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 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.