Dr. Clarke and his team have shown that ST2R reduction technique (Simultaneous Translation on Two Rods) associated with the PASS ® system gave a good correction of the thoracic hypokyphosis of idiopathic scoliosis. The results of his single-center studies have shown that ST2R technique allowed to restore normal thoracic kyphosis with an average gain of 23 ° in patients preoperatively hypokyphosis, higher than the gains made by other techniques (rotation of the shaft, close off Gradually, in situ bending), while providing a frontal correction 70%, similar to results reported by other techniques. The results of this technique for non idiopathic scoliosis are still to be analyzed.