Abstract

Background: The thoracolumbar junction (TLJ) includes the T11–L2 vertebral segments. It is a pivotal biomechanical transition zone between the rigid thoracic spine and the more mobile lumbar spine. Accurate morphometric data from this region are crucial for understanding human axial biomechanics and supporting forensic investigations. Objective: This study was designed to establish a normative multi-detector computed tomography (MDCT) database of the human thoracolumbar junction (T11–L2) in an adult population. Specifically, the primary objectives were to quantify normal vertebral and pedicle dimensions and to investigate the prevalence of congenital rib anomalies. The ultimate clinical goal is to translate these anatomical metrics into practical guidelines for spinal surgery and tools for forensic sex estimation. Materials and Methods: A retrospective analysis of 517 adults (277 men, 240 women) who received thoracic CT for various clinical indications was conducted. Morphometric parameters, including anterior, middle, and posterior vertebral heights; transverse and sagittal pedicle diameters; pedicle length; and transverse pedicle angle, were systematically measured. Costal variations, including hypoplastic and supernumerary ribs, were carefully recorded. Results: Vertebral and pedicle linear dimensions were generally larger in men than in women. The mean transverse pedicle diameter (TPD) increased progressively from T11 to L2. Significant sexual dimorphism in TPD was observed at the T11, L1, and L2 levels (p < 0.05), whereas both transverse (p = 0.168) and sagittal (p = 0.251) pedicle dimensions remained statistically comparable between sexes exclusively at the T12 transitional segment. The transverse pedicle angle (TPA) showed a consistent, increasing medial trajectory from T11 (~21°) to L2 (~28°) in both sexes, with no significant sex-based difference (p > 0.05). The overall prevalence of congenital rib variations was 18.57%. The most frequent structural anomaly was 12th-rib hypoplasia. Conclusions: This study provides a detailed morphometric baseline for the TLJ in an adult cohort (n = 517) of Turkish adults. The findings show that while absolute pedicle size and volumetric mass are influenced by sexually dimorphic physical geometry, the spatial trajectory and angulation of the pedicles (TPA) are determined by biomechanical principles that are independent of sex. In addition, pronounced sexual dimorphism and a high prevalence of unique costal variations were observed. These factors provide valuable biological markers that serve as reliable radiological fingerprints for forensic anthropologists who estimate sex from skeletal remains and identify unknown individuals.

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