Studies of the natural course of untreated adolescent idiopathic scoliosis have focused on: 1. Mortality: Mortality in untreated adolescent idiopathic scoliosis patients is comparable to that of the general population. Patients with untreated adolescent idiopathic scoliosis generally do not develop pulmonary failure leading to premature death. It is important to distinguish adolescent idiopathic scoliosis from severe scoliosis (>90 degrees) with early onset (before age 5 years). Patients with early-onset scoliosis can develop pulmonary heart disease and right heart failure, leading to premature death. 2. Pulmonary and cardiac function: In the absence of significant thoracic kyphosis deficit, no significant decrease in maximum lung capacity (FVC) occurs if the thoracic curvature is less than 90 degrees. Only in patients with thoracic segmental scoliosis is there a direct relationship between the magnitude of the bend and pulmonary function. 3. Back pain: The incidence of back pain in adolescent idiopathic scoliosis patients as adults is comparable to that of the general population. The incidence of lower back pain is increased in patients with greater lumbar curvature (especially when the parietal vertebrae of the lumbar curvature appear to be in significant scoliosis displacement). 4. Self-image: Spinal deformity and the adverse effects on one’s image remain a major concern for patients in adulthood. Dissatisfaction with one’s own image is often a motivation for patients with idiopathic scoliosis to seek treatment in adulthood.