Incidence and Risk Factors of PJK in AIS Patients Treated With Patient-Specific Rods

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the incidence and risk factors of proximal junctional kyphosis (PJK) in adolescent idiopathic scoliosis (AIS) patients treated with patient-specific rods, and to assess its clinical impact using the Scoliosis Research Society-22 (SRS-22) score. SUMMARY OF BACKGROUND DATA: PJK is a frequent complication following scoliosis surgery. Patient-specific rods have been introduced to improve mechanical outcomes, but their influence on PJK incidence remains unclear. METHODS: This study included 50 AIS patients who underwent posterior spinal fusion with patient-specific rods, with a minimum follow-up of 18 months. Radiographic parameters and clinical outcomes (SRS-22 scores) were assessed. PJK was defined according to Glattes criteria. Patients were grouped based on the presence or absence of PJK. Demographic, surgical, and radiographic variables were compared using t tests and χ2 tests. Logistic regression analysis was used to identify risk factors. RESULTS: PJK was observed in 10 of 50 patients (20%) at the last follow-up. Among these, 40% developed PJK within 6 weeks postoperatively. No significant differences were found between PJK and non-PJK groups regarding age, BMI, Risser stage, curve type, spinopelvic parameters, or surgical variables (UIV, LIV, number of levels fused). However, a larger immediate postoperative proximal junctional angle (PJA) was significantly associated with PJK development. SRS-22 functional scores did not differ significantly between groups. CONCLUSIONS: The incidence of PJK in AIS patients treated with patient-specific rods was 20%. A larger immediate postoperative PJA was identified as a significant risk factor for PJK. Despite its radiographic presence, PJK did not impact short-term clinical outcomes in this cohort.