Fig. 2

Intraoperative view. a: Marking the skin incision. b: Resection of interspinous ligament. The epidural fat (black circle) is visible between the L4 lamina (black arrow) and L5 lamina (white arrow). c: Exposure of epidural space. The black asterisk is dura. d: Dural incision reveals the arachnoid (white asterisk). White triangular arrows indicate the sheath edge. e: Limiting deviation of the normal cauda equina nerve roots (white stars) using sheath edge and irrigation. f: The black star is the filum terminale. g: Green rubber sheet inserted under the filum. h: Coagulating of the filum. i: Cutting. j: Part of the filum removed. k: Dural suturing. l: Closed incision