1Department of Anthropology, Pennsylvania State University, 2Eberly College of Science, Pennsylvania State University, 3School of Anthropology, University of Arizona, 4Department of Anthropology, Ohio State University, 5Center for Quantitative X-Ray Imaging, Pennsylvania State University
March 27, 2015 , Archview Ballroom
The femoral bicondylar angle develops during ontogeny in response to changes in loading associated with the onset and maturation of bipedal walking. The magnitude and orientation of loads at the knee joint change significantly during development as the bicondylar angle increases and then stabilizes. The goal of this study is to assess trabecular bone structural changes in the distal femur in relation to the developing bicondylar angle with the expectation that bone structure will reflect a shift in load magnitude and orientation at the knee during ontogeny. Three-dimensional trabecular bone architecture in the distal femur was quantified from microCT data in 57 individuals from the Norris Farms #36 archaeological skeletal collection. Bicondylar angle was quantified by measuring the angle between the long axis of the bone and the distal femoral metaphyseal margin. Individuals ranged in age from neonate to adult. We found no significant differences in bone volume fraction (BV/TV), trabecular spacing, or connectivity between the medial and lateral metaphyses in any age group. Trabecular bone in the medial metaphysis was significantly thicker and more isotropic than in the lateral side across all age groups. The degree of anisotropy (DA) in the medial condyle was the only variable significantly correlated with bicondylar angle. These results suggest that trabecular bone structure in the distal femoral metaphysis does not reflect changes in load magnitude (BV/TV), but appears to track changes in load orientation (DA) in the medial condyle during skeletal development, and the acquisition and maturation of bipedal gait.
Grant Support: NSF BCS 1028904 (TMR), 1028793 (JHG), and 1028799 (DAR).