An Analysis of the Risk Factors for Adding-on Phenomena After Posterior Hemivertebral Resection and Pedicle Screw Fixation for the Treatment of Congenital Scoliosis Caused by Hemivertebral Malformation

Abstract

Objective To retrospectively analyze the risk factors for adding-on phenomena (AOP) after posterior hemivertebral resection (PHR) and pedicle screw fixation for the treatment of congenital scoliosis (CS) caused by hemivertebral (HV) malformation. Methods Patients with CS who underwent surgery and were followed up for more than five years were included in this study. The d general data, such as gender, age, HV segment, Risser sign, and triangular cartilage, postoperative complications, and imaging data at different periods, including the standard anteroposterior and lateral x-rays of the total spine were collected. Results In total, 58 patients were included in this study, of which 10 experienced AOP and 48 did not. The results of the single-factor analysis showed that there were statistically significant differences between the patients with AOP and those without in terms of the HV direction, lowest instrumented vertebra (LIV)–upper instrumented vertebra (UIV) (P < 0.05), and postoperative trunk shift (P < 0.05). The results of the logistic regression analysis showed that the HV direction and the postoperative trunk displacement distance were the main risk factors for postoperative AOP. The area under the receiver operating characteristic curve was 0.842 (P < 0.001). The best cut-off value of the adding-on index as an indicator of the occurrence of AOP after surgery was 0.67. When the adding-on index was >0.67, the incidence of postoperative AOP was 90.0%, and the non-occurrence rate was 22.9%. Conclusion PHR and pedicle screw fixation is an effective way to treat HV malformation in CS. The HV direction, LIV–UIV, and postoperative TS are risk factors for AOP in patients with CS treated with PHR and pedicle screw fixation. The adding-on index has a high degree of accuracy for the prediction of the occurrence of AOP after PHR and pedicle screw fixation.

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“…For hemivertebraeinduced CS, posterior hemivertebra resection combined with segmental fusion was the most common choice of surgery. Its correction rate varied from 46 to 87% (26)(27)(28)(29)(30)(31)(32)(33)(34)(35). The frequency of complications ranged from 0 to 41% (27, 28,32,33,[35][36][37][38][39][40][41][42] and complications included wound infection, addingon phenomenon, pseudoarticulation formation, postoperative progression of scoliosis, the offset of the internal fixation, and pedicle fractures.…”

“…Its correction rate varied from 46 to 87% (26)(27)(28)(29)(30)(31)(32)(33)(34)(35). The frequency of complications ranged from 0 to 41% (27, 28,32,33,[35][36][37][38][39][40][41][42] and complications included wound infection, addingon phenomenon, pseudoarticulation formation, postoperative progression of scoliosis, the offset of the internal fixation, and pedicle fractures. In our previous study (43), it showed that 14 patients with CS younger than 5 years of age accepted short fixation for posterior hemivertebra resection, which had a mean correction rate of 77.86% and no surgery-related complications.…”