Methodological considerations for analyzing trabecular architecture: an example from the primate hand

Abstract

Micro-computed tomographic analyses of trabecular bone architecture have been used to clarify the link between positional behavior and skeletal anatomy in primates. However, there are methodological decisions associated with quantifying and comparing trabecular anatomy across taxa that vary greatly in body size and morphology that can affect characterizations of trabecular architecture, such as choice of the volume of interest (VOI) size and location. The potential effects of these decisions may be amplified in small, irregular-shaped bones of the hands and feet that have more complex external morphology and more heterogeneous trabecular structure compared to, for example, the spherical epiphysis of the femoral head. In this study we investigate the effects of changes in VOI size and location on standard trabecular parameters in two bones of the hand, the capitate and third metacarpal, in a diverse sample of nonhuman primates that vary greatly in morphology, body mass and positional behavior. Results demonstrate that changes in VOI location and, to a lesser extent, changes in VOI size had a dramatic affect on many trabecular parameters, especially trabecular connectivity and structure (rods vs. plates), degree of anisotropy, and the primary orientation of the trabeculae. Although previous research has shown that some trabecular parameters are susceptible to slight variations in methodology (e.g. VOI location, scan resolution), this study provides a quantification of these effects in hand bones of a diverse sample of primates. An a priori understanding of the inherent biases created by the choice of VOI size and particularly location is critical to robust trabecular analysis and functional interpretation, especially in small bones with complex arthroses.

Evidence in hand: recent discoveries and the early evolution of human manual manipulation

“…Finally, greater access to three-dimensional scanning techniques, including surface scanning [34][35][36][53][54][55][56][57][58][59][60][61]98,99] and microtomography [109,110], has allowed for more comprehensive functional analyses of both the external and internal morphology of hand bones. In particular, analyses of the internal trabecular morphology of hand bones has provided new insights into how early hominins may have actually, rather than potentially, used their hands [110].…”

Tool making, hand morphology and fossil hominins

“…Caveats to measurement and interpretation of this structure should be considered [60], and it is hoped that further studies will lead to possible new predictors of behaviours.…”

Trabecular architecture in the humeral metaphyses of non‐avian reptiles (Crocodylia, Squamata and Testudines): Lifestyle, allometry and phylogeny

“…Thanks to the development of X‐ray computed microtomography, 3D trabecular architecture could be extensively studied in birds (e.g., Bishop et al, ; Doube, Kłosowski, Wiktorowicz‐Conroy, Hutchinson, & Shefelbine, ; Fajardo, Hernandez, & O'Connor, ; Pontzer et al, ) and mammals (e.g., many orders [Doube et al, ], bovids [Mittra, Rubin, & Qin, , Sode, Burghardt, Nissenson, & Majumdar, ], lagomorphs [Marchand, Chen, Buschmann, & Hoemann, , van der Meulen et al, ], primates [Barak, Lieberman, Raichlen, et al, , Cunningham & Black, , Kivell, Skinner, Lazenby, & Hublin, , Lazenby, Skinner, Kivell, & Hublin, , Sode et al, ], rodents [Carlson, Lublinsky, & Judex, , Lambers et al, , Sode et al, ], sciuromorphs [Mielke et al, ], suids [Ben‐Zvi, Reznikov, Shahar, & Weiner, ], and xenarthrans [Amson et al, ]). In comparison, 3D trabecular architecture of nonavian reptiles has received little attention.…”