Coronal plane imbalance in adolescent idiopathic scoliosis with left lumbar curves exceeding 40 degrees - The role of the lumbosacral hemicurve

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 postoper atively. Summary of Background Data. Although coronal decompensation remains a clini cal problem in adolescent idiopathic scoliosis, the literature regarding th e role of potential intrinsic structural properties of the lumbosacral ii h emicurve is sparse. Methods. Fifty patients with adolescent idiopathic scoliosis were used to m easure 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 m ore rigid lumbosacral hemicurve was significantly related to preoperative c oronal decompensation in the combined and the King I groups. Preoperatively , significant correlation with decompensation was observed for sacral and i liac obliquity in the King group and for iliac obliquity in the combined gr oup. Postoperatively, coronal decompensation remained significantly correla ted to sacral obliquity in the combined group and King I groups. Iliac obli quity was significantly related to postoperative decompensation in the comb ined group. Conclusions. The lumbosacral hemicurve represents an important structure predisposing to left coronal plane; imbalance in adolescent idiop athic scoliosis that includes a large left lumbar curve as a component of t he curve pattern. "At-risk" signs for persistent postoperative coronal deco mpensation include iliac and sacral obliquity noted on the preoperative sta nding full-length radiographs.