The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


Asymmetry of the endosteal lamellar pocket and cross-sectional properties in the human second metacarpal

EMELINE RAGUIN1, MARGARET A. STREETER2, RICHARD LAZENBY3 and MICHELLE S.M. DRAPEAU1.

1Department of Anthropology, Université de Montréal, 2Department of Anthropology, Boise State University, 3Department of Anthropology, University of Northern British Columbia

March 27, 2015 , Archview Ballroom Add to calendar

Previous studies have hypothesized that the endosteal lamellar pocket (ELP), primary circumferential lamellar bone remaining from bone modeling, could be a functional adaptation to mechanical load changes during growth. Accordingly, we would expect ELP to be larger on bones that incurred larger loads. We test this hypothesis by comparing the asymmetric expression of the ELP to the asymmetry of cross-sectional properties in the human upper limb. More specifically, this study tests whether right-left asymmetry of ELP area is correlated with asymmetry in bending rigidity measurements (Ix, Iy, Imax and Imin), polar moment of area (J) and total and cortical areas (TA, CA). Our sample consists of right and left second metacarpals from two populations: Eurocanadian settlers (n=22), from a cemetery active between 1821 and 1874, and Sadlermiut Inuit from the Central Canadian Arctic proto-historic period (n=10). In order to evaluate the asymmetric relationship, we calculated the % right-left differences for each variable and tested for correlations between ELP and macroscopic measurements.

No correlation was found between ELP area and cross-sectional properties. However, when populations were analyzed separately, the Eurocanadians sample showed a significant (p<0.05) correlation between asymmetries of ELP and CA (R=0.48), and Imin (R= 0.54), but when Bonferroni’s correction was applied to control for the number of tests performed, no results were significant (p<0.007). This preliminary study does not support the hypothesis that ELP is principally deposited to meet changing biomechanical loads in the second metacarpals, but rather, suggests that ELP is the result of a natural growth process.

This research was funded in part by the FQRSC and CFI (to MSMD) and by NSERC and UNBC Seed grant (to RL).