Incidence and Risk Factors of Sacral Fracture Following Lumbosacral Fusion for Degenerative Spinal Stenosis with a Minimum Follow-Up of 2 Years: A Case-Control Study.

Abstract

This study aimed to investigate the incidence and risk factors for sacral fractures following lumbosacral fusion. We conducted a retrospective review of patients who underwent lumbosacral fusion for degenerative spinal stenosis with a minimum follow-up of 2 years. Patients who developed and those who did not develop a sacral fracture were categorized into the "sacral fracture" and "nonfracture" groups. The demographic and radiological data were compared between the 2 groups. A total of 65 patients were included in this study. Among them, 7 patients were categorized into the sacral fracture and 58 patients into the nonfracture groups, respectively. The incidence of sacral fracture was 10.8%. In the sacral fracture group, age and fusion levels were significantly higher (P<0.05), while bone mineral density (BMD) T-score was significantly lower (P<0.05) than nonfracture group. Pelvic incidence, preoperative pelvic tilt, postoperative sacral slope, and postoperative lumbar lordosis were significantly higher (P<0.05) in the sacral fracture than the nonfracture group. Multivariable logistic regression analysis showed that BMD T-score (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.08-0.79, P = 0.019), postoperative sacral slope (OR 1.14, 95% CI 1.00-1.29, P = 0.047), and changes in L4-S1 lordosis (OR 1.11, 95% CI 1.00-1.23, P = 0.049) were significant factors. The overall incidence of sacral fracture was 10.8%. In our study, advanced age, low BMD, long fusion levels, and preoperative compensatory pelvic retroversion and excessive correction of it were risk factors for sacral fractures.