Figure 1

Operative image of the three techniques. (a) An image of the operating field applying the retractor after muscle dissection in an open laminectomy, as well as an image of intraoperative level confirmation and a decompressed condition. (b) Appearance of a mounted single portal and the C-arm picture used to examine the surgical level in a full-endoscopic procedure. Endoscopic view of a decompression procedure in uniportal process. (c) Two portals mounted in biportal endoscopic surgery. The C-arm image demonstrated level confirmation and docking of instruments. Endoscopic view of biportal process.