Geometry Of Long Bones Research Articles

Endostructural and periosteal growth of the human humerus.

The growth and development of long bones are of considerable interests in the fields of comparative anatomy and palaeoanthropology, as evolutionary changes and adaptations to specific physical activity patterns are expected to be revealed during bone ontogeny. Traditionally, the cross-sectional geometry of long bones has been examined at discrete locations usually placed at set intervals or fixed percentage distances along the midline axis of the bone shaft. More recently, the technique of morphometric mapping has enabled the continuous analysis of shape variation along the shaft. Here we extend this technique to the full sequence of late fetal and postnatal development of the humeral shaft in a modern human population sample, with the aim of establishing the shape changes during growth and their relationship with the development of the arm musculature and activity patterns. A sample of modern human humeri from individuals of age ranging from 24 weeks in utero to 18 years was imaged using microtomography at multiple resolutions and custom Matlab scripts. Standard biomechanical properties, cortical thickness, surface curvature, and pseudo-landmarks were extracted along radial vectors spaced at intervals of 1° at each 0.5% longitudinal increment measured along the shaft axis. Heat maps were also generated for cortical thickness and surface curvature. The results demonstrate that a whole bone approach to analysis of cross-sectional geometry is more desirable where possible, as there is a continuous pattern of variation along the shaft. It is also possible to discriminate very young individuals and adolescents from other groups by relative cortical thickness, and also by periosteal surface curvature.

The daily grind: Sex- and age-related activity patterns inferred from cross-sectional geometry of long bones in a pre-Columbian muisca population from Tibanica, Colombia.

Daily activities involve biomechanical strains acting on skeletal structures. This study identifies differences in activity patterns between males and females, and between young, middle, and older aged individuals within an excavated Muisca skeletal sample from the Eastern Andes region of Northern South America. The Tibanica archaeological site (AD 1000-1400) is located at 2600 masl on the Sabana de Bogotá, Colombia. Cross-sectional geometric analysis of femurs from 63 individuals and paired-humerii from 33 individuals was used to examine bone size (TA), strength (J) and diaphyseal shape (Imax /Imin , Ix /Iy ). The findings indicate both age- and sex-related differences in activity patterns. An emphasis on upper body strength and robusticity was observed in the females, while males performed more strenuous work using their lower bodies, suggesting gender-based differences in labor. Men showed significant asymmetry in their humerii, with most showing right-hand dominance for upper body activities, while females showed high levels of humeral symmetry indicating similar levels of biomechanical stress for both arms. Female femoral diaphyseal shape changes with age, suggesting more mobility in youth and decreased mobility in middle and older ages. These results suggest that daily life may have been structured through patterns of routine labor that united and divided particular age and sex groups. Cross-sectional geometry data indicate women likely spent significant time and energy preparing food, especially grinding maize or other foods, while men may have done more long-distance walking potentially to work in agricultural fields or procure other resources.

Análisis comparativo de la geometría de la sección transversal de tibias de restos humanos de Patagonia austral y centro-norte de Mendoza

El análisis de la geometría transversal de los huesos largos es un indicador de las fuerzas mecánicas a las que están sometidas las estructuras óseas, que refleja la actividad física, la salud nutricional y la variabilidad genética de los individuos. Aunque algunos análisis fueron realizados previamente en restos de individuos de la Patagonia austral, las conclusiones obtenidas parecen contradictorias respecto de la posible relación entre la morfología ósea de los huesos largos y la actividad física. El objetivo de este trabajo es profundizar en forma comparativa el análisis de la geometría de la sección transversal de las tibias de individuos de la Patagonia austral y el Centro-Norte de Mendoza, explorando la posible asociación entre el tipo de práctica económica realizada y el desarrollo de las estructuras óseas de los miembros inferiores. Los resultados muestran que no existen diferencias significativas entre la robusticidad de los miembros inferiores de poblaciones de la Patagonia y del Centro-Norte de Mendoza. Sin embargo, al analizar los resultados de acuerdo con la dieta, los individuos con dietas marítimas en la Patagonia austral presentaron tibias más robustas que aquellos con dietas terrestres. En los individuos del Centro-Norte de Mendoza, los restos de individuos con dietas asociadas al consumo de maíz mostraron menor robusticidad en relación con otros individuos de esa región. Finalmente, sólo un caso de la Patagonia austral mostró resultados que podrían indicar que fue afectado por un trastorno metabólico de la salud.

