Reoperation Rates Following Thoracolumbar Fusion to the Upper Thoracic versus Lower Thoracic Spine

Introduction: A critical aspect of adult spinal deformity (ASD) surgery is selection of the upper instrumented vertebra (UIV) in the lower thoracic (LT) or upper thoracic (UT) spine. This study compares reoperation rates among patients fused to the UT and LT spine, and explores the impact of demographic factors and comorbidities on reoperation rates.

Methods: A retrospective analysis was conducted using PearlDiver, a national insurance claims database. ASD patients who underwent thoracolumbar fusion with pelvic fixation spanning at least 7 segments were included. The primary outcome was reoperation rates at 1-, 2-, and 5-years after surgery. Demographic and clinical data were analyzed using logistic regression and Kaplan-Meier analysis.

Results: 7,300 patients were included, 6,124 undergoing 7-12 segments of instrumentation and 1,176 undergoing 13+ segments. Unmatched analysis revealed significantly greater osteoporosis (18.8% vs 13.3%, p< 0.001) and osteopenia (27.0% vs 20.9%, p< 0.001) in the 13+ segment group. Curve morphology significantly differed on unmatched analysis, with the 13+ segment group demonstrating greater rates of scoliosis, kyphosis, and sagittal plane deformity. 1,396 patients were included in a 1:1 matched analysis. Overall reoperation rate in matched cohorts were 22.1% and 22.9% for 7-12 segments and 13+ segments, respectively (p=0.70). No significant difference was found in reoperation rates at 1-, 2-, and 5- years in unmatched and matched cohorts. Kaplan-Meier analysis revealed similar reoperation-free probabilities between both cohorts.

Conclusion : This study found no significant difference in reoperation rates between patients with 7-12 and 13+ segments of spinal instrumentation in both unmatched and matched cohorts. Kaplan-Meier survival analysis supports these findings. Further research is needed to explore other factors and surgical techniques contributing to reoperation rates and long-term outcomes.