Morphological Variation in Talar Joint Facets of the Human Calcaneus I. :

Basic Morphological and Statistical Analyses

Abstract

The talar joint facets of the calcaneus were classified into 5 types according to their configuration: single facet type, continuous type, demarcated type, separate type, and no anterior facet type. Side association, side difference, sex difference, and age change in the incidence of occurrence of the 5 types, and association between the morphological classifications of the joint surfaces of the calcaneus and talus were investigated using a dissecting room Japanese skeletal series of known sex and age. Measurements were also taken for the length and depth of the anterior and middle talar facets of the calcaneus. The results showed that 1) Each individual type of talar joint facet was highly associated by side; 2) No side difference in trait incidence was found; 3) The sex difference in trait incidence was significant at the 5% level; 4) No age change in trait incidence from the young adult to the elderly was found; 5) A strong association was observed between the calcaneal and talar joint facet configurations: continuous vs. smooth, demarcated vs. angular, and separate vs. grooved; and 6) The depth of the anterior and middle talar facets of the calcaneus was greater in the separate type. Taking these results and the results of previous studies into consideration, it is concluded that the morphological variation in talar joint facets of the calcaneus may be regarded as not only one of the infracranial nonmetric traits under genetic control, but also a trait of some functional significance.