and is custom-made from fiberglass or plastic. it is typically recommended to be worn 22–23 hours a day, and applies pressure on the curves in the spine. the effectiveness of the brace depends on not only brace design and orthotist skill, but also people's compliance and amount of wear per day. an alternative form of brace is a nighttime only brace, that is worn only at night whilst the child sleeps, and which overcorrects the deformity. whilst nighttime braces are more convenient for children and families, it is unknown if the effectiveness of the brace is as good as conventional braces. the uk government have funded a large clinical trial (called the basis study) to resolve this uncertainty. the basis study is ongoing throughout the uk in all of the leading uk children's hospitals that treat scoliosis, with families encouraged to take part. indications for bracing: people who are still growing who present with cobb angles less than 20° should be closely monitored. people who are still growing who present with cobb angles of 20 to 29° should be braced according to the risk of progression by considering age, cobb angle increase over a six-month period, risser sign, and clinical presentation. people who are still growing who present with cobb angles greater than 30° should be braced. however, these are guidelines and not every person will fit into this table. for example, a person who is still growing with a 17° cobb angle and significant thoracic rotation or flatback could be considered for nighttime bracing. on the opposite end of the growth spectrum, a 29° cobb angle and a risser sign three or four might not need to be braced because the potential for progression is reduced. the scoliosis research society's recommendations for bracing include curves progressing to larger than 25°, curves presenting between 30 and 45°, risser sign 0, 1, or 2 (an x-ray measurement of a pelvic growth area), and less than six months from the onset of menses in girls. scoliosis braces are usually comfortable, especially when well designed and well fitted, also after the 7- to 10-day break-in period. a well fitted and functioning scoliosis brace provides comfort when it is supporting the deformity and redirecting the body into a more corrected and normal physiological position. evidence supports that bracing prevents worsening of disease, but whether it changes quality of life, appearance, or back pain is unclear. surgery preoperative (left) and postoperative (right) x-ray of a person with thoracic dextroscoliosis and lumbar levoscoliosis: the x-ray is usually projected anteroposterior, such that the right side of the subject is on the right side of the image; i.e., the subject is viewed from the rear (see left image; the right image is seen from the front). this projection is typically used by spine surgeons, as it is how surgeons see their patients when they are on the operating table (in the prone position). this is the opposite of many chest radiographs, where the image is posteroanterior, i.e. projected as if looking at the patient from the front. the surgery was a fusion with instrumentation. surgery is usually recommended by orthopedists for curves with a high likelihood of progression (i.e., greater than 45 to 50° of magnitude), curves that would be cosmetically unacceptable as an adult, curves in people with spina bifida and cerebral palsy that interfere with sitting and care, and curves that affect physiological functions such as breathing. surgery is indicated by the society on scoliosis orthopaedic and rehabilitation treatment (sosort) at 45 to 50° and by the scoliosis research society (srs) at a cobb angle of 45°. sosort uses the 45 to 50° threshold as a result of the well-documented, plus or minus 5° measurement error that can occur while measuring cobb angles. surgeons who are specialized in spine surgery perform surgery for scoliosis. to completely straighten a scoliotic spine is usually impossible, but for the most part, significant corrections are achieved. the two main types of surgery are: anterior fusion: this surgical approach is through an incision at the side of the chest wall. posterior fusion: this surgical approach is through an incision on the back and involves the use of metal instrumentation to correct the curve. one or both of these surgical procedures may be needed. the surgery may be done in one or two stages and, on average, takes four to eight hours. a new tethering procedure (anterior vertebral body tethering) may be appropriate for some patients. spine surgery can be painful and may also be associated with post-surgical pain. different approaches for pain management are used in surgery including epidural administration and systemic analgesia (also known as general analgesia). epidural analgesia medication are often used surgically including combinations of local anesthetics and pain medications injected via an epidural injection. evidence comparing different approaches for analgesia, side effects or benefits, and which approach results in greater pain relief and for how long after this type of surgery is of low to moderate quality. 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 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 found to be 2% more 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. a scoliosis spinal column curve of 10° or less affects 1.5% to 3% of individuals. the age of onset is usually between 10 years and 15 years (can occur at a younger age) in children and adolescents, making up to 85% of those diagnosed. this is seen to be due to rapid growth spurts occurring at puberty when spinal development is most relenting to genetic and environmental influences. because female adolescents undergo growth spurts before postural musculoskeletal maturity, scoliosis is more prevalent among females. although fewer cases are present today using cobb angle analysis for diagnosis, scoliosis remains a prevailing condition, appearing in otherwise healthy children. despite the fact that scoliosis is a disfigurement of the spine, it has been shown to influence the pneumonic function, balance while standing and stride execution of kids with scoliosis. the impacts of backpack carriage on these three side effects have been broadly researched. incidence of idiopathic scoliosis (is) stops after puberty when skeletal maturity is reached, however, further curvature may proceed during late adulthood due to vertebral osteoporosis and weakened musculature. history female with lateral curvature of the spine ever since the condition was discovered by the greek physician hippocrates, a cure has been sought. treatments such as bracing and the insertion of rods into the spine were employed during the 1900s. in the mid-20th century, new treatments and improved screening methods have been developed to reduce the progression of scoliosis in patients and alleviate their associated pain. 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 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 a 14–15th-century woman who had severe scoliosis, and died at about 35 years, limburgs museum venlo 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. other apes have a shorter and less mobile lower spine than humans. some of the lumbar vertebrae in pan are "captured", meaning that they are held fast between the ilium bones of the pelvis. compared to humans, old world monkeys have far larger erector spinae muscles, which are the muscles which hold the spine steady. these factors make the lumbar spine of most primates less flexible and far less likely to deviate than those of humans. while this may explicitly relate only to lumbar scolioses, small imbalances in the lumbar spine could precipitate thoracic problems as well. scoliosis may be a byproduct of strong selection for bipedalism. for a bipedal stance, a highly mobile, elongated lower spine is very beneficial. for instance, the human spine takes on an s-shaped curve with lumbar lordosis, which allows for better balance and support of an upright trunk. selection for bipedality was likely strong enough to justify the maintenance of such a disorder. bipedality is hypothesized to have emerged for a variety of different reasons, many of which would have certainly conferred fitness advantages. it may increase viewing distance, which can be beneficial in hunting and foraging as well as