Anatomical assessment of the relationship between the aortic bifurcation and the vertebral body in individuals with normal vertebral column structure using computed tomography angiography.

BACKGROUND: Anterior approaches to the lumbar spine, particularly anterior lumbar interbody fusion (ALIF) at L4-L5 and L5-S1, are increasingly common. Vascular injury involving the aortic bifurcation (AB) is a serious, potentially fatal complication, so precise knowledge of the AB's relationship to adjacent vertebrae is essential for safe planning. This study determined the vertebral level of the AB and measured the perpendicular distance (X) between the AB and the anterior vertebral surface using multidetector computed tomography angiography (MDCT-CTA), and evaluated variation by sex and age. MATERIALS AND METHODS: Ninety individuals (47 males, 43 females; age range, 5-89 years; mean age, 55.3 ± 14.8 years) who underwent thoracoabdominal MDCT-CTA between 2010 and 2012 were studied retrospectively; individuals with scoliosis were excluded. A novel 15-quadrant grid template mapped the coronal position of the AB on each lumbar vertebral body and disc, and X (mm) was measured. Reporting follows an established checklist for anatomical variation studies. Nonparametric tests were applied where appropriate. RESULTS: The AB was most frequently at the L4 vertebral body level (58.9%; n = 53), followed by the L3-4 (17.8%) and L2-3 (12.2%) discs. Mean X was 5.07 ± 3.44 mm (range, 1.10-25.90 mm). No significant difference in X was found between sexes or quadrant positions. A trend toward caudal AB displacement with advancing age was observed. CONCLUSIONS: The AB most commonly lies at the L4 vertebral body level in adults, with notable variability. X provides novel preoperative data that may guide safer retraction during anterior lumbar surgery; caudal migration in elderly patients warrants particular attention.