There is a general acceptance that primary few surgical techniques aims at the improvement of the rotation de- ' formity. C-D instrumentation makes this improvement with its three dimensional correction.
The rotation angles in 12 patients with idiopathic thoracic lordoscoliosis were measured before and after the operation with CDI. The angles were measured at the apex, one vertebra upper and below. These were the vertebra where the rotation was the greatest. Preoperatively the mean rotation was 20.2 in the sagittal plane. Postoperatively this was reduced to 6,8. That means in the patients operated with CDI and derotated, there is a correction of 33,7 in the primary deformity. In the postoperative follow up, there was no change in the rotational angles.