1. The prognosis of paralytic scoliosis has been studied by defining curve patterns and establishing the natural development as seen in fully grown patients who have not had surgical correction.

2. The prognosis, unlike that in idiopathic scoliosis, is related to the age of onset of the curvature and the degree of muscle imbalance rather than the site of the primary curve.

3. Paralysis of limb muscles is shown to be unrelated to the development of scoliosis. The intercostal muscles and the lateral abdominal flexors produce scoliosis when weaker on the convex side of the curve. Gravity and the other trunk muscles certainly play a part in the development of lumbar curves but their importance is difficult to assess.

Infantile idiopathic scoliosis is a structural scoliosis seen in infants, usually boys, with the major curve to the left in almost all cases, and almost invariably in the mid-or lower thoracic region. It occasionally disappears, but in general the curve tends to increase. In the absence of any discoverable etiology it is termed "idiopathic" and it is believed not to differ in essentials from the more common adolescent scoliosis.

Lumbar idiopathic scoliosis has a good prognosis as to deformity, but leads more often than any other curvature to degenerative arthritis and pain in later life.