The Difference in Gender Affects the Pathogenesis of Ligamentum Flavum Hypertrophy

INTRODUCTION: Gender differences may play a role in the pathogenesis of lumbar spinal stenosis. However, few reports that discuss the effects of gender differences in ligamentum flavum (LF) hypertrophy have been published, and no study has investigated the relationship between LF thickness and the quantitative value of intervertebral disc (IVD) degeneration. This study aimed to investigate the impact of gender on the pathomechanisms underlying LF hypertrophy, focusing on the relationship among LF thickness, IVD degeneration, and age. METHODS: The subjects include 100 patients with low back pain and leg numbness, tingling, or pain. We measured LF thickness and the T2 values of IVDs using MR imaging and analyzed the relationship among LF thickness, T2 values of IVDs, and age. The interclass correlation coefficient (ICC) was calculated as the inter-rater reliability between the LF thickness values measured by two investigators. RESULTS: ICC was calculated for the two measurements of LF thickness (r = 0.923, 95% CI: 0.907-0.936). No statistically significant difference in the T2 values of IVDs was observed between females and males from L2/3 to L5/S. There were significantly negative linear correlations between LF thickness and the T2 values of IVDs at all levels, but this correlation was not observed in females at L4/5. There were significantly negative linear correlations between age and the T2 values of IVDs from L2/3 to L5/S for all patients, females, and males (r = 0.422-0.756). In addition, there were significantly positive linear correlations between age and LF thickness from L2/3 to L4/5 for all patients (r = 0.329-0.361) and females (r = 0.411-0.481). Correlations were not observed for males at all levels or for all patients at L5/S. CONCLUSIONS: The relationships identified among LF thickness, age, and IVD degeneration suggest that gender differences play a role in the pathogenesis of LF hypertrophy.