The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


A new method for the study of the biomechanical properties of human long bones and its application to ecogeographic and behavioral variation

TOM DAVIES and JAY T. STOCK.

Department of Archaeology and Anthropology, University of Cambridge

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This paper introduces a new method for the calculation of biomechanical properties from 3D laser scans. This method holds advantages over traditional periosteal moulding approaches, including: complete automation, virtual sectioning at multiple locations, and greater control over section orientation.

A sample of 295 humeri and femora were scanned using a NextEngine 3D laser scanner. Biomechanical properties were calculated from external contours using custom-built software. Comparison of the results with periosteal mould and radiographic based methods was used to test the method at mid-diaphyseal locations.

Regressions between methods show r2 values in excess of 0.99 and %SEE for total area of 1.6% and second moments of area between 3.3% and 10.1%. Despite strong correlations, the laser scanned sections tend to produce areas and second moments of area slightly lower than periosteal moulding, and higher than techniques including the endosteal boundary as would be predicted. The shape index Ix/Iy shows lower replicability confirming orientation issues in moulding techniques. The comparisons also highlight the importance of the periosteal contour in determining biomechanical properties.

Application of the method to variation across whole bones at 1% intervals (n=756) emphasizes varying roles for body shape variation and influences of activity in bone rigidity profiles. Proximal femoral shaft strengthening in wide-bodied hunter-gatherers and variable unilateral strengthening of the upper limb in certain groups is observed.

This study provides a new method for the calculation of biomechanical properties that allows investigation of whole bone variation in geometry and location-specific influences of activity across the skeleton.

This research was supported by funding from the Natural Environment Research Council, UK.

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