Fig. 4

The patient complained of severe left radicular pain for 12 months. He could not walk for 3 months due to severe left buttock and leg pain. Left L4/5 LLSC stenosis in both zones 1 and 2 was confirmed. We confirmed the totally decompression by postoperative CT and MRI. The leg pain was relieved immediately after the operation. No lumbar instability was indicated in the final follow-up. a, b Preoperative X-ray in AP and lateral view. c Preoperative sagittal CT scans indicated stenosis of the retrodiscal space (zone 1) on the left at L4/5 (red circle). d Preoperative axial CT scans indicated upper bony lateral recess (zone 2) stenosis on the left at L4/5 (red circle). e, f Preoperative sagittal and axial T2-weighted MRI scans showing the L4/5 left zone 1 stenosis caused by a lumbar disk bulge anteriorly, and hypertrophied, curled ligamentum flavum posteriorly (red circle). g, h Fluoroscopy during surgery demonstrates the trajectory of the trephine in the first foraminoplasty in the AP and lateral views. i, j Fluoroscopy during the operation shows the trajectory of the trephine in the second foraminoplasty in the AP and lateral views. k, l Three months postoperative sagittal and axial CT bony-window scans clearly demonstrate complete decompression of zones 1 and 2. m, n Three months postoperative sagittal and axial T2-weighted MRI scans indicate that the nerve root was decompressed without recurrence. o, p Postoperative flexion-extension x-rays at the final follow-up confirm that no lumbar instability occurred