Lumbosacral transitional vertebrae: a review of prevalence, classification, morphology, imaging and clinical implications
Year: 2026
Type: article
Abstract: Lumbosacral transitional vertebrae (LSTV) are morphological abnormalities at the lumbosacral junction, where either the last lumbar vertebra acquires sacral characteristics or the first sacral segment retains lumbar characteristics. The subset of individuals in whom the transitional segment is judged to be the source of low back pain (LBP) or radiculopathy is termed Bertolotti's syndrome. Most LSTV is an incidental imaging finding in an asymptomatic individual, and the two terms are not interchangeable. This review investigates the classification systems for LSTV, the anatomical and biomechanical effects of the transitional segment, and the imaging modalities used for identification and classification. We examine how the Castellvi classification system fails to distinguish all morphological characteristics, how surrounding segments and joints are affected by LSTV, and the efficacy of imaging and numbering techniques. LSTV are morphological abnormalities at the lumbosacral junction, where either the last lumbar vertebra acquires sacral characteristics or the first sacral segment retains lumbar characteristics. The prevalence of LSTV has been reported to range from 5-43%, indicating potential variability. The correlation between LSTV and LBP is commonly debated, with studies finding that LSTV does not directly cause LBP. The heterogeneity of LSTV presentation reflects a continuous morphological spectrum that makes categorical classification systems challenging. The clinical management of LSTV remains hindered by inconsistent vertebral numbering, variable imaging interpretation, and a lack of standardized classification. The current Castellvi classification system leads to inconsistency of imaging, identification, and classification of LSTV, contributing to misidentification of the source of LBP and treatment of Bertolotti's syndrome. As a result of identification, classification, and numbering inaccuracies of techniques and imaging modalities, LSTV patients are at higher risk of experiencing wrong level spine surgery (WLSS). A proposed solution to these discrepancies is the application of artificial intelligence (AI) for more precise spinal imaging classifications. This review investigates the classification systems for LSTV, the anatomical and biomechanical effects of the transitional segment, and the imaging modalities used for identification and classification. We examine how the Castellvi classification system fails to distinguish all morphological characteristics, how surrounding segments and joints are affected by LSTV, and the efficacy of imaging and numbering techniques.
Source: Journal of Spine Surgery
Institutions: University of Minnesota, Augusta University
Language: English
Subfield: Orthopedics and Sports Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223892422