Correlation between sagittal morphology of lower lumbar end plate and degenerative changes in patients with lumbar disc herniation.

Objective: As an important anatomic factor in the process of lumbar disc herniation (LDH), the correlation between end plate sagittal morphology and intervertebral disc degeneration (IDD) is unclear. Moreover, research on imaging data of lumbar end plate in patients with LDH is still insufficient. Our study aimed to observe the morphological change of the lower lumbar end plate (L3-S1) in patients with LDH on magnetic resonance imaging (MRI) and analyze its correlation with the degree of IDD.

Materials and methods: A total of 116 patients were included in the study. Based on their MRI, we divided end plates into three types (concave, flat, and irregular), assigned intervertebral discs with Grade I-V given 1-5 points successively according to the Pfirrmann system, and determined whether there was Modic change of each end plate. The correlation between the morphology of the end plate and the degree of IDD was analyzed.

Results: There was an excellent interobserver agreement for each item we analyzed (interclass correlation coefficient >0.75). Concave end plate appeared most frequently (187, 53.7%) and was mainly distributed in L3/4 and L4/5, whereas irregular end plate was the least common type (54, 15.5%) and mainly concentrated in L5/S1. The IDD degree of the corresponding disc increased gradually from concave (3.27 ± 0.81) to irregular end plates (4.25 ± 0.79) (P < 0.05). Irregular end plates were more likely to have Modic changes than concave and flat end plates (P < 0.05).

Conclusion: The sagittal morphology of the lower lumbar end plate is related to modic changes and degree of IDD (based on the Pfirrmann grading system) in patients with LDH, and the concave end plate mostly reflects a lower degree of lumbar disc degeneration, which has substantial clinical significance.