Radiographic Assessment of the Ischiopubic Index in Adult Nigerians for Sex Estimation and Clinical Applications
Abstract
Background: The pelvis is the most sexually dimorphic region of the human skeleton and plays a pivotal role in forensic anthropology, clinical anatomy, and medicolegal investigations. The ischiopubic index has been widely used for biological sex estimation. Aim: This study aimed to determine the ischiopubic index among adult Nigerians in Port Harcourt, Rivers State. Methodology: A retrospective descriptive cross-sectional study was conducted using 100 archived anteroposterior pelvic radiographs (50 males and 50 females) obtained from the Department of Radiology, University of Port Harcourt Teaching Hospital. Pubic length and ischial length were measured from standardised anatomical landmarks, and the ischiopubic index was calculated as (Pubic Length/Ischial Length) × 100. Data were analysed using IBM SPSS version 25. An independent-samples t-test and discriminant function analysis were performed, with statistical significance set at p < 0.05. Results: The mean pubic length was 79.14 ± 5.95 mm in males and 76.10 ± 9.21 mm in females, with no significant sex difference (p = 0.053). Males had significantly greater ischial lengths than females (84.08 ± 5.99 mm vs. 71.97 ± 9.13 mm; p < 0.001). Conversely, females exhibited a significantly higher ischiopubic index than males (105.81 ± 1.28 vs. 94.09 ± 0.84; p < 0.001). Discriminant function analysis yielded the equation D = −1.802 − 1.333(Pubic Length) + 1.349(Ischial Length) and demonstrated excellent discriminatory performance (Eigenvalue = 38.506, Canonical Correlation = 0.987, Wilks' Lambda = 0.025, χ² = 356.616, p < 0.001), correctly classifying 100% of the original and cross-validated cases. Conclusion: The study demonstrates that the ischiopubic index is a reliable indicator of sexual dimorphism in adult Nigerians from Port Harcourt. The derived discriminant function provides population-specific reference data that may be useful for forensic identification, anthropological research, and clinical anatomical practice.