ObjectiveTo compare the effectiveness and changes of sagittal spino-pelvic parameters between minimally invasive transforaminal lumbar interbody fusion and conventional open posterior lumbar interbody fusion in treatment of the low-degree isthmic lumbar spondylolisthesis. MethodsBetween May 2012 and May 2013, 86 patients with single segmental isthmic lumbar spondylolisthesis (Meyerding degree Ⅰ or Ⅱ) were treated by minimally invasive transforaminal lumbar interbody fusion (minimally invasive group) in 39 cases, and by open posterior lumbar interbody fusion in 47 cases (open group). There was no significant difference in gender, age, disease duration, degree of lumbar spondylolisthesis, preoperative visual analogue scale (VAS) score, and Oswestry disability index (ODI) between 2 groups (P>0.05). The following sagittal spino-pelvic parameters were compared between 2 groups before and after operation: the percentage of slipping (PS), intervertebral height, angle of slip (AS), thoracolumbar junction (TLJ), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), spino-sacral angle (SSA), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). Pearson correlation analysis of the changes between pre- and post-operation was done. ResultsPrimary healing of incision was obtained in all patients of 2 groups. The postoperative hospital stay of minimally invasive group [(5.1±1.6) days] was significantly shorter than that of open group [(7.2±2.1) days] (t=2.593, P=0.017). The patients were followed up 11-20 months (mean, 15 months). The reduction rate was 68.53%±20.52% in minimally invasive group, and was 64.21%±30.21% in open group, showing no significant difference (t=0.725, P=0.093). The back and leg pain VAS scores, and ODI at 3 months after operation were significantly reduced when compared with preoperative ones (P<0.05), but no significant difference was found between 2 groups (P>0.05). The postoperative other sagittal spino-pelvic parameters were significantly improved (P<0.05) except PI (P>0.05), but there was no significant difference between 2 groups (P>0.05). The correlation analysis showed that ODI value was related to the SVA, SSA, PT, and LL (P<0.05). ConclusionBoth minimally invasive transforaminal lumbar interbody fusion and conventional open posterior lumbar interbody fusion can significantly improve the sagittal spino-pelvic parameters in the treatment of low-degree isthmic lumbar spondylolisthesis. The reconstruction of SVA, SSA, PT, and LL are related to the quality of life.