Can the sedentary behavior of basketball and volleyball players impact bone mass and bone geometry?

The aim of the study was to evaluate the relationship between sedentary behavior, bone mass, and bone geometry among young male basketball and volleyball players. This cross-sectional study included 55 adolescent basketball ( n = 21) and volleyball ( n = 34) players (14–17 years). Body composition (body mass index, fat mass, and lean mass) was measured by dual-energy X-ray absorptiometry, comprising bone mineral density, bone mineral content at the lumbar spine, and femoral neck. Bone geometry considered the femur strength index, section modulus, cross-sectional moment of inertia, and cross-sectional area. Dietary intake was obtained through a semiquantitative questionnaire, and the sedentary behavior, by the Adolescent Sedentary Activity Questionnaire. Linear regression models, fitted by Bayesian methods, explored the variation of the variables by sport. Body composition and bone mass values were high for both sports, but there was no variation for body composition. Adjusting for age, there was no association of sedentary behavior on bone parameters. For femoral strength index, age had a moderate to large association with all bone indicators. Lastly, there was influence of sport (level-2 unit) on the estimates of the association between sedentary behavior and age with bone indicators, as uncertainty estimates for group-level effects were high. There is no association between sedentary behavior and bone parameters, showing that accumulated training loads (15+ h/wk) among young basketball and volleyball players are critical; producing a positive stimulus on bone parameters development.

Enthesis strength, toughness and stiffness: an image-based model comparing tendon insertions with varying bony attachment geometries

Tendons of the body differ dramatically in their function, mechanics and range of motion, but all connect to bone via an enthesis. Effective force transfer at the enthesis enables joint stability and mobility, with strength and stiffness arising from a fibrous architecture. However, how enthesis toughness arises across tendons with diverse loading orientations remains unclear. To study this, we performed simultaneous imaging of the bone and tendon in entheses that represent the range of tendon-to-bone insertions and extended a mathematical model to account for variations in insertion and bone geometry. We tested the hypothesis that toughness, across a range of tendon entheses, could be explained by differences observed in interactions between fibre architecture and bone architecture. In the model, toughness arose from fibre reorientation, recruitment and rupture, mediated by interactions between fibres at the enthesis and the bony ridge abutting it. When applied to tendons sometimes characterized as either energy-storing or positional, the model predicted that entheses of the former prioritize toughness over strength, while those of the latter prioritize consistent stiffness across loading directions. Results provide insight into techniques for surgical repair of tendon-to-bone attachments, and more broadly into mechanisms for the attachment of highly dissimilar materials.

Morphological Variation In Paediatric Lower Limb Bones

Available methods for generating paediatric musculoskeletal geometry are to scale generic adult geometry, which is widely accessible but can be inaccurate, or to obtain geometry from medical imaging, which is accurate but time-consuming and costly. A population-based shape model is required to generate accurate and accessible musculoskeletal geometry in a paediatric population. The pelvis, femur, and tibia/fibula were segmented from 333 CT scans of children aged 4-18 years. Bone morphology variation was captured using principal component analysis (PCA). Subsequently, a shape model was developed to predict bone geometry from demographic and linear bone measurements and validated using a leave one out analysis. The shape model was compared to linear scaling of adult and paediatric bone geometry. The PCA captured growth-related changes in bone geometry. The shape model predicted bone geometry with root mean squared error (RMSE) of 2.91±0.99mm in the pelvis, 2.01±0.62mm in the femur, and 1.85±0.54mm in the tibia/fibula. Linear scaling of an adult mesh produced RMSE of 4.79±1.39mm in the pelvis, 4.38±0.72mm in the femur, and 4.39±0.86mm in the tibia/fibula. We have developed a method for capturing and predicting lower limb bone shape variation in a paediatric population more accurately than linear scaling without using medical imaging.

Statistical-Shape Prediction of Lower Limb Kinematics During Cycling, Squatting, Lunging, and Stepping—Are Bone Geometry Predictors Helpful?

Purpose: Statistical shape methods have proven to be useful tools in providing statistical predications of several clinical and biomechanical features as to analyze and describe the possible link with them. In the present study, we aimed to explore and quantify the relationship between biometric features derived from imaging data and model-derived kinematics.Methods: Fifty-seven healthy males were gathered under strict exclusion criteria to ensure a sample representative of normal physiological conditions. MRI-based bone geometry was established and subject-specific musculoskeletal simulations in the Anybody Modeling System enabled us to derive personalized kinematics. Kinematic and shape findings were parameterized using principal component analysis. Partial least squares regression and canonical correlation analysis were then performed with the goal of predicting motion and exploring the possible association, respectively, with the given bone geometry. The relationship of hip flexion, abduction, and rotation, knee flexion, and ankle flexion with a subset of biometric features (age, length, and weight) was also investigated.Results: In the statistical kinematic models, mean accuracy errors ranged from 1.60° (race cycling) up to 3.10° (lunge). When imposing averaged kinematic waveforms, the reconstruction errors varied between 4.59° (step up) and 6.61° (lunge). A weak, yet clinical irrelevant, correlation between the modes describing bone geometry and kinematics was observed. Partial least square regression led to a minimal error reduction up to 0.42° compared to imposing gender-specific reference curves. The relationship between motion and the subject characteristics was even less pronounced with an error reduction up to 0.21°.Conclusion: The contribution of bone shape to model-derived joint kinematics appears to be relatively small and lack in clinical relevance.

