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

Abstract

A retrospective case series. 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). 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. 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. 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. 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 III.