Femoral Strength Research Articles

Associations between blood antioxidant levels and femoral neck strength

BackgroundStudies have confirmed that antioxidants contribute to a lower risk of osteoporosis, which is an independent factor for femoral neck fracture (FNF). However, the associations between blood antioxidant levels and femoral neck strength remain unclear.ObjectiveOur aim was to test the hypothesis that levels of blood antioxidants are positively associated with composite indices of bone strength in femoral neck, which integrate the bending strength index (BSI), compressive strength index (CSI), and impact strength index (ISI), in a population of middle-aged and elderly individuals.MethodsThis cross-sectional study utilized data from the Midlife in the United States (MIDUS) study. Blood levels of antioxidants were measured and analyzed.ResultsIn total, data from 878 participants were analyzed. Results of Spearman correlation analyses indicated that blood levels of 6 antioxidants (total lutein, zeaxanthin, alpha-carotene, 13-cis-beta-carotene, trans-beta-carotene and total lycopene) were positively associated with CSI, BSI, or ISI in middle-aged and elderly individuals. Conversely, blood gamma-tocopherol and alpha-tocopherol levels were negatively associated with CSI, BSI, or ISI scores. Furthermore, linear regression analyses suggested that only blood zeaxanthin levels remained positively associated with CSI (odds ratio, OR 1.27; 95% CI: 0.03, 2.50; p = 0.045), BSI (OR, 0.54; 95% CI: 0.03–1.06; p = 0.037), and ISI (OR, 0.06; 95% CI: 0.00, 0.13; p = 0.045) scores in the study population after adjusting for age and sex.ConclusionsOur results indicated that elevated blood zeaxanthin levels were significantly and positively associated with femoral neck strength (CSI, BSI, or ISI) in a population of middle-aged and elderly individuals. These findings suggest that zeaxanthin supplementation may reduce FNF risk independently.

Femur 3D-DXA Assessment in Female Football Players, Swimmers, and Sedentary Controls.

Cortical and trabecular volumetric bone mineral density (vBMD), cortical thickness and surface BMD (sBMD, density-to-thickness ratio) were analyzed in the proximal femur of elite female football players and artistic swimmers using three-dimensional dual-energy X-ray absorptiometry (3D-DXA) software and compared to sedentary controls. Football players had significantly higher (p<0.05) vBMD (mg/cm3) in the trabecular (263±44) and cortical femur (886±69) than artistic swimmers (224±43 and 844±89) and sedentary controls (215±51 and 841±85). Football players had also higher (p<0.05) cortical thickness (2.12±0.19 mm) and sBMD (188±22 mg/cm2) compared to artistic swimmers (1.85±0.15 and 156±21) and sedentary controls (1.87±0.16 and 158±23). Artistic swimmers did not show significant differences in any parameter analyzed for 3D-DXA when compared to sedentary controls. The 3D-DXA modeling revealed statistical differences in cortical thickness and vBMD between female athletes engaged in weight-bearing (football) and non-weight bearing (swimming) sports and did not show differences between the non-weight bearing sport and the sedentary controls. 3D-DXA modeling could provide insight into bone remodeling in the sports field, allowing evaluation of femoral trabecular and cortical strength from standard DXA scans.

The Effects of a 1-Year Recreational Football Protocol on Bone Health Parameters in a Group of Healthy Inactive 50-Year-Old Men

The main aim of the current study was to explore the effects of a 1-year recreational football protocol on bone health parameters (bone mineral content (BMC), bone mineral density (BMD), femoral neck geometry and composite indices of femoral neck strength) in a group of healthy inactive 50-year-old men. 51 middle-aged men voluntarily participated in this study, but only 41 of them completed it. Thus, the study population included 11 former football (FF) players and 30 inactive men. Inactive men were assigned to 3 different groups: controls (n=10), recreational football 30 (RF30; n=10) and recreational football 60 (RF60; n=10). The RF30 group performed two sessions of recreational football per week; the duration of each session was 30 minutes. The RF60 group performed two sessions of recreational football per week; the duration of each session was 60 minutes. The current study has demonstrated that whole body (WB) BMC, femoral neck BMD, cross-sectional moment of inertia, compression strength index, bending strength index and impact strength index increased in both experimental groups (RF30 and RF60) but not in the control group. The percentages of variations in bone health parameters were not significantly different between RF30 and RF60. In conclusion, this study suggests that recreational football is an effective method to improve bone health parameters in middle-aged men. In the studied population, most of the bone health benefits occurred after a low volume training protocol (2 * 30 minutes of recreational football per week).

