Figure 4.

The step-by-step illustration of interlaminar contralateral endoscopic lumbar foraminotomy. (A) Step 1: midline laminotomy. (B) Step 2: drill contralateral lamina and unroof lateral recess of the contralateral side. (C) Step 3: decompress contralateral foramen by undercutting medial facet and removing ligamentum flavum. (D) Endoscopic visualization of decompressed root (*). (E) The pre-operative (left) and post-operative (right) CT images showed the widened foramen (dotted line circle) after removing the tip of superior articular process.