Peak and Per-Step Tibial Bone Stress During Walking and Running in Female and Male Recreational Runners

Background: Athletes, especially female athletes, experience high rates of tibial bone stress injuries (BSIs). Knowledge of tibial loads during walking and running is needed to understand injury mechanisms and design safe running progression programs. Purpose: To examine tibial loads as a function of gait speed in male and female runners. Study Design: Controlled laboratory study. Methods: Kinematic and kinetic data were collected on 40 recreational runners (20 female, 20 male) during 4 instrumented gait speed conditions on a treadmill (walk, preferred run, slow run, fast run). Musculoskeletal modeling, using participant-specific magnetic resonance imaging and motion data, was used to estimate tibial stress. Peak tibial stress and stress-time impulse were analyzed using 2-factor multivariate analyses of variance (speed*sex) and post hoc comparisons (α = .05). Bone geometry and tibial forces and moments were examined. Results: Peak compression was influenced by speed ( P < .001); increasing speed generally increased tibial compression in both sexes. Women displayed greater increases in peak tension ( P = .001) and shear ( P < .001) than men when transitioning from walking to running. Further, women displayed greater peak tibial stress overall ( P < .001). Compressive and tensile stress-time impulse varied by speed ( P < .001) and sex ( P = .006); impulse was lower during running than walking and greater in women. A shear stress-time impulse interaction ( P < .001) indicated that women displayed greater impulse relative to men when changing from a walk to a run. Compared with men, women displayed smaller tibiae ( P < .001) and disproportionately lower tibial forces ( P≤ .001-.035). Conclusion: Peak tibial stress increased with gait speed, with a 2-fold increase in running relative to walking. Women displayed greater tibial stress than men and greater increases in stress when shifting from walking to running. Sex differences appear to be the result of smaller bone geometry in women and tibial forces that were not proportionately lower, given the womens’ smaller stature and lower mass relative to men. Clinical Relevance: These results may inform interventions to regulate running-related training loads and highlight a need to increase bone strength in women. Lower relative bone strength in women may contribute to a sex bias in tibial BSIs, and female runners may benefit from a slower progression when initiating a running program.

Modifying the Gut Microbiome Through Diet or Antibiotics Alters Bone Phenotypes in Older Mice

Objectives Gut microbiota have been shown to influence bone quality and quantity, both risk determinants for osteoporosis. Previous research in young mice showed oral antibiotic treatment during rapid bone gain impaired bone tissue quality. We sought to determine if modifying the gut microbiome of aged mice through diet or antibiotic treatment affects bone geometry and/or strength. Methods A high (HG) or low glycemic (LG) diet was fed in equal amounts to 12-mo. male mice. The diets differed only by starch composition, which was 100% rapidly digested amylopectin in the HG diet or 30% amylopectin/70% amylose in the LG diet. A third group received the LG diet containing antibiotics (ampicillin and neomycin; LGAbx). Feces were collected at baseline and after 10 months of treatment and 16s rRNA sequencing was performed followed by ecological diversity and differential abundance analysis. Femora were harvested after 12 months of treatment for analysis of bone geometry and strength via mechanical testing and imaging. Results Antibiotic treatment reduced alpha diversity, including an average 92% reduction in observed OTUs from baseline compared with 30% reduction in the other groups. Both diet and antibiotic treatment significantly altered taxonomic composition, including an expansion of Proteobacteria in response to antibiotics. Whole bone strength is determined by a combination of the section modulus (the measure of geometry most closely related to bending strength) and the mechanical properties of the bone tissue itself. In HG-fed mice the section modulus was greater than that of the other groups and the bone showed a correspondingly greater strength. However, in LGAbx-fed mice the whole bone strength was 22% lower than bones with similar section modulus in the LG and HG-fed groups, indicating impaired bone tissue material properties. Conclusions Altering diet resulted in significant changes to bone geometry and strength, while changes in the gut microbiota associated with antibiotic treatment resulted in a reduction to bone strength which could not be explained by bone geometry. Our study indicates that dietary or antibiotics treatments applied to mice later in life can alter bone properties, which suggests that interventions to improve bone strength may be effective in older adults. Funding Sources NIH/NIAMS, BrightFocus Foundation, Stanley N. Gershoff Scholarship.