Comparison of clinical outcomes following minimally invasive or lumbar endoscopic unilateral laminotomy for bilateral decompression

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Minimally invasive lumbar unilateral tubular laminotomy for bilateral decompression has gradually gained acceptance as a less destabilizing but efficacious and safe alternative to traditional open decompression techniques. The authors have further advanced the principles of minimally invasive surgery (MIS) by utilizing working-channel endoscope–based techniques. Full-endoscopic technique allows for high-resolution off-axis visualization of neural structures within the lateral recess, thereby minimizing the need for facet joint resection. The relative efficacy and safety of MIS and full-endoscopic techniques have not been directly compared.


A retrospective analysis of 95 consecutive patients undergoing either MIS (n = 45) or endoscopic (n = 50) unilateral laminotomies for bilateral decompression in cases of lumbar spinal stenosis was performed. Patient demographics, operative details, clinical outcomes, and complications were reviewed.


The patient cohort consisted of 41 female and 54 male patients whose average age was 62 years. Half of the patients had single-level, one-third had 2-level, and the remaining patients had 3- or 4-level procedures. The surgical time for endoscopic technique was significantly longer per level compared to MIS (161.8 ± 6.8 minutes vs 99.3 ± 4.6 minutes; p < 0.001). Hospital stay for MIS patients was on average 2.4 ± 0.5 days compared to 0.7 ± 0.1 days for endoscopic patients (p = 0.001). At the 1-year follow-up, endoscopic patients had a significantly lower visual analog scale score for leg pain than MIS patients (1.3 ± 0.3 vs 3.0 ± 0.5; p < 0.01). Moreover, the back pain disability index score was significantly lower in the endoscopic cohort than in the MIS cohort (20.7 ± 3.4 vs 35.9 ± 4.1; p < 0.01). Two patients in the MIS group (epidural hematoma) and one patient in the endoscopic group (disc herniation) required a return to the operating room acutely after surgery (< 14 days).


Lumbar endoscopic unilateral laminotomy for bilateral decompression is a safe and effective surgical procedure with favorable complication profile and patient outcomes.

ABBREVIATIONS AP = anteroposterior; BMI = body mass index; MCID = minimally clinically important difference; MIS = minimally invasive surgery; ODI = Oswestry Disability Index; SAP = superior articular process; ULBD = unilateral laminotomy for bilateral decompression; VAS = visual analog scale.

Article Information

Correspondence Christoph Hofstetter: University of Washington, Seattle, WA.

INCLUDE WHEN CITING Published online January 11, 2019; DOI: 10.3171/2018.9.SPINE18689.

Disclosures Dr. Hofstetter reports being a consultant for J&J, Globus, and Joimax.

© AANS, except where prohibited by US copyright law.



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    AP fluoroscopic intraoperative images for approach planning. A: First, an AP endplate view of the superior endplate of the caudal level is obtained (L3–4, arrow). B: The addition of kyphosis of the rostrocaudal radiographic beam angle moves the projection of the interspinous process space toward the disc space (arrowhead). C: An ideal rostrocaudal trajectory has been determined (arrowhead). D: The skin incision is marked at the tip of the radiopaque object. E: A lateral radiograph may be obtained to confirm the level. F: Once the working tube is brought into place, an AP radiograph confirms the location of the working tube at the inferior margin of the lamina (arrow).

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    As an initial anatomical landmark, the inferior edge of the lamina (lam) is exposed (A). Often the yellow ligament (y) can be seen, too. Following resection of the inferior edge of the lamina with a diamond burr (B), the bony insertion of the yellow ligament can be clearly identified (C). C = caudal; R = rostral; s = base of the spinous process.

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    Entering the epidural space. Using a micropunch, the yellow ligament is opened (A). Following opening of the yellow ligament, ample epidural space and epidural fat is noted. Arrow points to the edge of new opening in yellow ligament with dural interface below (B). The opening is widened using Kerrison rongeurs (C).

  • View in gallery

    Following undercutting of the spinous process, the contralateral inferior articular process (IAP) and SAP forming the posterior wall of the lateral recess become visible (A). Following decompression of the medial aspect of the SAP, the contralateral pedicle (p) and traversing nerve root (arrow) can be inspected (B). C = caudal; R = rostral.

  • View in gallery

    Decompression of the traversing nerve root (arrow) within the ipsilateral lateral recess is carried out using a high-speed drill and Kerrison rongeur (A). Inspection of the undercut ipsilateral facet joint. The medial aspect of the IAP has been resected, and the SAP has been undercut from the tip to the midportion of the caudal pedicle (B). Following decompression, direct visualization of the ipsilateral traversing nerve root is achieved (C).



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