Lumbosacral Transitional Vertebrae Are Associated with Lumbar Degeneration: Evaluation of 3855 Consecutive Abdominal CT Scans

Purpose: To assess the prevalence of lumbosacral transitional vertebra (LSTV) and associated lumbar degenerative changes on abdominal computed tomography (CT) scans in a white population.

Methods and Materials: A retrospective picture archiving and communications system search for abdominal CT studies performed during 2017 at our hospital was conducted. Studies not showing the lumbar spine fully were excluded. The search yielded 3855 CT studies that were assessed for the presence of LSTV using the Castellvi classification. Positive studies were further evaluated for disk degeneration (DD) and facet joint degeneration (FD). The degree of degeneration was assessed at all lumbar levels and graded as normal, mild, moderate, or severe. A control group of 150 patients without LSTV was selected at random with similar mean age (62.1 years) and sex distribution (63% male) to the study group. The slice thickness of the CT scans was 0.3 mm. Statistical SPSS software, v. 24.0 (SPSS Inc., Chicago, IL) and multivariate logistic regression were used for the analysis.

Results: LSTV was found in 1079 (28%) studies: Castellvi type I in 70%, type II in 17%, type III in 9%, and type IV in 4% of cases. After adjustments for age and sex, the prevalence of DD was significantly higher in Castellvi type II group at levels from L1–L2 to L4–L5, and in type III and IV groups at L4–L5 than in the control group. At L5–S1, the prevalence of DD was significantly higher in the control group than in type II, III, or IV groups (p < 0.001, p < 0.001, and p = 0.007, respectively). When comparing type I and control groups, the prevalence of DD was significantly higher in the type I group only at L2–L3 (p = 0.05). After combining Castellvi types II, III, and IV into one group, significant differences were found at every lumbar level.

After adjustments for age and sex, the prevalence of FD was significantly higher at L4–L5 in every Castellvi group than in the control group. In the type II group, the prevalence of FD was also significantly higher at L2–L3 and L3–L4 and in the type IV group at L1–L2 and L2–L3 than in the control group. Again, when Castellvi types II, III, and IV were combined into one group, significant differences were found at lumbar levels L2–L3, L3–L4, and L4–L5.

Conclusion: LSTVs of Castellvi type II, III, and IV are associated with generalized lumbar degeneration, whereas Castellvi type I shows no clear association with lumbar degeneration.