The scientific basis of treatment of idiopathic thoracic scoliosis.

The three-dimensional shape of the scoliotic spine must be understood and in particular the lordotic lateral profile addressed before successful derotation can be achieved. It is important that the thoracic kyphosis be recreated, firstly so that the spine can be untwisted, and secondly to bring the thoracic spine once again behind its axis of rotation thus preventing postoperative buckling with the remainder of growth. Stiffer curves require preliminary anterior multiple discectomy with growth plate excision and reshaping of the apical vertebral bodies. The deformity rapidly collapses into himself and 75% of the total correction occurs spontaneously before the second instrumentation stage. The most rigid curves require that the spinal column be shortened at bone level and Leatherman's two-stage wedge resection is ideal for this purpose. For very young spines posterior fusion is both illogical and harmful and it is essential that the growth of the front of the spine be arrested by multiple discectomy and end-plate excision. Posterior instrumental recreation of the thoracic kyphosis without fusion in a "trolley-like" procedure allows continued posterior spinal growth.