School children were during this period believed to develop poor posture as a result of working at their desks, and many were diagnosed with scoliosis. It was also considered to be caused by tuberculosis or poliomyelitis, diseases that were successfully managed using vaccines and antibiotics.The American orthopaedic surgeon Alfred Shands Jr. discovered that two percent of patients had non-disease related scoliosis, later termed idiopathic scoliosis, or the "cancer of orthopaedic surgery". These patients were treated with questionable remedies. A theory at the time—now discredited—was that the condition needed to be detected early to halt its progression, and so some schools made screening for scoliosis mandatory. Measurements of shoulder height, leg length and spinal curvature were made, and the ability to bend forwards, along with body posture, was tested, but students were sometimes misdiagnosed because of their poor posture.An early treatment was the Milwaukee brace, a rigid contraption of metal rods attached to a plastic or leather girdle, designed to straighten the spine. Because of the constant pressure applied to the spine, the brace was uncomfortable. It caused jaw and muscle pain, skin irritation, as well as low self-esteem. Surgery
In 1962, the American orthopaedic surgeon Paul Harrington introduced a metal spinal system of instrumentation that assisted with straightening the spine, as well as holding it rigid while fusion took place. The now obsolete Harrington rod operated on a ratchet system, attached by hooks to the spine at the top and bottom of the curvature that when cranked would distract—or straighten—the curve.
The prevalence of scoliosis is 1% to 2% among adolescents, but the likelihood of progression among adolescents with a Cobb angle less than 20° is about 10% to 20%.Congenital scoliosis can be attributed to a malformation of the spine during weeks three to six in utero due to a failure of formation, a failure of segmentation, or a combination of stimuli. Incomplete and abnormal segmentation results in an abnormally shaped vertebra, at times fused to a normal vertebra or unilaterally fused vertebrae, leading to the abnormal lateral curvature of the spine. Resulting from other conditions
Secondary scoliosis due to neuropathic and myopathic conditions can lead to a loss of muscular support for the spinal column so that the spinal column is pulled in abnormal directions. Some conditions which may cause secondary scoliosis include muscular dystrophy, spinal muscular atrophy, poliomyelitis, cerebral palsy, spinal cord trauma, and myotonia. Scoliosis often presents itself, or worsens, during an adolescents growth spurt and is more often diagnosed in females than males.Scoliosis associated with known syndromes is often subclassified as "syndromic scoliosis".