Risk Factors of Revision Surgery After Acute Proximal Junctional Fracture Following Adult Spinal Deformity Surgery

BACKGROUND AND OBJECTIVES: Acute proximal junctional fracture (APJFx) is a severe form of proximal junctional kyphosis after adult spinal deformity surgery and is often associated with revision surgery. However, the clinical course of APJFx is heterogeneous, and not all patients require revision. The aim of this study was to identify independent risk factors of revision surgery after APJFx to guide the timing and necessity of revision surgery. METHODS: This retrospective study included patients who developed APJFx within 6 months after undergoing multilevel (≥5 levels) fusion surgery. Demographic, surgical, and radiographic variables were analyzed. Initial postoperative alignment was evaluated using the sagittal age-adjusted score and the Global Alignment Proportion score. Radiographic parameters at the time of APJFx detection were also assessed. Revision-free survival was analyzed using Kaplan-Meier analysis. Independent predictors of revision surgery were identified through multivariate logistic regression, and optimal cutoff values were determined using receiver operating characteristic analysis. Patients were stratified into 4 subgroups based on identified risk factors. RESULTS: Eighty patients met the inclusion criteria, and 35 patients (43.8%) underwent revision surgery during a mean follow-up of 24.6 months. Most revision surgeries (82.9%) were performed within 24 months after APJFx detection. Multivariate analysis identified 2 independent predictors of revision surgery: a higher sagittal age-adjusted score pelvic incidence minus lumbar lordosis (PI-LL) modifier score (odds ratio = 1.76; cutoff = 0.5 point, indicating PI-LL overcorrection) and a greater proximal junctional angle at APJFx detection (odds ratio = 1.10, cutoff = 22.5°). Patients with both risk factors exhibited the highest revision rate (71.4%), whereas those with neither risk factor had the lowest rate (17.6%). CONCLUSION: Revision surgery after APJFx is common, particularly in patients with PI-LL overcorrection and increased proximal junctional angle at fracture detection. Risk-based stratification using these parameters may aid in guiding early surgical decision making and surveillance strategies.