Double Thoracic Curve

For type 2 DT curves, the general rule is to fuse both the PT and MT regions posteriorly. The upper end vertebra of fusion is usually either T2 (left shoulder high before surgery) or T3 (shoulders level, or, rarely, right shoulder high before surgery), and the lower level of fusion is selected again based on the CSL, as noted above for type I MT curves. It is extremely important to assess the radiographic and clinical aspects of the PT curve and clinical shoulder balance preoperatively to obtain and maintain optimal shoulder balance postoperatively. This is especially true with newer instrumentation techniques such as thoracic pedical screws that afford much greater coronal correction of the main thoracic curve.

With increasing translational correction of the main thoracic curve to the midline, the tendency toward elevating the left shoulder when correcting a right main thoracic curve becomes much more difficult to avoid.