More Like this

1. Using point clouds to investigate the relationship between trabecular bone phenotype and behavior: An example utilizing the human calcaneus

   https://doi.org/10.1002/ajhb.23468  

   DeMars, Lily J. D. ; Stephens, Nicholas B. ; Saers, Jaap P. P. ; Gordon, Adam ; Stock, Jay T. ; Ryan, Timothy M. ( August 2020 , American Journal of Human Biology)

   The objective of this study is to demonstrate a new method for analyzing trabecular bone volume fraction and degree of anisotropy in three dimensions.

   We use a combination of automatic mesh registration, point‐cloud correspondence registration, andP‐value corrected univariate statistical tests to compare bone volume fraction and degree of anisotropy on a point by point basis across the entire calcaneus of two human groups with different subsistence strategies.

   We found that the patterns of high and low bone volume fraction and degree of anisotropy distribution between the Black Earth (hunter‐gatherers) and Norris Farms (mixed‐strategy agriculturalists) are very similar, but differ in magnitude. The hunter‐gatherers exhibit higher levels of bone volume fraction and less anisotropic trabecular bone organization. Additionally, patterns of bone volume fraction and degree of anisotropy in the calcaneus correspond well with biomechanical expectations of relative forces experienced during walking and running.

   We conclude that comparing site‐specific, localized differences in trabecular bone variables such as bone volume fraction and degree of anisotropy in three‐dimensions is a powerful analytical tool. This method makes it possible to determine where similarities and differences between groups are located within the whole skeletal element of interest. The visualization of multiple variables also provides a way for researchers to see how the trabecular bone variables interact within the morphology, and allows for a more nuanced understanding of how they relate to one another and the broader mechanical environment.

    

   more » « less
2. Trabecular bone functional adaptation and sexual dimorphism in the human foot

   https://doi.org/10.1002/ajpa.23732  

   Saers, Jaap P. P. ; Ryan, Timothy M. ; Stock, Jay T. ( November 2018 , American Journal of Physical Anthropology)

   Trabecular bone adapts to the strains placed upon the skeleton during life. Anthropological research has largely focused on linking variation in primate trabecular bone to locomotor mode, to provide a context for interpreting fossil morphology. However, intraspecific variation and its underlying mechanisms are still poorly understood. Trabecular bone is influenced by a variety of factors including body mass, age, diet, temperature, genetics, sex, and behavior. Before trabecular structure can be used to infer habitual behavior in the past, the effects of these factors need to be understood. In this article, we examine variation in trabecular structure in the human foot in four archaeological groups in relation to inferred levels of terrestrial mobility and sex.

   We use high‐resolution μCT scanning to examine variation in trabecular structure in the human calcaneus, talus, and first metatarsal in two relatively mobile and two relatively sedentary archaeological groups.

   The four population samples show similar patterns of trabecular variation throughout the foot, influenced by mechanical loading. Greater inferred terrestrial mobility is associated with greater bone volume fraction and thicker, more widely spaced, and less interconnected trabeculae. However, contrary to diaphyseal rigidity, only limited sexual dimorphism was found in trabecular structure.

   This work demonstrates that trabecular bone may serve as a useful proxy of habitual behavior in the fossil and archaeological record when other factors are carefully considered. However, the mechanisms underlying sexual dimorphism are not well understood. As such, inferring sex differences in habitual behavior is currently challenging.

    

   more » « less
3. The talar morphology of a hypochondroplasic dwarf: A case study from the Italian Late Antique period

   https://doi.org/10.1002/oa.3078  

   Sorrentino, Rita ; Carlson, Kristian J. ; Figus, Carla ; Pietrobelli, Annalisa ; Stephens, Nicholas B. ; DeMars, Lily J. D. ; Saers, Jaap P. P. ; Armando, Jessica ; Bettuzzi, Matteo ; Guarnieri, Tiziana ; et al ( December 2021 , International Journal of Osteoarchaeology)

