Radiological analysis for thoracolumbar disc herniation in spinopelvic sagittal alignment: A retrospective study

A retrospective study aims to explore differences in spinopelvic sagittal alignment between thoracolumbar disc herniation (TLD) and lower lumbar disc herniation (LLD). A total of 185 patients included 26 with TLD and 129 with LLD and 30 asymptomatic volunteers in normal group (NG). Each individual took full spine X-ray to evaluate pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), TK+LL+PI, TK/LL, and sacrum-femoral-pubic symphysis (SFP). The Roussouly classification was used to categorize all subjects according to their sagittal alignment. Spinopelvic parameters and Roussouly classification results were compared between groups. PI (51.0°), SS (30.5°), and LL (42.0°) in the TLD were significantly higher than those in the LLD (47°, 27°, 33°, respectively). However, TK (30.0°), TK/LL (0.75), and TK+LL+PI (40.0°) in the TLD were significantly lower than these in the LLD (33.0°, 1.07, 47.2°, respectively) and the similar trend between TLD and NG (34.3°, 0.93, 48.5°, respectively). But LL (42.0°) in the TLD was significantly higher than in the NG (35°). Roussouly types among 3 groups were marked differences. The LLD had a higher rate (59.7%) of type II lordosis (flat back), and the TLD had a higher rate (61.5%) of type III lordosis than other groups. This study implied that patients with TLD have higher LL, lower TK, TK/LL, and TK+LL+PI than LLD patients. We inferred that high LL combined with low TK may be the prospective factors of TLD.