2D-3D reconstruction of the proximal femur from DXA scans: Evaluation of the 3D-Shaper software.

Introduction: Osteoporosis is currently diagnosed based on areal bone mineral density (aBMD) computed from 2D DXA scans. However, aBMD is a limited surrogate for femoral strength since it does not account for 3D bone geometry and density distribution. QCT scans combined with finite element (FE) analysis can deliver improved femoral strength predictions. However, non-negligible radiation dose and high costs prevent a systematic usage of this technique for screening purposes. As an alternative, the 3D-Shaper software (3D-Shaper Medical, Spain) reconstructs the 3D shape and density distribution of the femur from 2D DXA scans. This approach could deliver a more accurate estimation of femoral strength than aBMD by using FE analysis on the reconstructed 3D DXA. Methods: Here we present the first independent evaluation of the software, using a dataset of 77 ex vivo femora. We extend a prior evaluation by including the density distribution differences, the spatial correlation of density values and an FE analysis. Yet, cortical thickness is left out of this evaluation, since the cortex is not resolved in our FE models. Results: We found an average surface distance of 1.16mm between 3D DXA and QCT images, which shows a good reconstruction of the bone geometry. Although BMD values obtained from 3D DXA and QCT correlated well (r 2 = 0.92), the 3D DXA BMD were systematically lower. The average BMD difference amounted to 64mg/cm3, more than one-third of the 3D DXA BMD. Furthermore, the low correlation (r 2 = 0.48) between density values of both images indicates a limited reconstruction of the 3D density distribution. FE results were in good agreement between QCT and 3D DXA images, with a high coefficient of determination (r 2 = 0.88). However, this correlation was not statistically different from a direct prediction by aBMD. Moreover, we found differences in the fracture patterns between the two image types. QCT-based FE analysis resulted mostly in femoral neck fractures and 3D DXA-based FE in subcapital or pertrochanteric fractures. Discussion: In conclusion, 3D-Shaper generates an altered BMD distribution compared to QCT but, after careful density calibration, shows an interesting potential for deriving a standardized femoral strength from a DXA scan.

Effects of Supplementation of 25-Hydroxyvitamin D3 as a Vitamin D3 Substitute on Performance, Bone Traits, and Egg Quality of Laying Hens from 1 Day to 72 Weeks of Age

This experiment was conducted to explore the effect of long-term supplementation of 25-hydroxyvitamin D3 (25-OHD) as a vitamin D3 (VD3) substitute on performance, bone traits, and egg quality of laying hens from 1 day to 72 weeks of age. In total, 900 one-day-old Lohman pullets were randomly allotted into three dietary groups (three treatments × 15 replicates × 20 birds per replicate): VD3 2800 IU/kg; 25-OHD 69 μg/kg; 25-OHD 125 μg/kg. At the end of the 20th w, five replicates from each group were selected to feed on the same vitamin D diets, as used during the rearing stage (1–20 w) until 72 w. The result showed that the 25-OHD 125 μg/kg treatment had the lowest average daily feed intake (ADFI) at 1–8 or 1–19 w, body weight at 8 w, body weight gain between 1 and 8 w and shank length at 4 w (p &lt; 0.05). The 25-OHD 125 μg/kg treatment had a lower shank length at 7 w, compared with the 25-OHD 69 μg/kg treatment. The shank length of the birds in each treatment reached the maximum (about 103 mm) at about 18 w of age. For the bone traits, the 25-OHD 125 μg/kg treatment had the lowest femur bone diameter at 20 w (p &lt; 0.001) and femur bone plumpness at 20 w (p = 0.002). The 25-OHD 125 μg/kg treatment had a lower tibia strength at 10 w (p = 0.023) and keel length at 10 w (p = 0.046), compared with the 25-OHD 69 μg/kg treatment. However, both 25-OHD 69 and 125 μg/kg treatments had a greater femur strength at 72 w (p = 0.006), compared with the VD3 2800 IU/kg treatment. No difference in laying performance was observed among all treatments. The overall (21–72 w) ADFI in the 25-OHD 125 μg/kg treatment was significantly lower than that in the 25-OHD 69 μg/kg treatment (p = 0.030). At 60 w, the 25-OHD 125 μg/kg treatment had a lower eggshell thickness (p = 0.012) and proportion of eggshell (p = 0.022), compared with the 25-OHD 69 μg/kg treatment. No significant differences in egg quality parameters were observed at 50 and 70 w among treatments. In general, supplementary 2800 IU/kg doses of VD3 at the early stage were sufficient to maintain the bone quality and growth and development of pullets. Feeding birds at a higher 25-OHD level (125 μg/kg) resulted in the reduced ADFI and growth at the rearing period, but the long-term supplementation of 25-OHD as a VD3 substitute improved the bone quality in the late laying period.

