A New radiographic feature of lower lumbar disc herniation in young patients.

PURPOSE: In our study, we assessed the condition of the lumbar laminae defect of L5, other than the defect of spina bifida, in a group of different ages with lower lumbar disc herniation (LDH). We hypothesize that the laminae defect of L5 may be a radiographic feature in young patients with lower LDH.

METHODS: We analyzed the features of the laminae of L5 from the anteroposterior X-rays of the lumbosacral spine in 342 patients suffering from lower LDH. The patients were divided into three groups depending on age: age <45 (group A), 45 ≤ age ≤ 59 (group B) and age>59 (group C). The width of the unilateral laminae of L5 was measured by drawing a line named "a" from the upper margin to the lower margin. Then the line "a" was extended downward to the bottom of the laminae interval space to perform a new line named "b". We assessed the condition of the laminae defect of L5 using the ratio "a/b" in each group.

RESULTS: The average ratio "a/b" in each group was: 0.47 ± 0.06 in group A, 0.51 ± 0.06 in group B, and 0.52 ± 0.06 in group C. The average ratio "a/b" of group A was significantly smaller than group B and group C (P<0.05). However, there was no statistical difference of the average ratio "a/b" between group B and group C (P>0.05).

CONCLUSIONS: Laminae defects of L5 may be a congenitally potential risk factor leading to lower LDH in the young and this radiographic clue could be used for the diagnosis of symptomatic lower LDH patients. For asymptomatic people who encounter this radiographic feature, preventive advice could be provided.