Trabecular bone structural variation in the human postcranial skeleton

Abstract

Modern humans have relatively lightly built skeletons compared to other primates and earlier hominins which may predispose recent humans to bone‐related health risks such as osteopenia and osteoporosis. Although recent work suggests a relationship between higher activity/mobility and increased postcranial trabecular bone structure, the amount of variation in skeletal phenotype across modern humans and the role of declining activity/mobility and other factors in driving this variation remain unclear. The goal of this study is to characterize variation in trabecular bone structure in the human postcranial skeleton in relation to variation in subsistence strategy, mobility, and physical activity. The seventh cervical vertebral body, proximal humerus, proximal femur, and distal tibia from 60 young adult individuals from six populations were microCT scanned. These groups represented a behavioral/mobility gradient spanning from forager to post‐industrial populations. Bone volume fraction (BV/TV) and degree of anisotropy (DA) were quantified in the entire trabecular volume for each bone using Medtool 4.2. Results for each bone were mapped onto a 3D tetrahedral mesh and these meshes were registered using common morphological characters for visualization and analysis. For all groups BV/TV was highest in the cervical vertebra, followed by the proximal femur, distal tibia, and proximal humerus. DA was highest in the distal tibia, followed by the femur, humerus, and vertebra. The hunter‐gatherers had the highest BV/TV and lowest DA. Statistical comparisons of BV/TV and DA found significant differences among groups for the cervical vertebra (BV/TV) and distal tibia (BV/TV, DA). Comparisons of trabecular structure within each bone indicate broad similarities between groups with some unique patterns potentially reflective of behavioral and activity differences. The results demonstrate the potential for identifying functionally‐relevant trabecular bone patterns among skeletal elements, but indicate significant within and between individual variation that may obscure behavioral signals. The data may be useful in medical contexts looking to identify which postcranial elements are more diagnostic of or susceptible to osteopenia/osteoporosis, allowing for more targeted intervention.Support or Funding InformationFunding: NSF BCS‐1719187, NSF BCS‐1719140 RCUK/BBSRC grant BB/R01292X/1.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.