Morphological analysis of thoracic vertebrae: a 3D approach for human identification

Aspalilah Alias^1,2, Rani Sakaran^1,3, Choy Ker Woon⁴, Ku Mastura Ku Mohd Noor⁵, Nurul Hannim Zaidun⁴, Ng Wei Lin⁶, Eric Chung⁶

¹Department of Basic Sciences, Faculty of Dentistry Universiti Sains Islam Malaysia (USIM), Malaysia; ²Department of Forensic Odontology, Faculty of Dental Medicine, Universitas Airlangga, Indonesia; ³Department of Anatomy, Asian Institute of Medicine, Science and Technology (AIMST), Malaysia; ⁴Department of Anatomy, Faculty of Medicine, Universiti Teknologi MARA (UiTM), Sungai Buloh Campus, Selangor, Malaysia; ⁵Faculty of Medicine and Health Sciences, Universiti Sains Islam Malaysia (USIM), Malaysia; ⁶Department of Biomedical Imaging, Faculty of Medicine, University of Malaya (UM), Kuala Lumpur, Malaysia

Objective: Forensic anthropologists systematically investigate bones to obtain the deceased's identification profile, such as ancestry, sex, age at death, and stature. However, in a mass disaster involving many victims, identifying remains becomes more complex. The thoracic vertebra has unique characteristics, including a sturdy structure, a facet for articulating ribs on the vertebral body, and a transverse process not seen in other bones. The aim was to study variations in the size and shape of the thoracic vertebrae for the identification of Malaysian individuals.
Methods: 144 CT images of thoracic vertebrae in Malaysian males of different ethnicities (Chinese 47, Indian 53, Malay 44) were collected retrospectively. Three-dimensional reconstruction of the thoracic vertebrae was performed using relevant software and the CT images. Checkpoint and MorphoJ software were used for landmarking and analysis in geometric morphometric analysis. The landmark editor IDAV was used to visualize thoracic vertebrae for the different groups.
Results: Procrustes ANOVA, discriminant analysis, canonical variate analysis, and principal component analysis showed significant differences between the Malay, Chinese, and Indian populations in the size and shape of the vertebrae with p<0.05. Discriminant function analysis showed that around (91 – 98%) of the thoracic bone can differentiate between Malays, Chinese, and Indians in Malaysia.
Conclusion: Forensic identification, such as sex, age, and ethnicity, is produced based on variations in the shape and size of the thoracic vertebrae. This is important for the police and judicial system of the country to assist in the direction of police investigations, court proceedings, and the identification of remains in mass disasters.

Keywords: forensic anthropology; geometric morphometric; identification; thoracic bone

Ethical statement: Ethical approval was obtained from the Medical Research Ethics Committee, University Malaya Medical Centre (MREC) with the ID number 2020728 – 8925, and the research was funded under Grant FRGS/1/2023/SKK06/USIM/03/2.