A three‐dimensional microcomputed tomographic study of site‐specific variation in trabecular microarchitecture in the human second metacarpal

Abstract

Variation in trabecular microarchitecture is widely accepted as being regulated by both functional (mechanical loading) and genetic parameters, although the relative influence of each is unclear. Studies reporting intersite differences in trabecular morphology (volume, number and structure) reveal a complex interaction at the gene-environment interface. We report inter-and intra-site variation in trabecular anatomy using a novel model of contralateral (left vs right) and ipsilateral (head vs base) comparisons for the human second metacarpal in a sample of n = 29 historically known 19th century EuroCanadians. Measures of bone volume fraction, structure model index, connectivity, trabecular number, spacing and thickness as well as degree of anisotropy were obtained from 5-mm volumes of interest using three-dimensional microcomputed tomography. We hypothesized that: (i) the more diverse loading environment of metacarpal heads should produce a more robust trabecular architecture than corresponding bases within sides and (ii) the ipsilateral differences between epiphyses will be larger on the right side than on the left side, as a function of handedness. Analysis of covariance (Side × Epiphysis) with Age as covariate revealed a clear dichotomy between labile and constrained architectures within and among anatomical sites. The predicted variation in loading was accommodated by changes in trabecular volume, whereas trabecular structure did not vary significantly by side or by epiphysis within sides. Age was a significant covariate only for females. We conclude that environmental and genetic regulation of bone adaptation may act through distinct pathways and local anatomies to ensure an integrated lattice of sufficient mass to meet normal functional demands.

Does skeletal anatomy reflect adaptation to locomotor patterns? cortical and trabecular architecture in human and nonhuman anthropoids

“…This variability is likely to have influenced the results of the current study. Future investigations of this type may consider assessing more constrained joints in the skeleton (Carlson et al, 2008a;Lazenby et al, 2008;Griffin et al, 2010;. The hind limb dominance of most anthropoids undoubtedly influences the distribution of cortical bone robusticity and trabecular bone architectural properties.…”

“…The analysis of both sub-articular trabeculae and diaphyseal cortical bone is a relatively new approach (see Carlson and Judex, 2007;Carlson et al, 2008a;Lazenby et al, 2008) that allows for direct comparisons of morphological variation in two types of osseous tissue, within the same skeletal element. The integrated consideration of diaphyseal and trabecular bone properties is a perspective that attempts to move away from the reductionism that often occurs with trabecular bone analyses in the comparative literature.…”

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

“…Trabecular connectivity and structure are calculated in a similar way and are highly correlated (Lazenby et al. 2008a), thus it is not unexpected that they are equally affected by changes to the VOI.…”

“…2007; Scherf & Hublin, 2007; Scherf, 2008; Scherf et al. 2009) and manipulative behaviors (Lazenby et al. 2008a,b), providing novel insight into the functional interpretation of both extant and fossil primate morphology (Ryan & Ketcham, 2002b; Scherf, 2008).…”

Laterality and grip strength influence hand bone micro‐architecture in modern humans, an HRpQCT study

“…Our findings highlight that a level of activity or strength might be determined as a threshold to stimulate aptation to environment. Lazenby et al (2008a) suggest that volumetric variables such as BV/TV and Tb.N are sensitive to mechanical regulation and handedness. Further, they found that the influence of age is felt more on the left rather than the right metacarpal given the human propensity for right-handedness.…”