Incidence and Risk Factors of Lumbosacral Complications Following Long-Segment Spinal Fusion in Adult Degenerative Scoliosis.

PURPOSE

Long-segment spinal fusions are associated with lumbosacral complications (LSC), but the associated risk factors are not known. This study aimed to identify the risk factors for LSC after long-segment instrumented fusion with distal fixation to the L5 vertebral body in adult degenerative scoliosis (ADS).

METHODS

We retrospectively evaluated 294 patients with ADS who underwent long-segment floating fusion between January 2014 and March 2022, with follow-up for at least 2 years. Patients were matched to the baseline data using fusion level > 5 as a grouping variable. Patients who completed matching were divided into two groups according to the presence or absence of LSC. Univariate logistic regression was applied to identify potential risk factors for LSC, and multivariate logistic regression was used to identify independent risk factors for postoperative LSC.

RESULTS

The overall incidence of LSC was 21.77% in the 294 patients, with disc degeneration in 28 (9.52%) and radiographic ASD in 44 (14.97%) patients. The mean time to LSC development after surgery was 26.91 ± 8.43 months. A total of 54 pairs of patients were matched and grouped, and the complication group had higher Oswestry Disability Index (ODI) and visual analog scale (VAS) scores at the last follow-up. Multivariate analysis showed that gender (OR = 0.274, p = 0.026 [0.087, 0.859]); levels of fusion > 5 (OR = 3.127, p = 0.029 [1.120, 8.730]), main curve correction rate (OR = 0.009, p = 0.005 [0.000, 0.330]), and postoperative pelvic incidence minus lumbar lordosis (PI-LL) > 15° (OR = 3.346, p = 0.022 [1.195, 9.373]) were independent risk factors for postoperative LSC. The area under the curve value of the prediction model was 0.804, with a 95% confidence interval of 0.715-0.892, indicating that the model had a high prediction accuracy. Collinearity statistics showed no collinearity between variables.

CONCLUSION

Sex, level of fusion > 5, main curve correction rate, and postoperative PI-LL > 15° were independent risk factors for the development of LSC after long-segment floating fusion. These results will improve our ability to predict personal risk conditions and provide better medical optimisation for surgery.