RECOGNITION AND TREATMENT OF THE PROXIMAL THORACIC CURVE IN ADOLESCENT IDIOPATHIC SCOLIOSIS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

Study Design. A retrospective radiographic and clinical review of a co nsecutive series of patients with adolescent idiopathic scoliosis (AIS ) instrumented/fused with Cotrel-Dubousset instrumentation (CDI) was u ndertaken. Objective. The authors determined criteria when the upper t horacic curve should be instrumented/fused in AIS treated with CDI and assessed the results of surgical treatment. Summary of Background Dat a. Failure to recognize and include the upper left thoracic curve in t he instrumentation/fusion of a lower right thoracic idiopathic scolios is may produce shoulder imbalance and coronal decompensation. Patients with an elevated left shoulder clinically or a positive T1 tilt radio graphically usually require instrumentation/fusion of the proximal tho racic curve. However, the upper left thoracic curve may be structural and require inclusion in the instrumentation/fusion when the shoulders clinically are level or even if the right shoulder is elevated preope ratively when using CDI. Methods. The authors compared 27 patients wit h AIS with structural upper thoracic curves that were instrumented wit h CDI to T2 (Group I) to 27 patients with King Type III curves treated with CDI that did not have the upper thoracic curve instrumented/fuse d (Group II). Results. The distinguishing Group I preoperative criteri a indicating a structural upper thoracic curve included a proximal tho racic curve greater than 30-degrees that corrected to no better than 2 0-degrees on sidebending; greater-than-or-equal-to Grade I rotation or greater-than-or-equal-to 1 cm translation present at the apex of this curve; any elevation of the left shoulder or tilt of T1 into the conc avity of the upper thoracic curve; or when the transitional vertebra b etween the two curves is at T6 or below. Conclusions. When these afore mentioned criteria are present and surgical correction with CDI is pla nned, we recommend extending the instrumentation up to T2 to produce l evel shoulders and maintain coronal balance.