Coronal Plane Imbalance in Adolescent Idiopathic Scoliosis With Left Lumbar Curves Exceeding 40°

STUDY DESIGN: Retrospective radiographic analysis of the potential role the lumbosacral hemicurve has on adolescent idiopathic scoliosis coronal trunk imbalance. OBJECTIVE: To determine if the lumbosacral hemicurve predisposes adolescent idiopathic scoliosis to coronal decompensation preoperatively and postoperatively. SUMMARY OF BACKGROUND DATA: Although coronal decompensation remains a clinical problem in adolescent idiopathic scoliosis, the literature regarding the role of potential intrinsic structural properties of the lumbosacral hemicurve is sparse. METHODS: Fifty patients with adolescent idiopathic scoliosis were used to measure several potential parameters predisposing to coronal decompensation including lumbosacral hemicurve magnitude and flexibility, sacral and iliac obliquity. RESULTS: Overall, 84% (42/50) demonstrated preoperative decompensation. A more rigid lumbosacral hemicurve was significantly related to preoperative coronal decompensation in the combined and the King I groups. Preoperatively, significant correlation with decompensation was observed for sacral and iliac obliquity in the King I group and for iliac obliquity in the combined group. Postoperatively, coronal decompensation remained significantly correlated to sacral obliquity in the combined group and King I groups. Iliac obliquity was significantly related to postoperative decompensation in the combined group. CONCLUSIONS: The lumbosacral hemicurve represents an important structure predisposing to left coronal plane imbalance in adolescent idiopathic scoliosis that includes a large left lumbar curve as a component of the curve pattern. "At-risk" signs for persistent postoperative coronal decompensation include iliac and sacral obliquity noted on the preoperative standing full-length radiographs.