Scheuermann’s disease (SD) is a spinal condition that starts in childhood and results in excessive kyphosis. Kyphosis is a forward curvature of the spine. In SD, the child or teenager looks like he or she has a "hunchback." The section of spine affected is the thoracic spine from below the neck to the bottom of the rib cage.
The orthopedic surgeon will be able to best answer your question. X-ray measurements are taken and angles of curves are calculated in preparation for this operation. Fusion with rods alongside the spine helps stop the forward progression of this condition.
Studies show an average improvement of about 40 percent with fusion. And because a change in one curve can affect the other spinal curves, this correction also improves the low back curve called the lumbar lordosis.
The spine is a dynamic system and seems to automatically rebalance itself after fusion. This is true even in SD. Long-term studies are still needed to see if these changes are permanent.