Radiographic and Clinical Outcomes Following Pedicle Subtraction Osteotomy : Minimum 2-Year Follow-Up Data

Objective : The purpose of this study was to report the results of pedicle subtraction osteotomy (PSO) for fixed sagittal imbalance with a minimum 2-year follow-up. Besides, authors evaluated the effect of adjunctive multi-level posterior column osteotomy (PCO) on achievement of additional lumbar lordosis (LL) during PSO. Methods : A total of 31 consecutive patients undergoing PSO for fixed sagittal imbalance were enrolled and analyzed. Correction angle of osteotomized vertebra (PSO angle) and other radiographic parameters including pelvic incidence (PI), thoracic kyphosis, LL, and sagittal vertical axis (SVA) were evaluated. Clinical outcomes and surgical complications were also assessed. Results : The mean age was 66.0 +/- 9.3 years with a mean follow-up period of 33.2 +/- 10.5 months. The mean number of fused segments was 9.6 +/- 3.5. The mean operative time and surgical bleeding were 475.9 +/- 160.5 minutes and 1406.1 +/- 932.1 mL, respectively. The preoperative SRS-22 score was 2.3 +/- 0.7 and improved to 3.2 +/- 0.8 at the final follow-up. The mean PI was 54.5 +/- 9.5 degrees. LL was changed from 7.0 +/- 28.9 degrees to -50.2 +/- 13.2 degrees. The PSO angle was 33.7 +/- 13.5 degrees (15.6 +/- 20.1 degrees preoperatively, -16.1 +/- 19.4 degrees postoperatively). The difference of correction angle of LL (57.3 degrees) was greater about 23.6 degrees than which of PSO angle (33.7 degrees). SVA was improved from 189.5 +/- 93.0 mm, preoperatively to 12.4 +/- 40.8 mm, postoperatively. There occurred six, eight, and 14 cases of complications at intraoperative, early (<2 weeks) postoperative, and late (>= 2 weeks) postoperative period, respectively. Additional operations were needed in nine patients due to the complications. Conclusion : PSO could provide satisfactory results for patients with fixed sagittal imbalance regarding clinical and radiographic outcomes. Additional correction of LL could be achieved with conduction of adjunctive multi-level PCOs during PSO.