Difference of Sagittal Spinopelvic Alignments between Degenerative Spondylolisthesis and Isthmic Spondylolisthesis

OBJECTIVE The purpose of this study was to analyze the differences of spinopelvic parameters between degenerative spondylolisthesis (DSPL) and isthmic spondylolisthesis (ISPL) patients. METHODS Thirty-four patients with DSPL and 19 patients with ISPL were included in this study. Spinopelvic parameters were evaluated on whole spine X-rays in a standing position. The following spinopelvic parameters were measured : pelvic incidence (PI), sacral slope, pelvic tilt (PT), lumbar lordosis (LL), and sagittal vertical axis from C7 plumb line (SVA). The population of patients was compared with a control population of 30 normal and asymptomatic adults. RESULTS There were statistically significant differences in LL (p=0.004) and SVA (p=0.005) between the DSPL and ISPL group. The LL of DSPL (42±13°) was significantly lower than that of the control group (48±11°; p=0.029), but that of ISPL (55±6°) was significantly greater than a control group (p=0.004). The SVA of DSPL (55±49 mm) was greater than that of a control group (<40 mm), but that of ISPL (21±22 mm) was within 40 mm as that of a control group. The PT of DSPL (24±7°) and ISPL (21±7°) was significantly greater than that of a control group (11±6°; p=0.000). CONCLUSION Both symptomatic DSPL and ISPL patients had a greater PI than that of the asymptomatic control group. In conclusion, DSPL populations are likely to have global sagittal imbalance (high SVA) compared with ISPL populations because of the difference of lumbar lordosis between two groups.