Preoperative ``cervical axis'' deviation increases the risk of distal adding-on following surgery in Lenke 1 and 2 adolescent idiopathic scoliosis patients

• Main Authors: Chan, Chris Yin Wei, Ch'ng, Pei Ying, Lee, Sin Ying, Chung, Weng Hong, Chiu, Chee Kidd, Kwan, Mun Keong
• Format: Article
• Published: SAGE Publications Ltd 2023
• Subjects: RC Internal medicine; RD Surgery
• Online Access: http://eprints.um.edu.my/39645/

Study Design: Retrospective. Purpose: To evaluate the relationship between shoulder/ neck imbalance with distal adding-on phenomenon and to identify other risk factors in Lenke 1 and 2 (non-AR curves) adolescent idiopathic scoliosis (AIS) patients. Methods: 100 Lenke 1 and 2 AIS patients with lowest instrumented vertebra (LIV) cephalad to or at L1 were recruited. Medial shoulder/ neck balance was represented by T1-tilt and cervical axis (CA). Lateral shoulder balance was represented by clavicle angle (Cla-A) and radiographic shoulder height (RSH). Distal adding-on phenomenon was diagnosed when there was disc wedging below LIV of >5(o) at final follow-up. Predictive factors and odds ratio were derived using univariate and multivariate logistic regression analysis. Results: Mean age of this cohort was 15.9 +/- 4.4 years. Mean follow-up duration was 30.9 +/- 9.6 months. Distal adding-on phenomenon occurred in 19 patients (19.0%). Only Risser grade, preoperative CA and final follow-up lumbar Cobb angle were the independent factors. A positive preoperative CA deviation increased the odds of distal adding-on by 5.4 times (95% CI 1.34-21.51, P = 0.018). The mean immediate postoperative T1-tilt, CA, RSH and Cla-A were comparable between the group with distal adding-on and the group without. Conclusion: Distal adding-on phenomenon occurred in 19.0% of patients. Preoperative ``Cervical Axis'' was an important factor and it increased the risk of distal adding-on by 5.4 times. Other significant predictive factors were Risser grade and lumbar Cobb angle at final follow-up. Immediate postoperative shoulder or neck imbalance was not a significant factor for postoperative distal adding-on phenomenon.