Abstract: The purpose of this study was to investigate the value of sagittal lumbar flexion angle, end plate flexion depth and the difference of cross-sectional area of bilateral psoas major muscle in the diagnosis of lumbar disc herniation (LDH), as well as the relationship with the degeneration. We selected 120 cases of LDH patients as the observation group, and 100 healthy people as the control group. The Lumbar CT examination was performed on both groups. The results showed that there were statistically significant differences between the observation group and the control group in the following items:the average endplate buckling depth, the average sagittal plane buckling angle and the average psoas major cross-sectional area (L₃-S₁). Compared with patients of Pfirrmann grading Ⅱ-Ⅲ in observation group, the average depth of the end plate buckling of L₃-S₁ had statistically significant 386 differences with those of patients in Pfirrmann grading Ⅳ-Ⅴ, as well as the average sagittal buckling angle and the average psoas major cross sectional area (P<0.05). The area under the ROC curve of Pfirrmann grade Ⅳ-Ⅴ diagnosed by the three parameters were 0.701, 0.890 and 0.771. This study confirmed that Sagittal curvature angle, end plate flexion depth and the difference of cross-sectional area of bilateral psoas major muscle are related to the degree of intervertebral disc degeneration in patients with LDH, which has certain value in the diagnosis of intervertebral disc degeneration.

Key words: lumbar CT, sagittal flexion angle, end plate flexion depth, bilateral psoas major muscle cross-sectional area difference, lumbar disc herniation