2024 Volume 15 Issue 9 Pages 1195-1201
Introduction: In thoracolumbar/lumbar (TL/L) curve of Lenke types 1B and 1C, poor Cobb-angle correction is sometimes observed on the X-ray images after selective thoracic fusion, even when the hump shows good improvement. Our objective was to evaluate the relationship between postoperative improvement in the angle of trunk rotation (ATR) and Cobb angle of the TL/L curve.
Methods: Sixteen subjects (1 male and 15 females; mean age, 15.8 years) who underwent selective thoracic fusion for Lenke type 1B and 1C curves between 2009 and 2015 were followed up for ≥2 years. Improvement was analyzed for the correlation between the ATR measured by a scoliometer and Cobb angle measured on plain X-ray images preoperatively and at 2 years postoperatively. Cobb-angle improvement was predicted by regression analysis based on ATR improvement; Cobb-angle improvement was classified as poor or good when the actual improvement was less than or equal to the predicted value. Factors related to Cobb-angle improvement in the perioperative period were identified using logistic regression analysis.
Results: Moderate positive correlation was observed between the improvement in ATR and Cobb angle for TL/L curves at 2 years postoperatively (Pearson correlation coefficient 0.54, p = 0.02). Poor or good improvement in the Cobb angle was observed in eight cases each. The only perioperative factor that altered the effect of ATR improvement on Cobb-angle improvement was preoperative L4 tilt (odds ratio 0.58, p = 0.05). Significant effects were not observed for factors including body mass index, ATR or Cobb-angle improvement of the main thoracic curve, flexibility or apical vertebral translation of the preoperative TL/L curve, lumbar spine modifier, and thoracolumbar kyphotic angle. No domain of the Scoliosis Research Society questionnaire differed significantly between poor and good Cobb-angle improvements at 2 years.
Conclusions: ATR and Cobb-angle improvement in compensatory TL/L curves showed a correlation, and larger preoperative L4 tilt was related to better ATR but not Cobb-angle improvement. Larger preoperative L4 tilt might have a negative influence on the correction of frontal-plane curves but not on rotational deformity. Further investigation with a larger numbers of subjects is required.
