A Nomogram to Predict the Occurrence and Development of Postoperative Neck Tilt in Lenke I and II AIS Patients

To investigate the risk factors and to construct a nomogram for the prediction of postoperative neck tilt (PNT) in Lenke I and II adolescent idiopathic scoliosis (AIS) patients.A total of 95 Lenke I and II AIS patients who underwent posterior segmental spinal instrumentation and fusion between the years 2010 and 2018 (with an average 2-year follow-up) at a single institution were retrospectively investigated. The full spine X-rays of patients were measured preoperatively, postoperatively and at the final follow-up. Variables were compared between the PNT (n = 33) group and the non-PNT group (n = 62), and univariate and multivariate logistic regressions were performed to identify the independent predictors for the occurrence of PNT. The discrimination and calibration of the nomogram were validated by receiver operating characteristic (ROC) curve and calibration curve.Variables including the preoperative neck tilt, postoperative upper instrumented vertebrae (UIV) imbalance, postoperative T1 tilt and decrease values in main thoracic curve (ΔMTC) minus decrease values in proximal thoracic curve (ΔPTC) (ΔMTC - ΔPTC) were identified as the predictors for nomogram. The area under the ROC curve (AUC) was 0.900 (95% CI, 0.857 to 0.932). Meanwhile, the calibration curve revealed good agreement, and the Hosmer and Lemeshow test determined that the model was well fitted.Preoperative neck tilt, postoperative UIV imbalance, postoperative T1 tilt and ΔMTC - ΔPTC are predictors for the nomogram. The nomogram can provide surgeons with a simple and effective tool to predict the occurrence and development of PNT in Lenke I and II AIS patients.