Anteroposterior lumbar spine X-ray of L5 lamina for screening of possibility of lower lumbar disc herniation in young adults

Abstract Purpose: This study investigated the association between the height of L5 lamina under anteroposterior lumbar spine X-ray and lower LDH, to determine its significance to the onset of LDH in young adults.Methods: We conducted a retrospective study of 160 patients aged 18 to 39 years with lower LDH and 160 healthy controls. The anteroposterior lumbar spine X-ray was used to image features of the L5 lamina. The height of L5 lamina (“h”) and of the space between L4 and S1 lamina (“H”) were measured. The difference in height of L5 lamina in each study group was assessed as the ratio of “h/H”.Results: There was no significant difference in sex, age, occupation type, body mass index (BMI), family history or smoking status (p>0.05) between LDH group and the control group. The mean ratio (95% CI) of “h/H” in LDH and control group was 0.28 (0.26, 0.31) and 0.35 (0.32, 0.38) respectively, with statistical difference (p<0.05). The diagnostic accuracy of “h/H” ratio was investigated using the receiver operating characteristic (ROC) curve. The area under the curve was 0.835 (95% CI 0.789, 0.881), using a cut-off of 0.315 (sensitivity 0.806, specificity 0.794). A decrease in the “h/H” ratio, showed an increasing linear trend in the protrusion proportion of L4/5 segments (Z=5.943, p<0.05).Conclusion: Young adults with developmental defects of L5 lamina are more likely to develop lower LDH. Assessment of “h/H” ratio could be used for screening or prediction of asymptomatic or mildly symptomatic lower LDH in young adults.