Modification to Mirels scoring system location component improves fracture prediction for metastatic disease of the proximal femur

BackgroundCorrectly identifying patients at risk of femoral fracture due to metastatic bone disease remains a clinical challenge. Mirels criteria remains the most widely referenced method with the advantage of being easily calculated but it suffers from poor specificity. The purpose of this study was to develop and evaluate a modified Mirels scoring system through scoring modification of the original Mirels location component within the proximal femur.MethodsComputational (finite element) experiments were performed to quantify strength reduction in the proximal femur caused by simulated lytic lesions at defined locations. Virtual spherical defects representing lytic lesions were placed at 32 defined locations based on axial (4 axial positions: neck, intertrochanteric, subtrochanteric or diaphyseal) and circumferential (8 circumferential: 45-degree intervals) positions. Finite element meshes were created, material property assignment was based on CT mineral density, and femoral head/greater trochanter loading consistent with stair ascent was applied. The strength of each femur with a simulated lesion divided by the strength of the intact femur was used to calculate the Location-Based Strength Fraction (LBSF). A modified Mirels location score was next defined for each of the 32 lesion locations with an assignment of 1 (LBSF > 75%), 2 (LBSF: 51–75%), and 3 (LBSF: 0–50%).To test the new scoring system, data from 48 patients with metastatic disease to the femur, previously enrolled in a Musculoskeletal Tumor Society (MSTS) cross-sectional study was used. The lesion location was identified for each case based on axial and circumferential location from the CT images and assigned an original (2 or 3) and modified (1,2, or 3) Mirels location score. The total score for each was then calculated. Eight patients had a fracture of the femur and 40 did not over a 4-month follow-up period. Logistic regression and decision curve analysis were used to explore relationships between clinical outcome (Fracture/No Fracture) and the two Mirels scoring methods.ResultsThe location-based strength fraction (LBSF) was lowest for lesions in the subtrochanteric and diaphyseal regions on the lateral side of the femur; lesions in these regions would be at greatest risk of fracture. Neck lesions located at the anterior and antero-medial positions were at the lowest risk of fracture. When grouped, neck lesions had the highest LBSF (83%), followed by intertrochanteric (72%), with subtrochanteric (50%) and diaphyseal lesions (49%) having the lowest LBSF. There was a significant difference (p < 0.0001) in LBSF between each axial location, except subtrochanteric and diaphyseal which were not different from each other (p = 0.96).The area under the receiver operator characteristic (ROC) curve using logistic regression was greatest for modified Mirels Score using site specific location of the lesion (Modified Mirels-ss, AUC = 0.950), followed by a modified Mirels Score using axial location of lesion (Modified Mirels-ax, AUC = 0.941). Both were an improvement over the original Mirels score (AUC = 0.853).Decision curve analysis was used to quantify the relative risks of identifying patients that would fracture (TP, true positives) and those erroneously predicted to fracture (FP, false positives) for the original and modified Mirels scoring systems. The net benefit of the scoring system weighed the benefits (TP) and harms (FP) on the same scale. At a threshold probability of fracture of 10%, use of the modified Mirels scoring reduced the number of false positives by 17–20% compared to Mirels scoring.ConclusionsA modified Mirels scoring system, informed by detailed analysis of the influence of lesion location, improved the ability to predict impending pathological fractures of the proximal femur for patients with metastatic bone disease. Decision curve analysis is a useful tool to weigh costs and benefits concerning fracture risk and could be combined with other patient/clinical factors that contribute to clinical decision making.

Biomechanical analysis analyzing association between bone mineral density and lag screw migration

A proximal femoral nail using a helical blade (HB) is commonly utilized to treat proximal femoral fracture but cut through failure of the lag screws is one of the devastating complications following the surgery. While controversial, one of the potential risk factors for cut through failure is poor bone strength which can be predicted by measuring bone mineral density (BMD). In this study, we performed a biomechanical test on the fractured femoral head to validate whether the indirectly measured BMD from the contralateral hip or that measured directly from the retrieved femoral head can elucidate the structural strength of the fractured femoral head and thereby can be used to predict migration of lag screws. Our result showed that directly measured BMD has a significant correlation with the HB migration on the osteoporotic femoral head. However, while the BMDs measured from the contralateral femoral neck or total hip is the most widely used parameter to predict the bone strength of the fractured femur, this may have limited usability to predict HB migration.

