Morphological analysis of the first rib for sexual dimorphism among Malaysian population using three-dimensional geometric morphometric method

Vollständiger Abstract

Worum geht es in dieser Arbeit?

The first rib possesses unique anatomical features that make it readily identifiable. This characteristic supports its use in sex estimation in forensic anthropology, particularly when the pelvis or skull is unavailable. Previous studies used linear morphometry based on linear measurements, neglecting shape element. Three-dimensional geometric morphometrics (3DGM) can assess both size and shape, providing a different approach in morphological analysis. Despite the important of population-specific variation of skeletal anatomy, studies on the Malaysian first rib are limited. The aim of the work was to investigate sexual dimorphism of the first rib in the Malaysian population and to evaluate its accuracy rate for sex estimation using 3DGM. CT scans of the right first rib of 376 Malaysians (188 males, 188 females) aged 18-69 were collected. Seventeen landmarks were applied using Stratovan Checkpoint. Shape variation of the first rib was quantified by 17 3D-landmarks and analyzed using geometric morphometric method done via MorphoJ, including Principal Component Analysis, Procrustes ANOVA and Discriminant Function Analysis (DFA) for sex classification. The Principal Component Analysis revealed that the first ten Principal Components accounted for 81.15% of the total variance in the right first rib. Procrustes ANOVA indicated significant differences in both the centroid size and shape (p < 0.05) of the right first rib between sexes. DFA, following cross-validation, demonstrated a classification accuracy of 86.17% for females and 83.51% for males, with an average accuracy of 84.84%. This study demonstrates statistically significant population‑specific sexual dimorphism in the Malaysian first rib using 3DGM. The observed shape and size differences support the use of the first rib as an alternative skeletal element for sex estimation in forensic anthropology.