Stereotactic Navigation-Guided Biportal Endoscopic Transforaminal Lumbar Interbody Fusion for Degenerative Lumbar Spondylolisthesis.

Background: In spine surgery, biportal endoscopy (BE) is a minimally invasive approach for addressing a range of degenerative lumbar pathologies, including degenerative lumbar spondylolisthesis. The biportal technique benefits from the separation of the endoscopic viewing portal and the working portal for surgical tools, which facilitates an expanded visual field and greater operative flexibility1-3. BE enables both decompression and transforaminal lumbar interbody fusion (TLIF) within a single procedure4. Furthermore, integrating stereotactic navigation with BE enhances the precision of pedicle screw placement, decompression, intervertebral disc removal, end-plate preparation, and navigated cage insertion.5,6. Description: After positioning the patient prone on a radiolucent table, the surgical field is prepared and draped in a sterile fashion. A reference pin is inserted into the iliac crest to facilitate stereotactic navigation. With use of this navigation, 2 separate 1.5 to 2-cm stab incisions are made just lateral to the cranial and caudal pedicles. The pedicles are probed and tapped in order to allow later pedicle screw fixation. Two additional skin incisions are made on the contralateral side, and percutaneous pedicle screw fixation is performed. A 30° arthroscope is introduced through the cranial incision, and a working portal is established through the caudal incision with use of a semitubular retractor. Irrigation is performed, typically set at 30 mmHg. Radiofrequency ablation is utilized to create a working space and to detach the paraspinal muscles from the underlying lamina, extending caudally into the interlaminar space and laterally to remove the facet joint capsule. Ipsilateral laminotomy or laminectomy is performed with a standard arthroscopic shaver and burr until the cranial insertion of the ligamentum flavum is visualized. Contralateral decompression is achieved by removing the ventral portion of the lamina above the ligamentum flavum, after which the ligamentum flavum is detached and removed. The ipsilateral facet joint is then removed with use of a burr and Kerrison rongeurs until the exiting nerve root is visualized and protected. An anulotomy is performed to access the disc space. End-plate preparation is conducted with use of stereotactic navigation and direct visualization through the endoscope. After trialing, an expandable cage is placed under direct visualization and navigation guidance. The endoscope is utilized to confirm the proper placement of the cage and to coagulate any epidural bleeding. Ipsilateral pedicle screws are placed with use of navigation, and rods are introduced under the fascia. Set screws are applied, and fluoroscopic images are obtained to verify the correct placement of implants. Alternatives: Surgical alternatives for degenerative lumbar spondylolisthesis include both open and tubular decompression, with or without fusion. Potential fusion techniques comprise open posterolateral fusion, open TLIF, microscopic tubular TLIF, anterior lumbar interbody fusion, and lateral lumbar interbody fusion. Rationale: BE TLIF is a minimally invasive procedure that limits osseous and soft-tissue damage and reduces postoperative pain and length of hospital stay compared with traditional open TLIF7-9. Multiple studies have demonstrated similar fusion rates with improved early visual analogue pain and Short Form-36 scores and decreased estimated blood loss for BE TLIF compared with microscopic tubular TLIF10-12. From a technical perspective, BE allows ultra-high magnification, which can assist with adequately decompressing the neural structures and providing direct visualization of end-plate preparation. BE also provides better ergonomics during surgery, as the surgeon is able to stand in a relaxed posture with the head upright and looking straight forward. Expected Outcomes: Long-term outcomes are similar between BE TLIF and microscopic tubular TLIF. However, Luan et al. reported that BE TLIF for lumbar degenerative diseases had the advantages of less intraoperative blood loss, less early postoperative low-back and leg pain, shorter length of hospital stay, and faster early functional recovery13. Important Tips: Gain experience with >50 biportal endoscopic decompression surgeries.Ensure proficiency in managing potential complications such as dural tears and postoperative epidural hematomas before starting TLIF surgery.Understand the stereotactic navigation systems to recognize and address discrepancies between on-screen guidance and actual cage insertion. Acronyms and Abbreviations: BE-TLIF = biportal endoscopic transforaminal lumbar interbody fusionMT-TLIF = microtubular transforaminal lumbar interbody fusionPSIS = posterior superior iliac spineSAP = superior articular processRFA = radiofrequency ablation.