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


Form variation in the human knee joint: a geometric morphometric analysis of variation in the distal femur and proximal tibia in thirteen distinct populations

SALLY D. STEVENS and UNA STRAND VIDARSDOTTIR.

Department of Anthropology, Durham University, UK

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The high weight-bearing function on a relatively unstable joint would suggest that the knee (here comprising the distal femur and proximal tibia) is potentially subject to the greatest degree of localised stress and remodelling in the human skeleton. In addition, stress on this joint is highly idiosyncratic, implying that population specific differences are less likely to be found in this region of the skeleton than any other. Despite this supposition, this research, which uses geometric morphometric techniques and data from 387 right sided distal femora and 370 proximal tibiae from thirteen distinct worldwide populations has found population specific differences in shape in both bony elements of the joint at a high level of statistical significance. All Mahalanobis’s distances generated between samples are significant at p <0.0001, with cross-validation showing the mean percentage assigned to the correct groups at 94.53% (femur) and 89.75% (tibia). In contrast to cranial morphology, which is strongly influenced by genetic affiliation, morphological differences in knee joint form between groups largely arises through differences in the physical environment. Analyses producing such data can therefore provide additional information on environmental conditions prevailing in a population’s past history. Climatic variables such as ambient temperature, specifically cold winter temperature, and rainfall are shown to strongly influence morphology. Altitude, working environments and the use and type of footwear are also significant factors. Initial results also suggest that infection rates and compromised nutrition may also be influential.

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