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. 2016 Apr;41(8):698-704.
doi: 10.1097/BRS.0000000000001303.

Adding-on Phenomenon After Surgery in Lenke Type 1, 2 Adolescent Idiopathic Scoliosis: Is it Predictable?

Changwei Yang  1 , Yanming Li, Mingyuan Yang, Yunfei Zhao, Xiaodong Zhu, Ming Li, Gabriel Liu
Affiliations

Adding-on Phenomenon After Surgery in Lenke Type 1, 2 Adolescent Idiopathic Scoliosis: Is it Predictable?

Changwei Yang et al. Spine (Phila Pa 1976). 2016 Apr.

Abstract

Study design: A retrospective study.

Objective: The aim of this study was to detect risk factors for Adding-on after posterior correction surgery in patients with Lenke 1 or 2 AIS, and to explore whether Adding-on Index could be used to predict Adding-on effectively.

Summary of background data: Adding-on phenomenon is a common complication in Lenke 1 or 2 AIS patients after correction surgery. However, whether it can be predicted after surgery remains unknown.

Methods: Lenke 1 or 2 AIS patients receiving correction surgery in our center from January 2009 to July 2013 were analyzed. Antero-posterior and lateral films were evaluated before surgery, at 2 weeks' and 2 years' follow-up. Patients were divided into 2 groups according to whether Adding-on occurred at the 2 years' follow-up. Risk factors of Adding-on were analyzed, and Adding-on Index was proposed and verified.

Results: Sixteen patients (16.3%) suffered from distal Adding-on at 2-year follow-up. Several parameters were found to be significantly different between 2 groups, including Risser's sign, postoperative Cobb angle of main thoracic, postoperative Cobb angle of main thoracic curve at 2-year follow-up, preoperative and postoperative Cobb angle of lumbar curve, postoperative Cobb angle of lumbar curve at 2-year follow-up, LIV-EV, LIV-SV, LIV-CSVL, LAV-CSVL, LAV-LIV, DnfS, and postoperative TJK. No significant differences in SRS-22 scores were observed. Binary logistic regression analysis showed that DnfS and postoperative residual Cobb angle of lumbar curve were primary factors for occurrence of Adding-on. According to the regression equation, Adding-on Index was defined as 4 × DnfS-postoperative lumbar curves Cobb angle. On the basis of ROC curve, if Adding-on Index was more than 12, the occurrence rate of Adding-on was 88%. On the contrary, the rate of no Adding-on phenomenon was 80%.

Conclusion: DnfS and posterior Cobb angle of lumbar curve were 2 important factors for Adding-on in Lenke 1, 2 AIS patients. Adding-on Index can be used to predict the occurrence of Adding-on effectively.

Level of evidence: 4.

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