Fig. 2

L4 degenerative spondylolisthesis with lumbar canal stenosis in a 65-year-old female (patient No. 15 in Table 1). a Lateral radiograph before surgery. b Lateral radiograph 2 months after surgery (XLIF plus SP-PPS in lateral decubitus position). Sagittal and axial magnetic resonance imaging before surgery (c, e) and 2 weeks after surgery (d, f). An increase in cross-sectional spinal canal area (CSA) (from 58.1 mm² to 66.8 mm²) and diameter (from 4.2 mm to 9.1 mm) were observed after surgery, but the change was small at 2 weeks after surgery. However, the patient’s preoperative symptoms have improved, and she is progressing satisfactorily after the surgery