   This project aims to test whether geometric morphometric (GM) and trabecular analyses may be useful tools in identifying talar characteristics related to hypochondroplasia. We quantified the external and internal talar morphology of a hypochondroplasic dwarf (T17) from Modena (northern Italy) dated to the sixth century AD. External talar morphology of T17 was compared with a broad sample of modern human tali (n = 159) using GM methods. Additionally, a subsample of these tali (n = 41) was used to investigate whole talar trabecular changes in T17. Our results show that GM and trabecular analyses identify a combination of traits linked to the dwarfing disorder of hypochondroplasia. These traits include decreased scaled talar dimensions compared with normal‐sized individuals, presence of an accessory antero‐lateral talar facet, high bone volume fraction, and high anisotropy values throughout the entire talus. In our case study, hypochondroplasia does not appear to substantially modify external talar morphology probably due to the fast growth of the talus. We suggest that small talar dimensions are associated with hypochondroplasia. An antero‐lateral talar facet may result from the talus and calcaneus coalition (i.e., talocalcaneal abnormal bridging) possibly related to an everted foot posture that was limited by overgrowth of the fibula. We suggest that high talar trabecular density and strut orientation provide insights into pathological development of the trabecular plates in T17. Finally, our study suggests that high talar trabecular density and strut orientation, and small talar dimensions, may be added as possible concomitant talar hallmarks for hypochondroplasia.

    

   more » « less
4. Incorporating tissue anisotropy and heterogeneity in finite element models of trabecular bone altered predicted local stress distributions

   https://doi.org/10.1007/s10237-017-0981-8  

   Hammond, Max A. ; Wallace, Joseph M. ; Allen, Matthew R. ; Siegmund, Thomas ( November 2017 , Biomechanics and Modeling in Mechanobiology)

   Trabecular bone is composed of organized mineralized collagen fibrils, which results in heterogeneous and anisotropic mechanical properties at the tissue level. Recently, biomechanical models computing stresses and strains in trabecular bone have indicated a significant effect of tissue heterogeneity on predicted stresses and strains. How-ever, the effect of the tissue-level mechanical anisotropy on the trabecular bone biomechanical response is unknown. Here, a computational method was established to automatically impose physiologically relevant orientation inherent in trabecular bone tissue on a trabecular bone microscale finite element model. Spatially varying tissue-level anisotropic elastic properties were then applied according to the bone mineral density and the local tissue orientation. The model was used to test the hypothesis that anisotropy in both homogeneous and heterogeneous models alters the predicted distribution of stress invariants. Linear elastic finite element computations were performed on a 3 mm cube model isolated from a microcomputed tomography scan of human trabecular bone from the distal femur. Hydrostatic stress and von Mises equivalent stress were recorded at every element, and the distributions of these values were analyzed. Anisotropy reduced the range of hydrostatic stress in both tension and compression more strongly than the associated increase in von Mises equivalent stress. The effect of anisotropy was independent of the spatial redistribution high compressive stresses due to tissue elastic heterogeneity. Tissue anisotropy and heterogeneity are likely important mechanisms to protect bone from failure and should be included for stress analyses in trabecular bone. 

   more » « less
5. Getting into Shape: Limb Bone Strength in Perinatal Lemur catta and Propithecus coquereli

   https://doi.org/10.1002/ar.24045  

   Young, Jesse_W ; Jankord, Kathryn ; Saunders, Marnie_M ; Smith, Timothy_D ( December 2018 , The Anatomical Record)

   Functional studies of skeletal anatomy are predicated on the fundamental assumption that form will follow function. For instance, previous studies have shown that the femora of specialized leaping primates are more robust than those of more generalized primate quadrupeds. Are such differences solely a plastic response to differential loading patterns during postnatal life, or might they also reflect more canalized developmental mechanisms present at birth? Here, we show that perinatalLemur catta, an arboreal/terrestrial quadruped, have less robust femora than perinatalPropithecus coquereli, a closely related species specialized for vertical clinging and leaping (a highly unusual locomotor mode in which the hindlimbs are used to launch the animal between vertical tree trunks). These results suggest that functional differences in long bone cross‐sectional dimensions are manifest at birth, belying simple interpretations of adult postcranial form as a direct record of loading patterns during postnatal life. Despite these significant differences in bone robusticity, we find that hindlimb bone mineralization, material properties, and measures of whole‐bone strength generally overlap in perinatalL. cattaandP. coquereli, indicating little differentiation in postcranial maturity at birth despite known differences in the pace of craniodental development between the species. In a broader perspective, our results likely reflect evolution acting during prenatal ontogeny. Even though primates are notable for relatively prolonged gestation and postnatal parental care, neonates are not buffered from selection, perhaps especially in the unpredictable and volatile environment of Madagascar. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:250–264, 2020. © 2018 American Association for Anatomy

    

   more » « less