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Second metacarpal midshaft geometry in an historic cemetery sample
1Anthropology Program, University of Northern British Columbia, Prince George, Canada. lazenby@unbc.ca
American Journal of Physical Anthropology
|June 24, 1998
Summary
Direct measurements of second metacarpal bone cross-sections reveal age, sex, and side variations. Bone mass declines with age, and males have larger bones, but the diaphysis is not circular, especially in females.
Area of Science:
- Anthropology
- Biomechanics
- Skeletal Biology
Background:
- Bone mass studies at the second metacarpal midshaft inform skeletal growth and aging.
- Noninvasive techniques, particularly radiogrammetry, are commonly used for bone mass assessment.
Purpose of the Study:
- To analyze age, sex, and side variations in the size and shape of the second metacarpal midshaft.
- To investigate the cross-sectional geometry of the second metacarpal and compare it to assumptions of circularity.
Main Methods:
- Direct measurement of cross-sections from a homogeneous skeletal sample (n=356).
- Correlation analysis and three-way ANOVA of size-adjusted data.
- Assessment of cross-sectional geometry to determine diaphysis shape and bone strength axes.
Main Results:
- Males exhibit absolutely larger bones than females, with significant age-related bone mass decline in males.
- The right side is generally larger than the left, but 25% of left metacarpals were larger.
- The second metacarpal midshaft is noncircular, with females displaying a more cylindrical diaphysis than males.
Conclusions:
- Direct measurements confirm the noncircularity of the second metacarpal midshaft, challenging previous assumptions.
- Observed variations in bone mass and shape suggest adaptation to biomechanical forces, particularly bending moments.
- Further research into the functional anatomy of the metacarpal diaphysis is needed to fully understand these findings.