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

Abstract Background 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). Methods 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). Results 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). Conclusion 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.