A comparative study of foot morphology between Filipino and Japanese women, with reference to the significance of a deformity like hallux valgus as a normal variation.

In order to investigate the shape and size differences in feet caused by daily footwear, a comparative study was conducted on foot morphology in two populations. The data from six measurements in general physique and 18 measurements in the feet and their contours were obtained from 34 Filipino women in Isabela Province and 40 Japanese women in Tokyo. Despite the fact that the Tokyo women had larger physique than the Isabela women, there were no significant differences in foot size between two groups. Both relative size of foot for general physique and intragroup deviation of foot proportion were larger in the Isabela women than those in the Tokyo women. In comparing foot contour, many measurements relating particularly to foot proportion, represented by angles, showed significant differences between the two groups. In gross observation some of the Isabela women showed marked deformity of the grand toe to the lateral side, "like a hallux valgus' without any complaints. In principal-component analysis (PCA), CP1 was interpreted as size factor, CP2 was considered as position of foot axis, CP3 and CP4 were estimated as degree of angle between foot axis and ball axis. Means of individual score by PCA showed a completely inverse pattern between Isabela and Tokyo women. The differences in foot morphology recognized in these two groups were considered from the point of view of differences of daily footwear, which have not changed in the Philippines but have changed dramatically in Japan since World War II. We concluded that the deformity like a hallux valgus, frequently found in previous generations of Japanese who used to wear traditional footwear, geta and zori, must have been a healthy deformity, however, the pathological deformity hallux valgus is observed only in the Isabela women of today.