The contribution sagittal counting and iliolumbal ligament in numbering of lumbosacral transitional vertebra

Aim: Transitional vertebra are one of the most common variations in the lumbosacral region. This study aims to evaluate whether sagittal counting and determination of iliolumbar ligament (ILL) level can be used in lumbosacral transitional vertebra (LSTV) numbering. Method: 156 non-contrast lumbar magnetic resonance imaging (MRI) examinations were included in the study. Patients with stage 2 and higher spondylolisthesis, spinal-pelvic trauma, infection, and spinal surgery history were excluded from the study. T1W cervicothoracic sagittal counting and T2W sagittal images were evaluated in terms of transitional vertebra, and axial oblique T1W images directed to the lumbosacral junction were assessed to determine the level of ILL. Student test and chi-square test were used for statistical evaluation. Results: Normal lumbosacral segmentation was observed in 118 of 156 cases (75.6%), sacralization was observed in 22 cases (14.1%), lumbalization was observed in 16 cases (10.3%), in total 38 cases were observed. The frequency of transitional vertebra was found to be 24.4%. The LSTV rate was found to be 26.2% in women and 20.4% in men. Conclusion: ILL usually originates from the transverse process of the L5 vertebra in cases without LSTV. However, in more than half of those with LSTV, the ILL is located outside of the L5 localization. Therefore, the ILL position cannot be used to determine lumbar levels in patients with LSTV. To make an accurate assessment and an accurate enumeration, each level of the vertebral column must be thoroughly evaluated with direct radiography or MRI.