The predictive ability of a QCT-FE model of the proximal femoral stiffness under multiple load cases is strongly influenced by experimental uncertainties

Despite significant improvements in terms of the predictive ability of Quantitative Computed Tomography based Finite Element (QCT-FE) models in estimating femoral strength (fracture load and stiffness), no substantial clinical adoption of this method has taken place to date. Narrowing the wide variability of FE results by standardizing the methodology and validation protocols, as well as reducing the uncertainties in the FEA process have been proposed as routes towards improved reliability. The aim of this study was to: First, validate a QCT-FE model of proximal femoral stiffness in multiple stance load cases, and second, using a parametric approach, determine the influence of select experimental and modeling parameters on the predictive ability of our model. Ten fresh frozen human femoral samples were tested in neutral stance, 15° adducted and 15° abducted load cases. Voxel-based linear-elastic QCT-FE models of the samples were generated to predict the models’ stiffness values in all load cases. The base FE models were validated against the experimental results using linear regression. Thirty six deviated models were created using the minimum and maximum values of experiment-based “plausible range” for 18 parameters in 4 categories of embedding, loading, material, and segmentation. The predictive ability of the models were compared in terms of the coefficient of determination (R2) of the linear regression between the measured and predicted stiffness values in all load cases. Our model was capable of capturing 90% of the variation in the experimental stiffness of the samples in neutral stance position (R2 = 0.9, concordance correlation coefficient (CCC) = 0.93, percent root mean squared error (RMSE%) = 8.4%, slope and intercept not significantly different from unity and zero, respectively). Embedding and loading categories strongly affected the predictive ability of the models with an average percent difference in R2 of 4.36% ± 2.77 and 2.96% ± 1.69 for the stance-neutral load case, respectively. The performance of the models were significantly different in adducted and abducted load cases with their R2 dropping to 71% and 70%, respectively. Similarly, off-axes load cases were affected by the parameters differently compared to the neutral load case, with the loading parameter category imposing more than 10% difference on their R2, larger than all other categories. We also showed that automatically selecting the best performing plausible value for each parameter and each sample would result in a perfectly linear correlation (R2> 0.99) between the “tuned” model’s predicted stiffness and experimental results. Based on our results, high sensitivity of the model performance to experimental parameters requires extra diligence in modeling the embedding geometry and the loading angles since these sources of uncertainty could dwarf the effects of material modeling and image processing parameters. The results of this study could help in improving the robustness of the QCT-FE models of proximal femur by limiting the uncertainties in the experimental and modeling steps.

Dietary 25-hydroxy-cholecalciferol and additional vitamin E improve bone development and antioxidant capacity in high-density stocking broilers.

This study aimed to investigate the effects of diets supplemented with 25-hydroxycholecalciferol [25-(OH)D3] and additional vitamin E on growth performance, antioxidant capacity, bone development, and carcass characteristics at different stocking densities on commercial broiler farms. A total of 118,800 one-day-old Arbor Acres broilers were assigned to a 2 × 2 factorial treatment consisting of two dietary vitamin levels (5,500 IU vitamin D3 and 60 IU vitamin E: normal diet, using half 25-(OH)D3 as a source of vitamin D3 and an additional 60 IU of vitamin E: 25-(OH)D3+VE diet) and two stocking densities (high density of 20 chickens/m2: HD and 16 chickens/m2: LD). The experiment lasted for 42 d. The results showed that high-density stocking negatively affected the growth performance of broilers during the first four weeks, whereas the vitamin diet treatment significantly improved the feed conversion ratios (FCR) during the last 2 wk. Vitamin diets increased catalase at 14 and 42 d, and the glutathione peroxidase (GSH-px) levels at 42 d in high-density-stocked broilers. The interaction showed that serum vitamin E levels were significantly improved at 28 d of age in high-density-stocked broilers as a result of the vitamin diets. Stocking density and dietary treatments were found to significantly affect bone development, with the vitamin diet significantly increasing metatarsal length and femoral bone strength in broilers from high-density stocking density at 28 d of age. High stocking density increased the proportion of leg muscles and meat yield per square meter. In general, 25-(OH)D3 and additional vitamin E suppressed oxidative stress and ameliorated the negative effects of high-density stocking on bone development in a commercial chicken farm setting. Vitamin diets improved the FCR of broilers, while high-density stocking resulted in better economic outcomes.

