259. Under-contoured proximal rod: a potential risk factor of PJK in Scheuermann's kyphosis

Abstract

BACKGROUND CONTEXT Correction of kyphosis in Scheuermann's Kyphosis (SK) patients can be effectively achieved via a multilevel Ponte osteotomies pedicle screw-based instrumentation. However, the risk of developing proximal junctional kyphosis remains an important issue after surgeries for SK. The influence of the proximal rod contouring on the occurrence of PJK has not been investigated in SK patients. PURPOSE The aim of this study was to evaluate the influence of the proximal rod contouring on the radiographic results in patients with Scheuermann's Kyphosis. STUDY DESIGN/SETTING Single-center retrospective study. PATIENT SAMPLE This study included 59 patients with SK (57 men, 2 women), who had undergone posterior correction surgery between 2002 and 2015, and had been followed at least 12 months. OUTCOME MEASURES The proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to UIV (UIV-2). A PJK was defined by the presence of a proximal junctional angle (PJA) greater than 10° at the latest follow-up, and the increase of this angle by more than 10° compared with preoperatively. METHODS Patients were separated into 2 groups: PJK group and non-PJK group. Comparisons were performed in terms of T-test between these two groups. ROC curve analysis and logistic regression analysis were performed. RESULTS The mean age was 20.24 ± 9.47 years old and the follow-up average were 16.3 months ± 8.3. No significant difference was found between two groups with regards to their ages, the PJA and the PCRA at preoperative time. At the last follow-up, 31,7% of the patients developed PJK, the mean value of PJA was 19.21 ± 4.6 in PJK group and was 7.76 ± 3.72 in non-PJK group (p CONCLUSIONS Patients whose PCRA angle are lower than 10° after surgery are more likely to develop PJK, demonstrating that under-contouring of the proximal rod is a risk factor for PJK in SK. So, proximal portion of the rod should be bent more kyphotic (more than 10° ). FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.