A 31-year-old male presented with a 1-year history of persistent severe low back pain radiating into the left buttock, hip, and left great toe. The patient denied bowel or bladder symptoms. He underwent 6 months of conservative treatment, including therapeutic injections, without durable relief. On physical examination, motor strength was grossly normal. There was diminished left ankle reflex and decreased sensation over the left great toe. Computed tomography (CT) myelogram demonstrated evidence of bilateral L5 pars defects resulting in grade II spondylolisthesis at L5-S1 and foraminal stenosis. Standing x-rays re-demonstrated a grade II anterolisthesis of L5 on S1 (Figure 51.1). Because of his persistent symptoms, imaging findings, and failure of conservative measures, the patient was offered and elected to undergo a minimally invasive transforaminal lumbar interbody fusion (TLIF) (Figure 51.2).