Forensic Significance of Sternal Fusion in Adult Age Estimation: An Autopsy Study in North India

Age estimation is an important component of forensic identification, particularly in cases involving unknown, decomposed, mutilated, or skeletonized human remains. Following completion of skeletal maturity, commonly used indicators such as epiphyseal fusion become less reliable, making evaluation of other skeletal structures necessary. The sternum is considered useful in forensic age estimation because of its resistance to decomposition and progressive fusion changes during adult life. The present study was conducted to evaluate the relationship between age and fusion of different sternal elements in the North Indian population.

A prospective cross-sectional study was conducted in a tertiary care centre of southern Haryana, India. A total of 115 medico-legal autopsy cases of known age, aged 15 years and above, were included in the study. The sternum was dissected during autopsy, and the fusion status of the body of the sternum, xiphisternal joint, and manubriosternal joint was assessed grossly. Statistical analysis was performed using IBM SPSS Statistics for Windows, version 29.0 (IBM Corp., Armonk, New York, United States), and associations between fusion patterns and age groups were evaluated using Pearson's Chi-square test.

Fusion of the body of the sternum was observed in almost all cases and did not show a statistically significant association with age (p = 0.910). In contrast, fusion of the xiphisternal joint and manubriosternal joint increased progressively with advancing age. Chi-square analysis demonstrated a statistically significant association between xiphisternal joint fusion and advancing age (χ² = 10.152, p = 0.038), while manubriosternal joint fusion approached statistical significance (χ² = 7.467, p = 0.058). Xiphisternal fusion was absent below 25 years and became progressively more frequent in older age groups, whereas manubriosternal fusion was predominantly observed after 35 years of age. Female cadavers demonstrated slightly earlier and higher fusion rates in advanced age groups compared to male cadavers. Binary logistic regression demonstrated that xiphisternal and manubriosternal fusion were significant independent predictors of age ≥45 years, with the combined model showing excellent discriminatory ability (area under the curve (AUC) = 0.896).

Fusions of the xiphisternal and manubriosternal joints are potential supportive indicators demonstrating significant age-associated trends, particularly beyond the fourth decade of life. Fusion of the body of the sternum has limited forensic significance because of its early completion and lack of progressive age-related variation. Assessment of sternal fusion should be interpreted in conjunction with other skeletal indicators and population-specific standards for improved medico-legal accuracy.