Upper Instrumented Vertebrae Distal to T2 Leads to a Higher Incidence of Proximal Junctional Kyphosis During Growing-rod Treatment for Early Onset Scoliosis

Abstract

STUDY DESIGN: A retrospective case series. OBJECTIVE: We sought to evaluate the prevalence and risk factors of proximal junctional kyphosis (PJK) after growing-rod surgery in patients with early onset scoliosis (EOS). SUMMARY OF BACKGROUND DATA: Growing-rod surgery is the primary treatment in patients with progressive EOS when conservative treatment fails. PJK is one of the most commonly reported postoperative complications. MATERIALS AND METHODS: We retrospectively evaluated 50 patients (24 boys and 26 girls) diagnosed with EOS who underwent growing-rod surgery. Preoperative and follow-up demographic data, surgical strategies, and radiographic parameters were recorded and analyzed to identify PJK risk factors. RESULTS: The mean age of patients at the time of the initial surgery was 8.6±2.5 years. Mean follow-up was 33.5±10.8 months, and mean number of lengthening surgeries were 2.14±1.52. Twenty-eight of the surgical procedures were single growing-rod surgeries, of which 22 were dual growing-rod surgeries. The upper instrumented vertebrae (UIV) ranged from C6-T6, and the lower instrumented vertebrae ranged from L1-S1. Ultimately, PJK developed in 14 (28%) of 50 patients. Taller patients, UIV distal to T2, and greater postoperative upper thoracic scoliosis (UTS) were suspected potential risk factors of PJK during the univariate analysis (P<0.1). Multifactorial regression analysis confirmed that UIV distal to T2 (hazard ratio=5.474; P=0.044) and postoperative UTS >50 degrees (hazard ratio=1.049; P=0.046) were the independent risk factors of PJK during growing-rod treatment in patients with EOS. CONCLUSIONS: The prevalence of PJK was 28% during growing-rod treatment in EOS. The independent risk factors for PJK were UIV distal to T2 and postoperative UTS >50 degrees. It is important for spine surgeons to recognize these risk factors when planning surgeries, and counseling patients and families about this possible complication. LEVEL OF EVIDENCE: Level III.