Radiological analysis for thoracolumbar disc herniation in spinopelvic sagittal alignment

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.