Finite Element Model-Computed Mechanical Behavior of Femurs with Metastatic Disease Varies Between Physiologic and Idealized Loading Simulations.

Femurs affected by metastatic bone disease (MBD) frequently undergo surgery to prevent impending pathologic fractures due to clinician-perceived increases in fracture risk. Finite element (FE) models can provide more objective assessments of fracture risk. However, FE models of femurs with MBD have implemented strain- and strength-based estimates of fracture risk under a wide variety of loading configurations, and "physiologic" loading models typically simulate a single abductor force. Due to these variations, it is currently difficult to interpret mechanical fracture risk results across studies of femoral MBD. Our aims were to evaluate (1) differences in mechanical behavior between idealized loading configurations and those incorporating physiologic muscle forces, and (2) differences in the rankings of mechanical behavior between different loading configurations, in FE simulations to predict fracture risk in femurs with MBD. We evaluated 9 different patient-specific FE loading simulations for a cohort of 54 MBD femurs: strain outcome simulations-physiologic (normal walking [NW], stair ascent [SA], stumbling), and joint contact only (NW contact force, excluding muscle forces); strength outcome simulations-physiologic (NW, SA), joint contact only, offset torsion, and sideways fall. Tensile principal strain and femur strength were compared between simulations using statistical analyses. Tensile principal strain was 26% higher (R 2 = 0.719, P < .001) and femur strength was 4% lower (R 2 = 0.984, P < .001) in simulations excluding physiologic muscle forces. Rankings of the mechanical predictions were correlated between the strain outcome simulations (ρ = 0.723 to 0.990, P < .001), and between strength outcome simulations (ρ = 0.524 to 0.984, P < .001). Overall, simulations incorporating physiologic muscle forces affected local strain outcomes more than global strength outcomes. Absolute values of strain and strength computed using idealized (no muscle forces) and physiologic loading configurations should be used within the appropriate context when interpreting fracture risk in femurs with MBD.

Prevalence of osteoporosis in older male veterans receiving hip-containing computed tomography scans: opportunistic use of biomechanical computed tomography analysis (BCT)

SummaryOsteoporosis care in men is suboptimal due to low rates of testing and treatment. Applying biomechanical computed tomography (BCT) analysis to existing CT scans, we found a high proportion of men with osteoporosis have never been diagnosed or treated. BCT may improve identification of patients at high risk of fracture.PurposeOsteoporosis care in men is suboptimal due to low rates of DXA testing and treatment. Biomechanical computed tomography analysis (BCT) can be applied “opportunistically” to prior hip-containing CT scans to measure femoral bone strength and hip BMD.MethodsIn this retrospective, cross-sectional study, we used BCT in male veterans with existing CT scans to investigate the prevalence of osteoporosis, defined by hip BMD (T-score ≤ − 2.5) or fragile bone strength (≤ 3500 N). 577 men, age ≥ 65 with abdominal/pelvic CTs performed in 2017–2019, were randomly selected for BCT analysis. Clinical data were collected via electronic health records and used with the femoral neck BMD T-score from BCT to estimate 10-year hip fracture risks by FRAX.ResultsPrevalence of osteoporosis by BCT increased with age (13.5% age 65–74; 18.2% age 75–84; 34.3% age ≥ 85), with an estimated overall prevalence of 18.3% for men age ≥ 65. In those with osteoporosis (n = 108/577), only 38.0% (41/108) had a prior DXA and 18.6% (7/108) had received osteoporosis pharmacotherapy. Elevated hip fracture risk by FRAX (≥ 3%) did not fully capture those with fragile bone strength. In a multivariate logistic regression model adjusted for age, BMI, race, and CT location, end stage renal disease (odds ratio 7.4; 95% confidence interval 2.3–23.9), COPD (2.2; 1.2–4.0), and high-dose inhaled corticosteroid use (3.7; 1.2–11.8) were associated with increased odds of having osteoporosis by BCT.ConclusionOpportunistic BCT in male veterans provides an additional avenue to identify patients who are at high risk of fractures.

