Cross Section Contour of Femoral Shaft at the Mid Point: Variation in Modern Japanese and Jomon Populations

The configuration of the femur cross section is usually described in terms of the cross section index. However, the morphological information which is presented in this index is limited. A new technique is introduced here to analyze the variation of whole cross-sectional outlines statistically, in which morphological variability can be summarized in terms of fundamental variational patterns. This technique was applied to cross sections of the modern Japanese and Jomon (Japanese Neolithic) femora. It was revealed that the variation was represented by the combination of two underlying patterns: pilastering and asymmetry ("torsion"). Both fundamental patterns varied continuously in the studied populations, although the ranges differed by population. The results were shown visually to clarify that the range of variation was great in the modern Japanese, and that the degree of pilastering and sexual dimorphism were rather great in the Jomon femora. In the degree of torsion, the population difference was not found to be significant, despite that modern Japanese showed a wider range of variation.