Fig. 4

A 52-year-old female with a symptomatic ASD at the L3/4 level. Primary transforaminal lumbar interbody fusion was performed to treat the disc herniation at L4/5 2 years ago. OLIF without posterior instrumentation was employed to treat ASD at L3/4. a, b Preoperative X-ray shows loss of intervertebral disc height at L3/4, and posterior instrumentation and an intervertebral cage were placed appropriately at L4/5. Preoperatively, the IVH was 8.9 mm, the IFH was 15.4 mm, and the IFA was 1.76 cm². c, d Preoperative MRI shows inclusive disc herniation at L3/4 and compression of right L4 nerve root. No obvious proliferation or calcification of the ligamentum flavum or zygopophysis was noted. Preoperatively, the APD was 6.6 mm and the CSA was 0.70 cm². e, f Postoperative X-ray shows the intervertebral cage at L3/4 was well in place, and the IVH, IFH, and IFA were significantly increased. Postoperatively, the IVH was 14.8 mm, the IFH was 18.8 mm, and the IFA was 2.85 cm². g, h Postoperative MRI shows the spinal canal was apparently enlarged and effective indirect decompression was achieved. The APD was improved from 6.6 mm preoperatively to 8.6 mm postoperatively, and the CSA postoperatively was 0.92 cm², which was apparently larger than 0.70 cm² preoperatively