Study design: A cross-sectional population-based magnetic resonance imaging study of Schmorl nodes (SN) in the lumbar spine.
Objective: To determine the prevalence and potential determinants of SN, and their association with intervertebral disc degeneration.
Summary of background data: SN represent intravertebral disc herniation and are commonly seen in the spine. Their reported prevalence and determinants vary, and their association with disc degeneration remains uncertain. Data based on this large scale population-based study of intervertebral disc degeneration would provide important information for understanding SN and their pathomechanism.
Methods: Sagittal T2-weighted magnetic resonance imagings of the lumbar spine were analyzed in 2449 volunteers. Two independent observers assessed the images for the presence of SN, and scored for additional radiologic features (e.g., severity of degeneration, presence of disc bulge/extrusion). Subject demographics were assessed by standardized questionnaire.
Results: SN were found in 16.4% (n = 401; 219 males, 182 females; mean age = 42.3) of our study population (981 males, 1468 females; mean age = 40.4), being most common at L1/2 and L2/3 (54.1%). Multivariate logistic regression revealed that males, taller and heavier individuals had an increased likelihood of SN (P < 0.005), but association between SN and age were not discerned. Overall presence of SN was associated with disc degeneration (P < 0.001), and linearly correlated (R = 0.97) with increase in severity of degeneration. SN were particularly associated with severe disc degeneration at L1/2 and L2/3 with 22- to 15-fold increased odds, respectively (P < 0.0001), but less than 5-fold increased odds (P < 0.001) were noted in the lower lumbar spine.
Conclusion: In a population-based cohort, 16.4% of Southern Chinese subjects had SN at 1 or more lumbar levels. Males, taller and heavier individuals had increased likelihood of SN. Interestingly, SN were highly associated with severity of disc degeneration.