What question did this study set out to answer?

This research investigates the anatomical considerations crucial for biportal endoscopic spine surgery success.

February 2, 2026Journal of Minimally Invasive Spine Surgery and Technique1 citationsOpen Access

Endoscopic Anatomy of the Lumbar Spine: Implications for Advancements in Biportal Endoscopic Spine Surgery

ARAjid RisdiantoDiponegoro University HKHappy KurniaDr. Kariadi Hospital MIM. Farhan IsmailUniversitas Gadjah Mada

Key Points

This research investigates the anatomical considerations crucial for biportal endoscopic spine surgery success.
Conducted a retrospective, video-based analysis of 23 BESS lumbar decompression cases
Evaluated intraoperative anatomical landmarks identified by two spine surgeons
Measured cranial and caudal interlaminar-disc mismatches and scored visualization quality
93% of cases showed interlaminar-disc mismatch with cranial and caudal mismatches from 5.5±1.02 mm to 8±1.2 mm
Observed consistent laminar curvature at the L4–5 and L5–S1 levels
Identified superior articular process as a reliable surgical landmark
Achieved high interobserver reliability with κ=0.84 for anatomical identification

Abstract

Objective: Biportal endoscopic spine surgery (BESS) has emerged as a minimally invasive alternative for lumbar decompression, offering improved visualization with reduced tissue disruption. Therefore, this study aims to identify key anatomical considerations, particularly interlaminar-disc mismatch and the “banana-shaped” curvature of the lamina, and to examine their impact on portal trajectory, alignment of the surgical corridor, and preservation of spinal structures.Methods: A retrospective, video-based analysis was conducted on 23 BESS lumbar decompression cases performed between January and March 2024. Surgical levels included L3–4 (n=3), L4–5 (n=17), and L5–S1 (n=3). Intraoperative anatomical landmarks were assessed independently by 2 spine surgeons. Interobserver agreement was evaluated using Cohen kappa, based on the identification of 3 landmarks per case in 23 cases, calculated with unweighted kappa. Visualization quality was scored on a 3-point scale. Cranial and caudal interlaminar-disc mismatches were measured and averaged.Results: Interlaminar-disc mismatch was identified in 93% of cases, with cranial and caudal mismatches ranging from 5.5±1.02 mm to 8±1.2 mm. Laminar curvature was consistently observed at L4–5 and L5–S1, which required a medial-caudal portal. In addition, the superior articular process (SAP) served as a reliable fluoroscopic and endoscopic landmark, facilitating safe access to the intervertebral disc. A limited medial facetectomy provided adequate operating space. The findings also demonstrated high interobserver reliability for anatomical identification (κ=0.84), and the use of layer-specific flavectomy preserved the inner layer of the ligamentum flavum.Conclusion: Successful BESS requires integrating detailed anatomical understanding with intraoperative adaptability. Recognizing interlaminar-disc mismatch, laminar curvature, and SAP orientation enables optimal portal placement and targeted decompression. These principles are essential for achieving reproducible and safe outcomes in BESS.

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