Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P91. Lenke 1 adolescent idiopathic scoliosis: effects of TK restoration on regional and global alignment

BACKGROUND CONTEXT While historically the main focus in AIS was the coronal Cobb, there has been a growing interest in also integrating consideration for sagittal plane alignment. The effect of surgical thoracic kyphosis (TK) correction on adjacent curvatures remains unclear. PURPOSE This study aims to elucidate the reciprocal changes associated with TK correction in Lenke one-two AIS patients. STUDY DESIGN/SETTING Multicenter retrospective study. PATIENT SAMPLE A total of 155 AIS patients with Lenke one-two curves operated on with either surgical bands or pedicle screws were included. OUTCOME MEASURES Classic spino-pelvic parameters at baseline and 2years (2Y). METHODS Reciprocal changes associated to TK correction were analyzed, alignment predictive formulas were defined using 75% of the cohort and 25% for validation. RESULTS A total of 155 patients were included (15yo, 86% female), the majority of patients (92.9%) had T4-T12 completely fused. From pre to post, there was a significant decrease (all p CONCLUSIONS It is already known that the correction of one sagittal curve leads to changes in surrounding curves and it is well observed in this study that the correction of TK leads to changes in CL and LL. These changes are directly correlated to the magnitude of TK change, and are thus predictable. It is interesting to note that an inadequate restoration of TK from hypokyphosis will result in a greater PI-LL mismatch.In the setting of surgical planning; these formulas would be invaluable for the surgeons and could lead to better postop courses.