Relationship between morphology of iliolumbar ligament and lower lumbar disc degeneration

Previous imaging studies have shown little difference in the degree of disc degeneration between L4-L5 and L5-S1 . We hypothesized that because the mo rphology of the iliolumbar ligament affects the stability of the lumbosacra l junction, then it could determine the lower lumbar disc degeneration. Fif ty-three male and 47 female patients were classified into three groups acco rding to their disc degeneration grade-those in whom the L5-S1 I disc was l ess degenerated (group A), more degenerated (group B), and equally degenera ted (group C) compared to the L4-L5 disc on T2-weighted magnetic resonance images. The length and direction of the anterior and posterior iliolumbar l igaments were measured on T1-weighted axial images. The iliolumbar ligament was shorter in group A than in group B or C, and was oriented significantl y more posteriorly in group A than in groups B or C. The morphology of the iliolumbar ligament, especially its length and direction, can be a factor i nfluencing the development of disc degeneration at IA-LS and L5-S1.