Addressing local bone loss in the proximal femurs of women at high risk of fracture

Proximal femoral fractures in older women are a worldwide leading cause of morbidity and mortality and a public health problem. Although pharmacological therapies can improve bone mineral density (BMD) and reduce fracture risk, current efforts are focused on researching a procedure that guarantees both immediate and long-lasting effectiveness over time. The AGN1 local osteo-enhancement procedure is a recently developed bone augmentation procedure. This minimally-invasive surgical approach is used to prepare an enhancement site, the area where new bone is desired within a local bony region weakened by osteoporotic bone loss, and fill it with a triphasic, resorbable, calcium-based implant material. This procedure results in a notable, statistically significant and sustained long-term increase in proximal femur BMD and femoral strength, improving femoral neck resistance to compression and distraction forces acting on it and thereby preventing fall-related fractures.

The biomechanical behavior of 3D printed human femoral bones based on generic and patient-specific geometries

BackgroundBone is a highly complex composite material which makes it hard to find appropriate artificial surrogates for patient-specific biomechanical testing. Despite various options of commercially available bones with generic geometries, these are either biomechanically not very realistic or rather expensive.MethodsIn this work, additive manufacturing was used for the fabrication of artificial femoral bones. These were based on CT images of four different commercially available femoral bone surrogates and three human bones with varying bone density. The models were 3D printed using a low-budget fused deposition modeling (FDM) 3D printer and PLA filament. The infill density was mechanically calibrated and varying cortical thickness was used. Compression tests of proximal femora simulating stance were performed and the biomechanical behavior concerning ultimate force, spring stiffness, and fracture pattern were evaluated as well as compared to the results of commercial and cadaveric bones.ResultsRegarding the ultimate forces and spring stiffness, the 3D printed analogs showed mechanical behavior closer to their real counterparts than the commercially available polyurethan-based surrogates. Furthermore, the increase in ultimate force with increasing bone density observed in human femoral bones could be reproduced well. Also, the fracture patterns observed match well with fracture patterns observed in human hip injuries.ConclusionConsequently, the methods presented here show to be a promising alternative for artificial generic surrogates concerning femoral strength testing. The manufacturing is straightforward, cheap, and patient-specific geometries are possible.

Nordic walking with an integrated resistance shock absorber affects the femur strength and muscles torques in postmenopausal women

Deterioration of the structure and function of the musculoskeletal system represents a significant problem during aging and intervention with a suitable load of physical activity may improve the quality of life. Nordic walking (NW) has become a popular and easily accessible form of activity, especially for older adults people around the world. Thus, the purpose of the study was to evaluate the influence of an Nordic walking training program with classic poles (NW) and with integrated resistance shock absorber (RSA) on bone mineral density and the peak torques of upper limb muscles and to compare the effects of both intervention programs. 25 women were randomly assigned to two training groups: 10 subjects using RSA (68 ± 4.19 years) and 15 subjects using NW poles (65 ± 3.40 years), which completed 8 weeks of training program. The hip, spine and forearm areal bone mineral density, torques of the flexors and extensors at the elbow and shoulder joints were measured before starting the training programs and after their completion. The most significant effect was found in differences between the two groups of women with respect to the femur strength index (p = 0.047) and the ratio of the flexors to extensors in the elbow (p = 0.049) and shoulder (p = 0.001) joints and peak torque of flexors in the shoulder joint (p = 0.001) for the left arm. A significant difference was also found in the index of torque asymmetry of flexors in the shoulder joint (p = 0.002). The study shows that Nordic walking with RSA poles for postmenopausal women led to beneficial changes in the femur strength index. However, we found no significant influence on bone mineral density values measured on the whole body, the femoral neck, forearm or lumbar spine regions. The occurrence of asymmetry in biomechanical muscle parameters, which was observed using RSA poles, may suggest the necessity of systematic controlling the gait technique to avoid the adverse consequences of asymmetrical rotation of the lumbar spine.

Eldecalcitol prevents muscle loss by suppressing PI3K/AKT/FOXOs pathway in orchiectomized mice.

