Similar Reoperation Rates in Upper versus Lower Thoracic to Pelvis Instrumentation

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.

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 2-years. Demographic and clinical data were analyzed using standard t-tests and chi-square tests and Kaplan-Meier analysis.

Results: 7,300 patients were included, 6,124 undergoing 7-12 segments of instrumentation (lower thoracic, LT) and 1,176 undergoing 13+ segments (upper thoracic, UT). 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 UT group. Curve morphology significantly differed on unmatched analysis, with the UT group demonstrating greater rates of scoliosis, kyphosis, and sagittal plane deformity. 698 patients were included in each cohort in a 1:1 matched analysis. Overall reoperation rate in matched cohorts were 22.1% and 22.9% for the LT and UT cohorts respectively (p=0.70). No significant difference was found in reoperation rates at 2-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 fused to the LT and UT spine. Kaplan-Meier survival analysis supports these findings.