Surgically Relevant Morphological Parameters of the L5-S1 Interlaminar Window: A Statistical Analysis Based on 3D Reconstruction of CT Data.

Abstract

The interlaminar window is the most important anatomical corridor during the posterior approach for lumbar and lumbosacral pathologies. Three-dimensional (3D) reconstruction of the L5-S1 interlaminar window including accurate measurements may be beneficial for the surgeon. The aim of this study was to measure relevant surgical parameters of the L5-S1 interlaminar window based on 3D reconstruction of lumbar computed tomography (CT). Fifty thin-layer CT data were retrospectively collected, segmented, and reconstructed. Relevant surgical parameters included the width, left height, right height, interpedicular distance (IPD), area, and suitable approach area of the L5-S1 interlaminar window. Morphological measurements were performed independently by two experienced experts. Patients with disk herniation at L5-S1 were regarded as group A (n = 28) and those without L5-S1 disk herniation were regarded as group B (n = 22). The average left height, right height, width, and area of the L5-S1 interlaminar window were 9.14 ± 2.45 mm, 9.55 ± 2.46 mm, 23.55 ± 4.91 mm, and 144.57 ± 57.05 mm2, respectively. The average IPD at the superior, middle, and inferior pedicle levels was 29.29 ± 3.39, 27.96 ± 3.38, and 37.46 ± 4.23 mm, respectively, with significant differences among these three parameters (p < 0.05). The average suitable approach areas of the L5-S1 interlaminar window were the following: left axilla-24.52 ± 15.91 mm2; left shoulder-27.14 ± 15.48 mm2; right axilla-29.95 ± 17.17 mm2; and right shoulder-31.12 ± 16.40 mm2 (p > 0.05). There were no significant differences between groups A and B in these parameters (p > 0.05), except the inferior IPD (36.69 ± 3.73 vs. 39.23 ± 3.01 mm, p = 0.017 < 0.05). The morphological measurement of the L5-S1 interlaminar window based on 3D reconstruction provided accurate and reliable reference data for posterior microsurgical and endoscopic approaches as well as percutaneous infiltrations.