Elderly male patients are susceptible to develop osteoporosis and sarcopenia, especially those with fragility fractures, hypogonadism, and prostate cancer with androgen deprivation therapy. However, at present, very few treatments are available for men with sarcopenia. Previous preclinical studies in ovariectomized rats have shown the promising effects of eldecalcitol in ameliorating the bone strength and muscle atrophy. We thus investigated the effects of eldecalcitol on androgen-deficient male mice. Six-week-old male mice underwent orchiectomy (ORX) or sham surgery. Mice were randomly divided into 4 groups (n = 12/per group), including 1) sham mice, 2) ORX group, 3) ORX eldecalcitol 30ng/kg, and 4) ORX eldecalcitol 50ng/kg. Eldecalcitol increased bone mass and strength of femur in ORX mice. Eldecalcitol 30ng/kg dose completely rescued ORX-induced muscle weakness. The RT-qPCR showed that eldecalcitol enhanced the mRNA levels of type I and IIa fibers. The expression levels of MuRF1 and Atrogin-1 of gastrocnemius in the eldecalcitol groups were much lower than that of the ORX group. It is assumed that eldecalcitol potentially acts via PI3K/AKT/FOXOs signaling pathway. These findings provide evidence for evaluating eldecalcitol as an investigational treatment for male patients with sarcopenia and osteoporosis.

Geometry and bone mineral density determinants of femoral neck strength changes following exercise

Physical exercise induces spatially heterogeneous adaptation in bone. However, it remains unclear where the changes in BMD and geometry have the greatest impact on femoral neck strength. The aim of this study was to determine the principal BMD-and-geometry changes induced by exercise that have the greatest effect on femoral neck strength. Pre- and post-exercise 3D-DXA images of the proximal femur were collected of male participants from the LIFTMOR-M exercise intervention trial. Meshes with element-by-element correspondence were generated by morphing a template mesh to each bone to calculate changes in BMD and geometry. Finite element (FE) models predicted femoral neck strength changes under single-leg stance and sideways fall load. Partial least squares regression (PLSR) models were developed with BMD-only, geometry-only, and BMD-and-geometry changes to determine the principal modes that explained the greatest variation in neck strength changes. The PLSR models explained over 90% of the strength variation with 3 PLS components using BMD-only (R2 > 0.92, RMSE < 0.06 N) and 8 PLS components with geometry-only (R2 > 0.93, RMSE < 0.06 N). Changes in the superior neck and distal cortex were most important during single-leg stance while the superior neck, medial head, and lateral trochanter were most important during a sideways fall. Local changes in femoral neck and head geometry could differentiate the exercise groups from the control group. Exercise interventions may target BMD changes in the superior neck, inferior neck, and greater trochanter for improved femoral neck strength in single-leg stance and sideways fall.

Une nouvelle méthode pour améliorer la stabilité de la bille fémorale sur le pivot en peropératoire lors d’une arthroplastie totale de la hanche – une étude de preuve de concept

BackgroundMechanically assisted crevice corrosion (MACC) has been associated with the compromised durability and fixation of modular total hip implants, adverse reaction of local tissue, and other undesirable clinical outcomes in total hip arthroplasty (THA). MACC is primarily caused by the relative motion between the femoral head and stem. To minimize the relative motion the taper connection between the two components must be strong enough. The current study addressed the following questions: (1) Does increasing the mass of the femoral stem improve the taper connection strength intraoperatively? (2) Does increasing the mass of the femoral stem reduce the risk of periprosthetic tissue damage intraoperatively? HypothesisIncreasing the mass of the femoral stem improve the taper connection strength intraoperatively. Materials and methodsDuring the experiment, femoral heads were impacted onto the stem tapers with and without an additional weight attached to the stem. The femoral heads were then pulled off to investigate the strength of the taper connection. The stem displacement and acceleration at impaction were also measured to evaluate the risk of periprosthetic tissue damage. ResultsThe results showed that the pull-off force was increased by 24% (p=0.011, n=6) when an additional weight was attached to the stem. The additional weight also reduced the maximum stem acceleration and maximum stem displacement by 37% (p<0.001, n=6) and 14% (p=0.094, n=6), respectively. DiscussionThese findings suggest that the femoral head and stem taper connection strength can be significantly improved and the risk of periprosthetic tissue damage significantly reduced intraoperatively by attaching an additional weight to the stem to increase its mass. Level of evidenceIII, comparative in vitro mechanical investigation.

