DOS 2018

DOS Kongressen 2018 · 227 Fulcrum flexibility of the main curve predicts postoperative shoulder imbalance in selective thoracic fusion of adolescent idiopathic scoliosis Søren Ohrt-Nissen, Vijay H. D. Kamath, Dino Samartzis, Keith DK Luk, Jason PY Cheung Dep. of Orthopaedic surgery, Spine Unit, Copenhagen university hospital, Rigshospitalet; Dep. of Orthopaedics and Traumatology, The University of Hong Kong Background: Postoperative shoulder imbalance (PSI) remain a common com- plication after corrective surgery for main thoracic (MT) adolescent idiopathic scoliosis (AIS). However, the criteria for when to extend the fusion proximally and the optimal level of curve correction is not well established. Purpose / Aim of Study: To identify preoperative predictors for PSI after cor- rective surgery of adolescent idiopathic scoliosis (AIS). Materials and Methods: The study included a consecutive surgical cohort of AIS patients undergoing selective thoracic fusion. Preoperative antero-poste- rior, lateral and fulcrum bending radiographs were analysed. Postoperatively, a minimum of two years clinical and imaging follow-up was performed of all pa- tients. PSI was defined as a radiographic shoulder height difference of more than 20 mm. Findings / Results: A total of 80 patients were included and 14 patients (18%) were confirmed with PSI at final follow-up. Flexibility of MT curve was an in- dependent risk factor for PSI (odds ratio (OR)= 3.3 per 10% decrease, 95% confidence interval (CI): 1.6-8.2). 27 patients had a preoperative MT flexibility of <55% (OR=11.5, 95%CI: 2.8-46.2). Postoperative T1 tilt was significantly higher in the PSI group (p<0.001) and a T1 tilt of more than 9° resulted in 7.2 times higher odds of developing PSI (95%CI: 2.0-26.0). Fulcrum bending cor- rection index (FBCI) was significantly higher in the PSI group at final follow-up and 25 patients had a final postoperative MT FBCI above 120% (OR=8.5 (95% CI: 2.3-31.0). Conclusions: A low preoperative curve flexibility is a significant predictor for PSI. The surgical strategy should consider proximal fusion if low-flexibility MT curves and/or less aggressive MT curve correction. Achieving a level T1 should be a main priority during intraoperative correction and may require fusion of the PT curve. 168.