A technique for developing CAD geometry of long bones using clinical CT data

Computed tomography scans are a valuable tool for developing computational models of bones. The objective of this study is to present a method to generate CAD representations of long bones from clinically based CT scans. A secondary aim is to apply the method to six long bones from a sample of three individuals. Periosteal and endosteal bone surfaces were segmented and used to calculate the characteristic cortical thickness, Tc, at 1 mm increments along the bone axis. In the epiphyses where the value of Tc fell below the scanner threshold, the endosteal bone layer was replaced using literature values projected inward from the periosteal surface. On average, 74.7 ± 7.4% of the bone geometry was above the scanner cut-off and was therefore derived from the CT scan data. The thickness measurement was also compared to experimental measurements of cadaveric bone and was found to predict Tc with an error of 3.1%. This method presents a possible solution for the characterization of characteristic thickness along the length of the bone and may also aid in the development of orthopedic implant design and subject specific finite element models.

Identifying donkey domestication through changes in cross-sectional geometry of long bones

The initial phases of donkey domestication are difficult to identify in the archaeological record due to late and inconsistent changes in morphology and body size in the earliest domestics. Use of donkeys for load carrying and the management of captive herds resulted in a distinctive behavioral shift away from the free-ranging speed and mobility characteristic of wild asses toward slower, more steady pacing. Given the ability of bone to adapt to its mechanical environment, bone remodeling in the limbs of wild asses and donkeys are evaluated using cross-sectional geometry to determine whether weight bearing or locomotor differences between the wild and domestic forms may be used to recognize early domestication. Cross-sectional data were collected on the humeri, radii, metacarpals and metatarsals of eight wild ass and six donkey skeletons. Wild ass forelimbs have greater overall strength and more cylindrical humeral diaphyses, indicating better resistance to a varied locomotor repertoire. These results demonstrate that analyses of shaft geometry can provide information on changes in locomotor behavior during domestication. Our finding that shifts in gait had greater effects on the morphology of early domestic donkeys than did load-carrying places a new emphasis on understanding selection for gait changes in domestication dynamics.

Humeral Cross‐Sectional Shape in Suspensory Primates and Sloths

Studies on the cross‐sectional geometry of long bones in African apes have documented that shape ratios derived from second moments of area about principle axes (e.g., Imax/Imin) are often correlated with habitual locomotor behaviors. For example, humeral cross‐sections tend to appear more circular in more arboreal and forelimb suspensory chimpanzees compared with terrestrial quadrupedal gorillas. These data support the hypothesis that cross‐sections that are more circular in shape are adapted for multidirectional loading regimes and bending moments encountered when using acrobatic locomotor behaviors. Whether a more circular humerus reflects greater use of forelimb suspension in other primates and nonprimate mammals is unknown. In this study, cross‐sections at or near midshaft of the humerus were obtained from anthropoid primates that differ in their use of forelimb suspension, as well as from two genera of suspensory sloths. Imax/Imin ratios were compared within and between groups, and correlations were made with behavioral data. In broad comparisons, observed differences in morphology follow predicted patterns. Humeri of suspensory sloths are circular. Humeri of the more suspensory hominoids tend to be more circular than those of quadrupedal taxa. Humeri of the suspensory atelines are similar to hominoids, while those of Cebus are more like nonsuspensory cercopithecoids. There is, however, considerable overlap between taxa and within finer comparisons variation between species are not in the predicted direction. Thus, although Imax/Imin ratios of the humerus are informative for characterizing generalized locomotor modes (i.e., forelimb suspensory vs. quadrupedal), additional structural information is needed for more fine‐grained assessments of locomotion. Anat Rec, 296:545–556, 2013. © 2013 Wiley Periodicals, Inc.

