Prediction of Spontaneous Lumbar Curve Correction After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Lenke Type 1 Curves

Study Design: This is a retrospective single-center and single-surgeon study. Objective: The present study examined for preoperative parameters having the highest correlation with compensatory thoracolumbar/lumbar (TL/L) curve correction 2 years after surgery in adolescent idiopathic scoliosis (AIS) patients with Lenke type 1 curves. Summary of Background: Several parameters have been considered to evaluate the flexibility of compensatory TL/L curve in AIS patients with Lenke type 1 curves. However, the imaging position with the strongest correlation with postoperative spontaneous TL/L curve correction is unknown. Data: In total, 37 patients with AIS Lenke type 1 curves who had undergone skip pedicle screw fixation were followed for a 2-year period were enrolled. Materials and Methods: TL/L Cobb angles measured at the standing posteroanterior view, supine position, supine position with maximum bending, supine position with traction, prone position, and prone-push position were determined before surgery. Using TL/L Cobb angles determined 2 years postoperatively, correlations between preoperative and postoperative Cobb angles were calculated for each position using the Spearman rank-correlation coefficient, linear regression analysis, and paired t tests. Results: Mean preoperative mean±SD TL/L Cobb angle was significantly improved from 31±9 to 13±8 degrees at the study end point. In analyses of correlations between postoperative TL/L Cobb angle and preoperative parameters, the supine position with traction was most strongly associated with TL/L curve correction rate at 2 years after surgery (r=0.72; P<0.01), with paired t tests revealing a significant mean difference of 3.1 degrees. Conclusions: Preoperative Cobb angle evaluated at the supine position with traction had the strongest correlation with spontaneously corrected TL/L curve Cobb angle after selective thoracic fusion for AIS Lenke type 1 curves. Accordingly, it may be sufficient to evaluate TL/L curve correction at this position only to reduce radiation exposure and operative time.