Does the iliolumbar ligament prevent anterior displacement of the fifth lumbar vertebra with defects of the pars?

We studied 23 patients with spondylolysis of the fifth lumbar vertebra (L5) and 20 with spondylolytic spondylolisthesis at this level, All were more t han 40 years of age, The transverse processes at L5 sere significantly wide r in the former group than in the latter, We also dissected 56 cadavers to study the morphological relationship between the transverse process of L5 a nd the iliolumbar ligament, and found that the wider transverse process is associated with increased width of the posterior band of the iliolumbar lig ament, If a patient with pars defects has nide transverse processes at L5, the lum bosacral junction may be stabilised by wide posterior bands of the iliolumb ar ligament and the fifth lumbar vertebra by the ligament, preventing anter ior displacement.