Fig. 2

54-year-old female with L4/5 and L5/S1 double-level spondylolytic spondylolisthesis. a The preoperative radiograph showed a distinct lumbosacral deformity (L4–S1 height = 51.3 mm, L4-SVA = 34.3 mm) and sagittal imbalance (L4–S1 lordosis/LL = 44.5%, C7-SVA = 43.8 mm). b Postoperative radiograph following L4/L5 and L5/S1 dual-level TLIF and posterior instrumentation from L4 to S1 showed a good restoration of L4–S1 region (L4–S1 height = 68.5 mm, L4-SVA = 18.7 mm), an optimal redistribution of lumbar lordosis (L4–S1 lordosis/LL = 67.5%), and a harmonic global sagittal balance (C7-SVA = 8.4 mm). c Radiograph obtained at 4 years after surgery revealed that both lumbosacral region and global sagittal alignment maintained well.