L1 Slope as an Indicator of Thoracolumbar Sagittal Balance in Osteoporotic Vertebral Fractures

Abstract

Study Design: Feasibility study. Objectives: To evaluate the association between L1 slope and thoracolumbar spinal parameters of sagittal balance in cases of osteoporotic vertebral fracture. Summary of Literature Review: Recently, interest has emerged in the sagittal parameters of the thoracolumbar spine in cases of osteoporotic vertebral fracture. Materials and Methods: Eighty-five patients were enrolled in this study, including 36 patients with recent osteoporotic vertebral fractures (group 1) and 49 patients who did not have vertebral fractures (group 2). Radiographic parameters including L1 slope, C7 plumb line (C7 PL), sagittal imbalance (C7 PL >50 mm), lumbar lordosis, thoracic kyphosis, pelvic tilt, S1 slope, local kyphotic angle were evaluated on standing lateral radiographs of the whole spine. We analyzed correlations between L1 slope and these parameters. Results: Of the sagittal parameters of the spine, the mean L1 slope, C7 PL, thoracic kyphosis, lumbar lordosis, S1 slope, pelvic tilt, and local kyphotic angle were 10.43°, 92.43 mm, 29.30°, 30.31°, 25.27°, 27.27°, 9.90° in group 1 and 9.41°, 68.50 mm, 20.09°, 23.25°, 22.03°, 31.43°, 8.21° in group 2, respectively. There were significant differences in thoracic kyphosis (p=0.01) and lumbar lordosis (p=0.04) between the two groups. L1 slope was positively correlated with thoracic kyphosis (r=0.46, p=0.01), lumbar lordosis (r=0.51, p=0.01), and local kyphotic angle (r=0.29, p=0.04) in group 1. Conclusions: These results suggest that L1 slope is a central indicator for the evaluation of thoracolumbar sagittal balance in osteoporotic vertebral fractures.