Sternal human variability and population affinity: Frequency of discrete traits and their relationship with sex and age.

Sternal morphological variations differ among populations and are influenced by the interaction between inheritance, development, and environment. There are currently no studies that include all variability from a morphogenesis approach following a homogeneous definition. The aims of this study were (a) to develop a standardized method for the anatomical study of the sternum; (b) to analyze the prevalence of the morphological variations and their relationship between sex and age; (c) to compare the results with other populations. The sterna of 155 skeletons from a Spanish population were studied. The age at the time of death was 17 to 97 years. We analyzed two metric and 22 sternal morphological variations described in the literature and designed an illustrated atlas. The atlas was validated using the intraclass correlation coefficient (ICC). A descriptive statistical analysis was conducted to measure the prevalence and relationship between sex and age. To analyze the interpopulation variability, we compared our results with those from other authors. The atlas with definitions and reference images improves the observation and detection of all morphological variations of the sternum (ICC = 0.90). The dependence between the morphological traits and sex was significant for the variations in the sternal angle, the number of esternebra, and the development of the xiphoid process. No significant differences were found between age group and morphological traits. The expression of the sternal morphological variation and sex are population-specific. The results will help standardize future studies and provide valuable information on the variability of the sternal morphological variation.