Scheuermann's disease is not really a disease, but a growth anomaly that produces a forward flexion in the thoracic spine. The thoracic spine normally has between 20 and 40 degrees of kyphosis to aid in balancing the spine and skeleton as a whole. During development, if the anterior portion of the vertebral body does not grow quite as fast as the posterior part, the vertebral bodies end up with a slight wedge shape that angles the spine forward into kyphosis. This may produce the hump back or gibbus directly over the mid portion of the thoracic spine. A thoracic kyphosis of greater than 40 degrees with structural changes in the vertebral bodies is considered Scheuermann's.
Often the deformity is painless with a mild ache associated with heavy activity. If the deformity is progressive as growth occurs, sometimes back pain will become more common. Generally observation is the treatment for curves of up to 60 degrees. In a skeletally immature spine still undergoing growth, bracing may be recommended for higher degree curves. Physical therapy, while it won't change the deformity, may help to strengthen trunk muscles and alleviate some of the pain.
In rare instances surgery may be advised. Generally, these are for large deformities with significant cosmetic problems. There may be pain associated and very rarely neurological problems, in the legs or bowel and bladder function.