Effect of Sagittal Spinal Balance on the Outcome of Decompression Surgery for Lumbar Canal Stenosis

Objective Although sagittal spinal balance is known to affect the outcome of spinal deformity surgery, its effect on simple decompression surgery is not well understood. Materials and Methods Patients who underwent unilateral laminotomy for bilateral decompression for lumbar canal stenosis were prospectively enrolled in the study. Before surgery and 6 months after surgery, the following sagittal-alignment parameters were measured: lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), and sagittal vertical axis (SVA). At the same time, short-form 36 (SF-36) and Visual Analogue Scale (VAS) were estimated. The patients were divided into the poor postoperative physical score group ( P_poor ), good postoperative physical score group ( P_good ), poor postoperative VAS group ( V_poor ), or good postoperative VAS group ( V_good ). The postoperative spinopelvic parameters were compared between the physical score and VAS groups, respectively. Finally, we examined the correlation between the spinopelvic parameters and the outcome scores using scatter plots and linear regression analysis. Results Fifty-two patients were enrolled into the study. Although the spinopelvic parameters (LL, PT, PI-LL) significantly improved after surgery, the absolute values of improvement were relatively small. The postoperative spinopelvic parameters were significantly worse in the P_poor and the V_poor groups compared with the P_good and the V_good groups, respectively. The correlation analyses also showed that worse postoperative spinopelvic parameters correlated to worse outcome in SF-36 and VAS. Conclusions Sagittal spinal balance significantly affected the outcome of patients undergoing decompression surgery for lumbar canal stenosis, the knowledge of which may serve better patient management.