Transition analysis of age-related changes to the distal radius and ulna in a modern South African population

Abstract

A forensic anthropologist’s primary role involves establishing a biological profile from unknown skeletal remains. Extensive research has been conducted on methodology to construct the biological profile from adult remains. However, the estimation of subadult biological parameters is lacking, mainly as a result of the paucity of known skeletal material for research. Numerous methods have been assessed to conduct subadult age estimation, with epiphyseal fusion being the preferred method for the adolescent age cohort. The application of epiphyseal fusion has been extensively researched on several populations; differences in the maturation rate of populations have been observed and demonstrate the need for population-specific standards. While some studies have been conducted on South Africans, the approach lacks the robust statistical component to make the method compliant with standards of best practice required of forensic methodology. The aim of the current study was to re-evaluate age estimation standards from epiphyseal fusion of the distal radius and ulna. A sample of 782 hand-wrist radiographs of male and female black and white South Africans were collected from Mediclinic, Bloemfontein. The ages ranged between eight and 30 years. Degree of epiphyseal fusion for the radius and ulna was assessed and scored using a four-stage system. Differences in the rate of fusion between the radius and ulna, the sexes, as well as the population groups were assessed with a Kruskal-Wallis test. Transition analysis and Bayesian statistics were applied to obtain the maximum likelihood age estimate and the average age of transition among the stages, respectively. Significant differences (p<0.05) were noted between the fusion of the radius and ulna. Furthermore, there were no significant differences between males and females. While significant differences were noted between black and white South Africans, the differences only amount to a few months and therefore do not justify separating the populations for the creation of standards, as group separation would affect the practical applicability of the method. Complete fusion was observed between the ages of 16 and 19 years in the pooled sample (95% CI). The results indicate an earlier age of complete fusion compared to previous South African studies, particularly for the males.