A morphometric analysis of thoracic laminae using 3D reconstruction for guiding unilateral biportal endoscopic surgery.

Abstract

PURPOSE: To establish an anatomical reference for thoracic unilateral biportal endoscopic (UBE) surgery by systematically measuring key laminar parameters and analyzing their variations by sex, age, and spinal level. METHODS: Thoracic CT scans from 200 patients (103 males, 97 females) were retrospectively analyzed. Three-dimensional models were reconstructed in Mimics Medical software to measure six laminar parameters: laminar abduction angle (LAA), laminar slope angle (LSA), minimum laminar height (MLH), distance between the inferior margin of the lamina and attachment of the ligamentum flavum onto the cephalad lamina(DLL), distance between the initial point and the middle of the articular process (DIA), and distance from the inferior margin of the lamina to the inferior border of the vertebral body (DLV). RESULTS: All parameters showed significant intersegmental variation (p < 0.05). LAA was largest at T9 (M: 59.93 ± 4.62°, F: 59.22 ± 3.91°) and smallest at T12 (M: 46.12 ± 4.59°, F: 45.73 ± 4.09°). LSA peaked at T1 (M: 114.56 ± 4.92°, F: 114.48 ± 4.39°) and was lowest at T9 (M: 108.63 ± 3.61°, F: 109.36 ± 3.68°). MLH and DLL were generally larger in males. DIA was minimal at T4 (M: 4.46 ± 1.13 mm, F: 4.28 ± 1.02 mm), approximately 1.5 times the diameter of a 3 mm drill. DLV increased caudally, and ligamentum flavum coverage decreased notably at T11–T12. CONCLUSION: This first systematic analysis of thoracic laminar anatomy for UBE surgery reveals significant sex- and level-related variations, providing essential guidance for preoperative planning and intraoperative technique to improve safety and precision.