULTS: The MR analysis indicated that, genetically decreased plasma HCY was associated with the increased FA-BMD based on the inverse variance weighting (IVW) method (standard deviation [SD] = 0.348, 95% CI: 0.146 to 0.550, P = 7 × 10-4). However, there were no significant associations of genetically decreased plasma HCY with FN-BMD, LS-BMD, eBMD and the risk for bone fracture (SD = -0.041, 95% CI: -0.189 to 0.106, P = 0.582; SD = -0.053, 95% CI: -0.238 to 0.131, P = 0.572; SD = -0.030, 95% CI: -0.090 to 0.030, P = 0.328, odds ratio [OR]: 1.03, 95% CI: 0.94 to 1.13, P = 0.562, respectively). Moreover, the results also found that genetically determined HCY increase was not correlated with the changes of BMD and the risk for bone fracture. CONCLUSION: Our study revealed that genetically decreased plasma HCY was associated with increase of FA-BMD.

Pathways linking activity, adiposity, and inflammation to bone mineral density in women and men from NHANES 2007 to 2010.

OBJECTIVES: Age, sedentary activity, central adiposity, and inflammation have all been independently associated with bone mineral density (BMD). We assessed how the effects of sedentary activity and central adiposity on BMD of the lumbar spine and femoral neck change across early to late adulthood and whether these relationships are mediated by inflammation. METHODS: We analyzed data from 7135 women and men 20 years of age and older from NHANES 2007 to 2010. Anthropometrics, sedentary activity (min/day), serum CRP (mg/dl), and BMD (gm/cm2 measured by DXA scans) at the femoral neck and lumbar spine. Data were compared by age and sex groups and through causal mediation analysis. RESULTS: The effect of waist circumference on BMD was significantly mediated by serum CRP at both skeletal sites in men and at the femoral neck in women. Sedentary activity did not have a direct relationship to BMD but was mediated by waist circumference in men. Least square means differed significantly by sex and age groups with a general age-related decline in BMD at both skeletal sites. CONCLUSIONS: We found that central adiposity, independent of overall body size and composition as measured through BMI, has an inverse relationship with BMD that is mediated by serum CRP. In addition, the negative impact of increased sedentism acted through changes in central adiposity (waist circumference) but only in men. Although low bone density and osteoporosis are often considered degenerative diseases that primarily impact postmenopausal women, our findings show that sedentary activity and central adiposity impact bone density beginning in early adulthood in both women and men.

Femoral neck strain prediction during level walking using a combined musculoskeletal and finite element model approach.

Recently, coupled musculoskeletal-finite element modelling approaches have emerged as a way to investigate femoral neck loading during various daily activities. Combining personalised gait data with finite element models will not only allow us to study changes in motion/movement, but also their effects on critical internal structures, such as the femur. However, previous studies have been hampered by the small sample size and the lack of fully personalised data in order to construct the coupled model. Therefore, the aim of this study was to build a pipeline for a fully personalised multiscale (body-organ level) model to investigate the strain levels at the femoral neck during a normal gait cycle. Five postmenopausal women were included in this study. The CT and MRI scans of the lower limb, and gait data were collected for all participants. Muscle forces derived from the body level musculoskeletal models were used as boundary constraints on the finite element femur models. Principal strains were estimated at the femoral neck region during a full gait cycle. Considerable variation was found in the predicted peak strain among individuals with mean peak first principal strain of 0.24% ± 0.11% and mean third principal strain of -0.29% ± 0.24%. For four individuals, two overall peaks of the maximum strains were found to occur when both feet were in contact with the floor, while one individual had one peak at the toe-off phase. Both the joint contact forces and the muscular forces were found to substantially influence the loading at the femoral neck. A higher correlation was found between the predicted peak strains and the gluteus medius (R2 ranged between 0.95 and 0.99) than the hip joint contact forces (R2 ranged between 0.63 and 0.96). Therefore, the current findings suggest that personal variations are substantial, and hence it is important to consider multiple subjects before deriving general conclusions for a target population.

A novel method for quantifying femoral neck anteversion: A case study in extinct and extant sloths.

Extinct sloths represent a wide range of morphological, locomotor, and body size variation. Researchers have examined femoral neck angle in two dimensions to hypothesize locomotor behaviors in this group; however, this measure does not account for femoral neck anteversion. Here, we present a new method for quantifying femoral neck anteversion angle, in addition to femoral neck angle, to capture the 3D position of the femoral head/neck. Femora of extant (n = 21; Bradypus and Choloepus) and extinct (n = 49; Acratocnus, Megalocnus, Neocnus, and Parocnus) sloths were surface scanned and their surface models used to calculate three angles of femoral neck anteversion and femoral neck angle. Femoral neck anteversion was calculated as the angle between the femoral neck axis and the geometric axis of the femoral condyles (GA), the 35% cross section axis, and a trochanter axis. Femoral neck angle was calculated as the angle between the femoral neck and shaft axes. Genera were compared using ANOVAs with post hoc multiple comparisons for each angle. Femoral neck angle and femoral neck anteversion relative to the cross section were also analyzed. Significant differences among genera exist for all angles, (p < .001) but not all angles separate all genera. Femoral neck and anteversion angles typically yield different results, demonstrating the utility of analyzing both angles. The GA and cross section angles are highly correlated in sloths, with the exception of comparisons among Megalocnus, Parocnus, and Neocnus, suggesting morphological variation in the distal femur. While this method was applied to sloths, it has broad applicability to mammalian groups.

