Mechanical complications and reoperations after adult spinal deformity surgery: a clinical analysis with the GAP score

Abstract

Abstract Purpose Adult spinal deformity (ASD) surgery is prone to postoperative complications, leading to high reoperation rates. The global alignment and proportion (GAP) score is a novel method to predict mechanical complications (MC) based on the optimal parameters related to individual pelvic incidence. The aim of this study was to determine the cut-off point and the predictive value of the GAP score for those MCs that require reoperation. A secondary aim was to investigate the cumulative incidence of MCs requiring reoperation during a long follow-up period. Methods In total, 144 ASD patients were operated at our institution due to marked symptomatic spinal deformity between 2008 and 2020. The cut-off point and the predictive value of the GAP score for the MCs that required reoperation and the cumulative incidence of reoperated MCs after index surgery were determined. Results A total of 142 patients were included in the analysis. The risk for having an MC that required reoperation was significantly lower when the postoperative GAP score was < 5 (HR = 3.55, 95% CI: 1.40–9.02). The discriminative power of the GAP score to predict MCs that require reoperation was good with an AUC of 0.70 (95% CI: 0.58–0.81). The cumulative incidence of reoperated MCs was 18%. Conclusion The GAP score was associated with the risk for MCs that require reoperation. The best predictive value for surgically treated MC was with the GAP score $$\ge$$ ≥ 5. The cumulative incidence of the reoperated MCs was 18%.