Scoliosis is defined as a three-dimensional spinal deformity in the coronal, sagittal, and transverse planes with >10° of scoliosis on the full-length X-ray of the orthostatic spine. The most common clinical form of scoliosis is idiopathic scoliosis, which is scoliosis of unknown etiology. Idiopathic scoliosis in adolescents occurs after the age of 10 years and accelerates with accelerated growth. Mild to moderate scoliosis is generally more common, and severe scoliosis requiring treatment is less common. The incidence of mild scoliosis is similar in men and women, while the ratio of men to women in cases with severe scoliosis requiring surgery is approximately 1:8.