Cortical and trabecular bone density distribution in primate and felid limb epiphyses

Abstract

Studies show that cortical and trabecular bone are responsive to mechanical loading, albeit in different ways. Increased loading results in an increase in trabecular bone density in epiphyses, whereas articular cortical bone is conserved to maintain joint congruity. However, the co‐distribution of articular cortical and trabecular bone density in joints has not been reported within a mechanical loading context, and in reference to locomotor behavior. This study analyzes cortical and trabecular bone density co‐distribution based on habitual loading in multiple limb elements across taxa with different locomotor behaviors (bipeds, terrestrial quadrupeds and arboreal quadrupeds). We predict that joints subjected to greater loading during locomotion will have an increased ratio of trabecular bone density to cortical bone than those that experience reduced loading. Specifically, we predict that non‐primate quadrupeds known to experience greater substrate reaction forces on the forelimb than hindlimb will exhibit greater trabecular to cortical bone density ratio in the forelimb epiphyses than the primate quadrupeds. We test this prediction using peripheral quantitative computed tomography (pQCT) measuring trabecular and cortical bone density in primates and felids. Results from one‐way ANOVA with Tukey post‐hoc corrections show that the femoral head in all locomotor groups studied display the least ratio between trabecular and cortical bone density in comparison to other limb elements. Additionally, other elements did not follow predicted patterns of bone density distribution based on locomotor behavior. Instead, they vary according to phylogeny. The results indicate that the femoral head, a relatively large epiphyseal element, displays greater density ‐ both cortical and trabecular ‐ regardless of locomotor repertoire. This suggests there are potentially non‐loading factors influencing observed bone distribution patterns. Furthermore, this study correlates bone density, fracture susceptibility, and injury risk, which have significant clinical applications.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.