Purpose Lumbosacral transitional vertebrae (LSTV) are congenital spinal anomalies, in which an elongated transverse process of the last lumbar vertebra fuses with varying degree to the “first” sacral segment. The presence of an LSTV may alter spine biomechanics. Consensus whether an LSTV is related to symptoms and spinal degeneration is lacking. We therefore determined the prevalence of LSTV in the population-based Rotterdam Study (RS) and assessed the relationship between LSTV and chronic low back pain and lumbar disc degeneration (LDD).  

Methodsand Materials On standing anteroposterior pelvic radiographs from the RS, presence and type of LSTV was scored using Castellvi’s classification, distinguishing non-fused LSTV (type I and II) and fused LSTV (types III and IV). Chronic low back pain was defined as reported low back pain lasting more than 3 months in conformance with the WHO definition. LDD (L1-L4) was radiographically defined as presence of osteophytes and disc space narrowing, using a semi quantitative scoring method (grade 0-3). Logistic regression, adjusted for age, sex and BMI was used to analyze the association between presence of an LSTV and its subtypes and chronic low back pain and LDD.

Results Among 4896 individuals, the prevalence of LSTV was 13.8% and higher in males compared to females (56.9% vs. 43.1%, P<0.001). The presence of LSTV (all types) did not show a significant association neither with chronic low back pain (OR: 1.25; 95% CI: 0.99 to 1.59) nor with LDD (OR: 1.20; 95% CI: 0.92 to 1.52). Nevertheless, non-fused LSTV (type I and II) were associatedwith chronic low back pain(OR: 1.40; 95% CI: 1.03 to 1.90) but not the fused LSTV (OR: 1.04; 95% CI: 0.72 to 1.50).

Conclusion The presence of an LSTV was relatively common in this study in the general population and more frequent in men compared to women. Furthermore, we found that non-fused types LSTV are associated with chronic low back pain, suggesting unfavorable biomechanics.