From the material and data reviewed in our study of 405 patients, it
appears that postoperative correction of the thoracic spine approximately
equals the correction noted on preoperative side-bending roentgenograms.
Selective thoracic fusion can be safely performed on a Type-II curve of
less than 80 degrees, but care must be taken to use the vertebra that is
neutral and stable so that the lower level of the fusion is centered over
the sacrum. The lumbar curve spontaneously corrects to balance the thoracic
curve when selective thoracic fusion is performed and the lower level of
fusion is properly selected. In Type-III, IV, and V thoracic curves the
lower level of fusion should be centered over the sacrum to achieve a
balanced, stable spine.