Fig. 1

Surgical procedures of lumbar endoscopic unilateral laminotomy bilateral decompression. a and b The inferior edge of the cranial lamina and the base of the spinous process of the ipsilateral side were removed by the endoscopic burr; c undercutting of the contralateral cranial lamina was performed; d the ipsilateral and contralateral ligamentum flavum was identified and removed piecemeal with endoscopic punches and forceps; e the ipsilateral medial facetectomy was performed to decompress the lateral recess and foramen, ensuring adequate decompression of the traversing nerve root (f) the contralateral medial facetectomy was performed to decompress the lateral recess and foramen, ensuring adequate decompression of the traversing nerve root