Abstract:[Objective]The objective of this study was to investigate the relationship between intervertebral disc herniation at the L5/S1 level and the development of posterior articular processes.[Method]A retrospective analysis was conducted on patients between 2017 and 2020, categorizing them into two groups: those with L5/S1 lateral disc herniation (LDH group) and those without lumbar disc herniation (normal group), based on MRI findings. Magnetic resonance imaging (MRI) was used to measure the facet joint angle (FJ) at the L5/S1 level and the adjacent L4/5FJ in both the herniated and normal groups.The difference in FJ between the left and right sides was calculated. A difference exceeding 10° was defined as bilateral FJ asymmetry.Additionally,the sum and difference of the corresponding angles were computed.Single-factor analysis and multivariate logistic regression were employed to analyze the factors influencing L5/S1 LDH.[Result]A total of 102 cases were included in the LDH group,while 107 cases were included in the normal group.Univariate analysis revealed differences between the two groups in terms of age, gender,BMI, L4/L5(∠C), L5/S1(∠C), L4/L5(∣∠α-∠β∣), and in L4/5 asymmetry，with non-significant differences (P>0.05).However,L5/S1(∣∠α-∠β∣),L5/S1 asymmetry,absolute difference between L4/5 and L5/S1∠C,absolute difference between L4/5 and L5/S1∠α,and absolute difference between L4/5 and L5/S1∠β were significantly higher in the LDH group compared to the normal group (P<0.05).Following multiple-factor logistic regression analysis,L5/S1(∣∠α-∠β∣) (OR=1.245, P<0.05) and the absolute difference between L4/5 and L5/S1∠C(OR=1.049, P<0.05) emerged as independent risk factors for L5/S1 lateral protrusion (P<0.001).[Conclusion]A correlation exists between the absolute difference in the angle between L4/5 and L5/S1∠C and the angle (∣∠α-∠β∣) at the L5/S1 level in cases of lateral LDH at L5/S1.