Prognosis
A 50-year follow-up study published in the Journal of the American Medical Association (2003) asserted the lifelong physical health, including cardiopulmonary and neurological functions, and mental health of people with idiopathic scoliosis are comparable to those of the general population. Scoliosis that interferes with normal systemic functions is "exceptional" and "rare", and "untreated [scoliosis] people had similar death rates and were just as functional and likely to lead productive lives 50 years after diagnosis as people with normal spines." In an earlier University of Iowa follow-up study, 91% of people with idiopathic scoliosis displayed normal pulmonary function, and their life expectancy was 2% less than that of the general population. Later (2006-) studies corroborate these findings, adding that they are "reassuring for the adult patient who has adolescent onset idiopathic scoliosis in approximately the 50–70° range." These modern landmark studies supersede earlier studies (e.g. Mankin-Graham-Schauk 1964) that did implicate moderate idiopathic scoliosis in impaired pulmonary function.Generally, the prognosis of scoliosis depends on the likelihood of progression. The general rules of progression are larger curves carry a higher risk of progression than smaller curves, and thoracic and double primary curves carry a higher risk of progression than single lumbar or thoracolumbar curves. In addition, people not having yet reached skeletal maturity have a higher likelihood of progression (i.e., if the person has not yet completed the adolescent growth spurt). Epidemiology
Scoliosis affects 2–3% of the United States population, which is equivalent to about five to nine million cases.
The Harrington rod obviates the need for prolonged casting, allowing patients greater mobility in the postoperative period and significantly reducing the quality of life burden of fusion surgery. The Harrington rod was the precursor to most modern spinal instrumentation systems. A major shortcoming was that it failed to produce a posture wherein the skull would be in proper alignment with the pelvis, and it did not address rotational deformity. As the person aged, there would be increased wear and tear, early onset arthritis, disc degeneration, muscular stiffness, and acute pain. "Flatback" became the medical name for a related complication, especially for those who had lumbar scoliosis.In the 1960s, the gold standard for idiopathic scoliosis was a posterior approach using a single Harrington rod. Post-operative recovery involved bed rest, casts, and braces. Poor results became apparent over time.In the 1970s, an improved technique was developed using two rods and wires attached at each level of the spine. This segmented instrumentation system allowed patients to become mobile soon after surgery.In the 1980s, Cotrel-Dubousset instrumentation improved fixation and addressed sagittal imbalance and rotational defects unresolved by the Harrington rod system. This technique used multiple hooks with rods to give stronger fixation in three dimensions, usually eliminating the need for postoperative bracing. Evolution
There are links between human spinal morphology, bipedality, and scoliosis which suggest an evolutionary basis for the condition. Scoliosis has not been found in chimpanzees or gorillas. Thus, it has been hypothesized that scoliosis may actually be related to humans morphological differences from these apes.