Characteristics of Sciatic Scoliotic List in Lumbar Disc Herniation

Abstract

Study Design Retrospective radiological study. Objectives Physical examination reveals sciatic scoliotic list (SSL) in some patients with lumbar disc herniation (LDH). We aimed to evaluate the coronal and sagittal parameters of the SSL curve, describe their characteristics, and establish a new classification system. Methods We retrospectively reviewed 230 patients (SSL group = 96; non-SSL group = 134) diagnosed with single-segment LDH from January 2018 to December 2020. The control group comprised 70 healthy volunteers. Radiographic parameters were compared between the groups. Results In the SSL group, the Cobb’s angle was 12.5 ± 5.3° (4.2-31.2), trunk shift 26.2 ± 17.9 mm (.0-88.2 mm), and apical vertebral translation 31.7 ± 16.0 mm (1.18-8.58 mm). Further, 62.5% of patients had L4/5 disc herniation, 76.0% had disc herniation at the convex side of the lumbosacral scoliosis, and 81.3% had disc herniation at the opposite side of the trunk shift. Compared to the control group, lumbar lordosis and thoracic kyphosis decreased, pelvic tilt increased, and the sagittal vertical axis moved forward in the other patients. The sagittal imbalance in the SSL group exacerbated. Using the positional relationship between vertebrae and the central sacral vertical line (CSVL), we identified two main SSL patterns with which 95.8% of the patients were defined as Type 1. Conclusions The SSL curve is characterized by a long thoracic or thoracolumbar curve, with a relatively straight sagittal profile and little rotation. Further, the lumbar and thoracic vertebrae shifts are on the same side as the CSVL. These features of the SSL curve differentiate it from other types of structural scoliosis.