Positive association of lean mass and negative association of protein intake on bone mass and bone geometry of adolescent soccer players

ObjectiveThe aim of this study was to evaluate the association of food consumption and body composition on bone parameters in adolescent soccer players. MethodsThere were 148 male soccer players 12 to 18 y who participated in the study. Body composition was assessed by dual energy x-ray absorptiometry, comprising bone mineral density (BMD) and bone mineral content (BMC) of total body without head (TBLH), lumbar spine (L1-L4), and right femoral neck (RFN). The bone geometry variables measured were femoral strength index (FSI), buckling ratio (BR), section modulus (Z), cross-sectional moment of inertia (CSMI), and cross-sectional area (CSA). Food intake was analyzed using the 24-h food recall. Somatic maturation was estimated by the peak height velocity equation. For the statistical analysis, the stepwise multiple linear regression was used, with P < 0.05. ResultsRegarding food consumption, there was a high protein intake and low calcium intake. Lean mass was a predictor of BMC of TBLH (R2 = 0.524), L1-L4 (R2 = 0.492), and RFN (R2 = 0.405); BMD of L1-L4 (R2 = 0.407) and RFN (R2 = 0.27); Z (R2 = 0.683), CSMI (R2 = 0.630), and CSA (R2 = 0.640). There was a negative correlation between protein intake with bone mass and bone geometry parameters. ConclusionIn adolescent soccer players, lean mass was a predictor of bone parameters, and high protein intake was negatively associated with bone mass and geometry.

Effect of screw tunnels on proximal femur strength after screw removal: A finite element analysis

BackgroundThe presence of screw tunnels in the femoral neck is a problem for patients with proximal femoral fractures after removal of internal fixation. The question of how much does the existence of the screw tunnels affect the strength of the femur and whether the patient needs to be protected with an adjunctive device has been controversial. The objective of this finite element analysis was to determine (1) whether the screw tunnels affects normal weight bearing after removal of internal fixation of a proximal femur fracture, (2) which screw tunnels parameters affect the weight bearing capacity of the entire femur. HypothesisThe presence of the screw tunnels reduces the load-bearing capacity of the femur, and the arrangement, diameter and wall thickness of the screw tunnels affect the load-bearing capacity of the femur. Materials and methodsTwenty patients who underwent surgical treatment for proximal femur fracture at our hospital were included in the study. Computed tomography (CT) values of the screw tunnel wall in the femur after removal of internal fixations were analysed. Mimics v16.0 and Hypermesh v13.0 software programs were used to generate 3-dimensional (3D) tetrahedral finite element models of the proximal femur with different screw tunnel numbers, diameters, thicknesses, and arrangements. An acetabulum exerting a vertical pressure load of 600N on the femoral head was simulated and the force on various parts of the femur in each model was calculated. ResultsThere was no difference in the Hounsfield Units of the tunnel walls and cortical bone of the proximal femur (893.48±61.28 vs. 926.34±58.43; p=0.091). In each of the 3D models, the cancellous bone was the first structure to reach maximal stress. The compressive strength of the femur decreased with increasing thickness of the screw tunnel wall and decreased with increasing tunnel diameter. The femoral neck model with the inverted triangle screw tunnel arrangement had the highest compressive strength. DiscussionThe femoral neck with screw tunnels can withstand day-to-day stress without special intervention. For femoral neck fractures fixed with cannulated screws, inverted triangle screws are recommended; For a single screw tunnel in the femoral neck, the larger the diameter of the femoral neck internal screw channel, the weaker the load-bearing capacity of the femur. Level of evidenceIII; well-designed computational non-experimental study.

Statistical Properties of a Virtual Cohort for In Silico Trials Generated with a Statistical Anatomy Atlas

Osteoporosis-related hip fragility fractures are a catastrophic event for patient lives but are not frequently observed in prospective studies, and therefore phase III clinical trials using fractures as primary clinical endpoint require thousands of patients enrolled for several years to reach statistical significance. A novel answer to the large number of subjects needed to reach the desired evidence level is offered by In Silico Trials, that is, the simulation of a clinical trial on a large cohort of virtual patients, monitoring the biomarkers of interest. In this work we investigated if statistical aliasing from a custom anatomy atlas could be used to expand the patient cohort while retaining the original biomechanical characteristics. We used a pair-matched cohort of 94 post-menopausal women (at the time of the CT scan, 47 fractured and 47 not fractured) to create a statistical anatomy atlas through principal component analysis, and up-sampled the atlas in order to obtain over 1000 synthetic patient models. We applied the biomechanical computed tomography pipeline to the resulting virtual cohort and compared its fracture risk distribution with that of the original physical cohort. While the distribution of femoral strength values in the non-fractured sub-group was nearly identical to that of the original physical cohort, that of the fractured sub-group was lower than in the physical cohort. Nonetheless, by using the classification threshold used for the original population, the synthetic population was still divided into two parts of approximatively equal number.