Globular structure of the hypermineralized tissue in human femoral neck.

Bone becomes more fragile with ageing. Among many structural changes, a thin layer of highly mineralized and brittle tissue covers part of the external surface of the thin femoral neck cortex in older people and has been proposed to increase hip fragility. However, there have been very limited reports on this hypermineralized tissue in the femoral neck, especially on its ultrastructure. Such information is critical to understanding both the mineralization process and its contributions to hip fracture. Here, we use multiple advanced techniques to characterize the ultrastructure of the hypermineralized tissue in the neck across various length scales. Synchrotron radiation micro-CT found larger but less densely distributed cellular lacunae in hypermineralized tissue than in lamellar bone. When examined under FIB-SEM, the hypermineralized tissue was mainly composed of mineral globules with sizes varying from submicron to a few microns. Nano-sized channels were present within the mineral globules and oriented with the surrounding organic matrix. Transmission electron microscopy showed the apatite inside globules were poorly crystalline, while those at the boundaries between the globules had well-defined lattice structure with crystallinity similar to the apatite mineral in lamellar bone. No preferred mineral orientation was observed both inside each globule and at the boundaries. Collectively, we conclude based on these new observations that the hypermineralized tissue is non-lamellar and has less organized mineral, which may contribute to the high brittleness of the tissue.

Physical Activity Throughout Adolescence and Peak Hip Strength in Young Adults.

Importance: Peak bone strength, which occurs in early adulthood, is an important marker of the future risk of osteoporosis. It is therefore important to identify modifiable early life factors that are associated with the attainment of peak hip strength. Objective: To investigate the association of time spent in moderate to vigorous-intensity and light-intensity physical activity throughout adolescence with peak hip strength in adulthood. Design, Setting, and Participants: The Avon Longitudinal Study of Parents and Children is a prospective birth cohort study that initially recruited all pregnant women residing within the catchment area of 3 health authorities in southwest England who had an expected delivery date between April 1, 1991, and December 31, 1992. In total, 15 454 eligible pregnant women were enrolled, and 15 589 infants were delivered. Of those, 14 901 infants were alive at age 1 year. The present analysis examined 2569 healthy offspring who had valid physical activity measurements obtained during a clinical assessment for at least 1 age (12, 14, 16, and/or 25 years), with up to 4 repeated accelerometer assessments performed (1 per age-associated clinical visit). Data were analyzed from June 2019 to June 2020. Exposures: Trajectories of accelerometer-assessed time spent in moderate to vigorous-intensity and light-intensity physical activity at ages 12, 14, 16, and 25 years (measured in minutes per day) were identified using latent trajectory modeling. Moderate to vigorous-intensity and light-intensity physical activity were determined using established thresholds of acceleration counts per minute. Main Outcomes and Measures: Femur neck bone mineral density (BMD; measured in g/cm2) at age 25 years assessed by dual-energy radiography absorptiometry scans of the hip. Results: A total of 2569 participants (1588 female participants [62%]) were included in the analysis. Male participants spent more time in moderate to vigorous-intensity activity at each age and had greater adult femur neck BMD than female participants. For each sex, 3 moderate to vigorous-intensity trajectory subgroups and 3 light-intensity trajectory subgroups were identified. With regard to the moderate to vigorous-intensity trajectories, most male participants (85%) were in the low adolescent subgroup, with only 6% and 9% in the high early-adolescent and high mid-adolescent subgroups, respectively. Moderate to vigorous-intensity trajectories in female participants were divided into low adolescent-low adult (73%), low adolescent-high adult (8%), and high adolescent (19%) subgroups. Light-intensity physical activity trajectories were classified into low nonlinear, moderate decreasing, and high decreasing subgroups for both sexes. Femur neck BMD in male participants was greater in the high early-adolescent subgroup (0.38 g/cm2; 95% CI, 0.11-0.66 g/cm2) and the high mid-adolescent subgroup (0.33 g/cm2; 95% CI, 0.07-0.60 g/cm2) compared with the low adolescent (reference) subgroup. Femur neck BMD in female participants was greater in the high adolescent subgroup (0.28 g/cm2; 95% CI, 0.15-0.41 g/cm2) but not in the low adolescent-high adult subgroup (-0.12 g/cm2; 95% CI, -0.44 to 0.20 g/cm2) compared with the low adolescent-low adult (reference) subgroup. A sensitivity analysis using a negative-outcome control variable to explore unmeasured confounding supported these findings. The light-intensity trajectories were not associated with femur neck BMD; for example, differences in femur neck BMD between the high decreasing and low nonlinear subgroups were 0.16 g/cm2 (95% CI, -0.08 to 0.40 g/cm2) in male participants and 0.20 g/cm2 (95% CI, -0.05 to 0.44 g/cm2) in female participants. Conclusions and Relevance: Supporting high-intensity physical activity throughout early life may help to maximize peak hip strength and prevent osteoporosis in later life. Replication of our findings in independent studies will be important.