Humeral Cross‐Sectional Shape in Suspensory Primates and Sloths

Studies on the cross-sectional geometry of long bones in African apes have documented that shape ratios derived from second moments of area about principle axes (e.g., Imax /Imin ) are often correlated with habitual locomotor behaviors. For example, humeral cross-sections tend to appear more circular in more arboreal and forelimb suspensory chimpanzees compared with terrestrial quadrupedal gorillas. These data support the hypothesis that cross-sections that are more circular in shape are adapted for multidirectional loading regimes and bending moments encountered when using acrobatic locomotor behaviors. Whether a more circular humerus reflects greater use of forelimb suspension in other primates and nonprimate mammals is unknown. In this study, cross-sections at or near midshaft of the humerus were obtained from anthropoid primates that differ in their use of forelimb suspension, as well as from two genera of suspensory sloths. Imax /Imin ratios were compared within and between groups, and correlations were made with behavioral data. In broad comparisons, observed differences in morphology follow predicted patterns. Humeri of suspensory sloths are circular. Humeri of the more suspensory hominoids tend to be more circular than those of quadrupedal taxa. Humeri of the suspensory atelines are similar to hominoids, while those of Cebus are more like nonsuspensory cercopithecoids. There is, however, considerable overlap between taxa and within finer comparisons variation between species are not in the predicted direction. Thus, although Imax /Imin ratios of the humerus are informative for characterizing generalized locomotor modes (i.e., forelimb suspensory vs. quadrupedal), additional structural information is needed for more fine-grained assessments of locomotion.

32 How Ultrasound Bidirectional Axial Transmission Reflects Geometry of Long Bones?

Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days.

Ultrasonically determined thickness of long cortical bones: Three-dimensional simulations of in vitro experiments

It was reported in a previous study that simulated guided wave axial transmission velocities on two-dimensional (2D) numerically reproduced geometry of long bones predicted moderately real in vitro ultrasound data on the same bone samples. It was also shown that fitting of ultrasound velocity with simple analytical model yielded a precise estimate (UTh) for true cortical bone thickness. This current study expands the 2D bone model into three dimensions (3D). To this end, wave velocities and UTh were determined from experiments and from time-domain finite-difference simulations of wave propagation, both performed on a collection of 10 human radii (29 measurement sites). A 3D numerical bone model was developed with tuneable fixed material properties and individualized geometry based on X-ray computed tomography reconstructions of real bones. Simulated UTh data were in good accordance (root-mean-square error was 0.40 mm; r(2)=0.79, p<0.001) with true cortical thickness, and hence the measured phase velocity can be well estimated by using a simple analytical inversion model also in 3D. Prediction of in vitro data was improved significantly (by 10% units) and the upgraded bone model thus explained most of the variability (up to 95% when sites were carefully matched) observed in in vitro ultrasound data.

Cortical bone distribution in the femoral neck of strepsirhine primates

The thickness of the inferior and superior cortices of the femoral neck was measured on X-rays of 181 strepsirhine primate femora representing 24 species. Neck length, neck depth and neck-shaft angle were also measured. The strength of the femoral neck in frontal bending was estimated by modeling the neck as a hollow cylinder, with neck depth as the outer diameter and cortical thickness representing the superior and inferior shell dimensions. Results indicate that the inferior cortex is always thicker than the superior cortex. The ratio of superior to inferior cortical thickness is highly variable but distinguishes two of the three locomotor groups in the sample. Vertical clingers and leapers have higher ratios (i.e., a more even distribution of cortical bone) than quadrupeds. The slow climbers tend to have the lowest ratios, although they do not differ significantly from the leapers and quadrupeds. These results do not confirm prior theoretical expectations and reported data for anthropoid primates that link greater asymmetry of the cortical shell to more stereotypical hip excursions. The ratio of superior to inferior cortical thickness is unrelated to body mass, femoral neck length, and neck-shaft angle, calling into question whether the short neck of strepsirhine primates acts as a cantilever beam in bending. On the other hand, the estimated section moduli are highly correlated with body mass and neck length, a correlation that is driven primarily by body mass. In conclusion, we believe that an alternative interpretation to the cantilever beam model is needed to explain the asymmetry in bone distribution in the femoral neck, at least in strepsirhine primates (e.g., a thicker inferior cortex is required to reinforce the strongly curved inferior surface). As in prior studies of cross-sectional geometry of long bones, we found slightly positive allometry of cortical dimensions with body mass.

Changes in Activities with the Shift to Agriculture in the Southeastern United States

Changes in Activities with the Shift to Agriculture in the Southeastern United States