General Preparation
The patients were placed in the prone position on the operating table with radiolucent chest frames. All operations
were performed under general anesthesia. The arthroscopy system (Arthrex, Naples, FL, USA) for general orthopedic joints was used.
Surgical Procedure
The portal was checked under fluoroscopic guidance and marked. A spinal needle was used to accurately locate the
intervertebral space in the lateral view under fluoroscopy. Markings were made at 1 cm above and 1 cm below the
needle, and markings were made below the pedicle in the anteroposterior view. A transverse incision of about 1 cm was made and extended to a size sufficient for the instrument to cross-cut the superficial fascia and allow adequate saline flow. A muscle detacher was used to make room for the water to flow through a portion of the proximal lamina and the interlaminar space. In the left-sided approach, the upper portal was used as the viewing portal and the lower portal was used as the working portal. An arthroscopic irrigation system was used in the BE-TLIF, such that the saline irrigation fluid would drain from the viewing portal
to the working portal. When the drainage flow was poor, a small arthroscopic retractor was used to make the fluid flow more smoothly to ensure adequate visibility and to reduce the swelling of soft tissues.
The surgical technique was performed in much the same way as the MIS-TLIF, using a tubular retractor. In MIS-TLIF, the surgery is performed using a tubular retractor and microscopy. In the case of BE-TLIF, the surgery is performed by making two incisions and using an arthroscopic irrigation system. The burr, a Kerrison punch, and an osteotome were used to perform the ipsilateral laminectomy. Subsequently, the contralateral sublaminar decompression was performed. The unilateral facetectomy was performed using osteotomes to harvest the autologous bone. After the removal of the inferior articular
process, the osteotome and the Kerrison punch were used to remove the superior articular process, creating a space
between the exiting nerve root and the traversing nerve root. After completion of the ipsilateral and contralateral
decompressions and facectomies, the ligamentum flavum covering the dura and the nerve root was removed.
An incision was made on the disc using an Indian knife specialized for endoscopy. A pair of pituitary forceps and
a curette were used to perform the discectomy (Fig. 1). The arthroscope was inserted into the disc space to monitor that area, and the cartilaginous endplate was cleanly removed using a curette, to expose the subchondral bone. Allogenic bone chips and the autologous bone harvested from the lamina and facet were impacted under fluoroscopy using a specialized cannula (Fig. 2). A crescenttype cage was inserted vertically under fluoroscopic and arthroscopic guidance and then transversely positioned
using a cage-specific instrument, with a retractor protecting the exiting and traversing nerve roots (Fig. 3). Two ipsilateral percutaneous pedicle screws were inserted using the two previously used portals. Two percutaneous pedicle screws on the contralateral side were inserted into two new incisions on the contralateral side, and in a manner similar to that previously described for the ipsilateral side, the two screws were connected by the percutaneous insertion of a rod. A drain catheter was then inserted to drain any possible epidural hematoma or small bony debris, and the operation was completed.
Fig. 1. Intraoperative arthroscopic images obtained during biportal endoscopic transforaminal lumbar interbody fusion.
(A) Laminectomy using an osteotome for autologous bone harvest. (B) Ostectomy of the inferior articular process. (C) Re
moval of the foraminal ligament after facetectomy. (D) Disc incision using a biportal endoscopic specialized knife for
discectomy.
Fig. 2. (A) Intraoperative arthroscopic view showing the intervertebral disc space with the cartilaginous endplate completely removed. (B) Intraoperative fluoroscopy. Bone grafting is performed using a specialized funnel in the biportal endoscopic transforaminal lumbar interbody fusion. (C) Intraoperative photograph. Fluoroscopy is used when bone grafting is performed.
Fig. 3. (A, B) Intraoperative photographs. When the cage is inserted, two semitubular retractors are used to protect
the traversing and exiting roots. (C, D) Intraoperative anteroposterior and lateral views of fluoroscopy. The cage is inserted
under the fluoroscopic guidance. (E) The portal locations of three different biportal endoscopic approaches. P: pedicle, IPA:
ipsilateral posterior approach, TLIF: transforaminal lumbar interbody fusion, FLA: far lateral approach.