Fig. 1From: Mild (not severe) disc degeneration is implicated in the progression of bilateral L5 spondylolysis to spondylolisthesisPictorial representation of the five finite element models of lumbosacral spine representing various states of the L5-S1 intervertebral disc with or without a bilateral spondylolytic defect at L5. Compared with the INTACT model, a disc height loss of 50% in the mid-sagittal plane was modelled in the Lytic-Mild-Degen-Collapsed and Lytic-Severe-Degen-Collapsed modelsBack to article page