Scoliosis

• Scoliosis is a three-dimensional deformity of the spine: a lateral (sideways) curvature together with rotation of the vertebrae. A curve is only called scoliosis when the Cobb angle is 10 degrees or more on a standing radiograph and the vertebrae are rotated. ^[1][6]
• Most cases are idiopathic, meaning no cause is found. Adolescent idiopathic scoliosis is by far the commonest type, and larger curves are much more likely in girls.
• A curve that straightens when the child bends or lies down is postural, not structural, and needs a different line of thought.
• The usual screen is the Adams forward bend test, often with a scoliometer; an angle of trunk rotation under 5 degrees usually needs no follow-up, 5 to 9 degrees warrants re-examination in 6 months, and 10 degrees or more needs a radiograph. ^[2][6]
• Treatment is driven by the Cobb angle and by how much growing the child has left: observation for smaller curves, bracing for moderate progressive ones, surgery for large or progressive ones.
• Some causes are serious and must not be missed: congenital vertebral malformations present from birth, neuromuscular conditions such as cerebral palsy and Duchenne muscular dystrophy, and atypical features such as pain, neurological signs or a left thoracic curve.

By the end of this page you should be able to:

1. Define scoliosis in three dimensions and distinguish a structural curve from a postural one.
2. Explain why adolescent idiopathic scoliosis is more common and more progressive in girls, and list the age groups of idiopathic scoliosis.
3. Perform and interpret the Adams forward bend test and a scoliometer reading, and state when a radiograph is justified.
4. Measure or describe the Cobb angle and use it, with skeletal maturity, to choose between observation, bracing and surgery.
5. Recognise congenital and neuromuscular scoliosis, plan their associated investigations, and describe their management principles.
6. List the red flags that point away from idiopathic scoliosis and need urgent investigation.
7. Outline the complications of scoliosis, the role of screening, and long-term outcomes.

A curve that is seen only in the coronal plane (sideways lean) but has no vertebral rotation is not true scoliosis. It may be the result of pain, an intraspinal problem, a tumour, infection, or a leg-length difference, and its cause should be investigated. ^[1]

The Scoliosis Research Society divides idiopathic scoliosis by age at diagnosis: infantile scoliosis in children aged 0 to 3 years, juvenile scoliosis aged 4 to 10 years, and adolescent idiopathic scoliosis in those older than 10 years. ^[1]

In structural scoliosis the spine has deformed in both the coronal and axial planes. The causes are:

• Idiopathic (no identifiable cause): the commonest overall group, subdivided by age.
• Congenital: a vertebral malformation present from birth (failure of formation or segmentation of vertebrae).
• Neuromuscular: a spinal curve arising from a neurological or muscular disorder such as cerebral palsy, Duchenne muscular dystrophy, spinal muscular atrophy or myelomeningocele.
• Syndrome-related: conditions such as neurofibromatosis, Marfan syndrome and Ehlers-Danlos syndrome. ^[1]

Postural scoliosis is a lateral curve without fixed vertebral rotation. Typical situations include a leg-length difference making the spine tilt away from the pelvis, pain from another condition (an antalgic or "pain-provoked" curve), or habit. The curve is usually flexible and disappears on lying down. The important point is that postural scoliosis is not treated as scoliosis: the underlying cause is treated, and the curve is not braced or operated on. ^[1]

A useful trap is the curve that looks like idiopathic scoliosis but is actually a painful curve: back pain that is severe, unremitting, worse at night or improved by non-steroidal anti-inflammatory drugs can be produced by an osteoid osteoma, spondylolysis, infection or an intraspinal lesion, and these need investigation. ^[1]

• Infantile (0 to 3 years): about 0.5% of idiopathic scoliosis. Often associated with plagiocephaly, hip dysplasia and congenital heart disease, and most (around 90%) resolve spontaneously. ^{[1] [3]}
• Juvenile (4 to 10 years): about 10.5% of idiopathic scoliosis. Often progressive and, because of remaining growth, can become severe; curves that reach 30 degrees are almost always progressive. ^[1]
• Adolescent (older than 10 years): about 89% of idiopathic scoliosis. Presents around the adolescent growth spurt. ^[1]

Idiopathic scoliosis is by far the commonest form of spinal deformity. Idiopathic scoliosis in general (curves greater than 10 degrees) has a prevalence of about 1 to 3 per 100 people, in an equal proportion of boys and girls. Curves greater than 30 degrees are rarer, at 1 to 3 per 1000, with a ratio of boys to girls of about 1 to 8. ^[1]

Adolescent idiopathic scoliosis is by far the most common single type, since adolescent (older than 10 years) cases make up about 89% of all idiopathic scoliosis. Curves greater than 10 degrees have a general prevalence of about 1 to 3 per 100. ^[1]

Both boys and girls are affected, but girls are more likely to develop larger curves that require medical care. ^[2] Siblings and children of patients with scoliosis also have a higher incidence than the general population. ^[1]

About 30% of patients with adolescent idiopathic scoliosis have a family history of the condition, which supports a genetic component even though the mode of inheritance is complex. ^[2] Males and females are about equally likely to have a minor curve of roughly 10 degrees, but females are five to 10 times more likely to progress to severe disease that may need treatment. ^[6]

The aetiology of idiopathic scoliosis is not known. It is not caused by carrying heavy bags or poor posture, and it is not related to specific activities. Research indicates that genetics plays a role in some cases. ^[2]

For congenital scoliosis the causes are developmental (see below). For neuromuscular scoliosis the underlying diagnosis is the cause, and its natural history is generally progressive, particularly in more severely affected patients. ^[5]

In the coronal plane the spine is normally straight. Scoliosis is a failure of that alignment. Because the spine is also a rotational structure, a structural scoliosis produces a rib hump on one side of the back when the child bends forwards (the forward bend test). The apex of a typical thoracic curve is usually to the right. ^[1]

In idiopathic disease, growth is the engine. Curves progress most rapidly during the adolescent growth spurt, and risk factors for progression include female sex, a curve magnitude greater than 50 degrees at maturity, curve type (thoracic apex above T12), and remaining skeletal growth. Clinically, growth is estimated from age (girls grow on average until about 14 years and boys until about 16 years), menarche status (growth is fastest in the six months before menarche and usually stops about two years after menarche), and peak height velocity. Radiographically, closure of the triradiate cartilage and ossification of the iliac crest apophysis (the Risser sign) mark remaining growth. ^[1]

Idiopathic scoliosis is largely a cosmetic and progressive deformity in adolescence. Curves that stay under about 30 degrees after skeletal maturity usually do not progress; most curves over 50 degrees continue to progress at roughly 1 degree per year. Severe thoracic curves of 90 to 100 degrees or more can impair pulmonary function and increase the risk of right heart failure (cor pulmonale). Back pain is slightly more common in young people with scoliosis than in the general population. ^[1]

Congenital scoliosis arises from a malformation of the vertebrae that is present from birth, due to failure of formation or failure of segmentation (or both) during the fourth to sixth week of gestation, when the spine is forming together with the genitourinary, musculoskeletal and cardiovascular systems. ^[3][4]

Types of vertebral anomaly:

• Failure of formation: hemivertebra (semi-segmented, fully segmented or wedge vertebra).
• Failure of segmentation: unilateral unsegmented bar, or block (fused) vertebra.
• Mixed defects.

The worst prognosis for progression belongs to a unilateral unsegmented bar with a contralateral hemivertebra; the most benign is a complete block vertebra or an incarcerated (non-progressive) hemivertebra. A fully segmented hemivertebra surrounded by healthy disc spaces predicts more progression, and more than one hemivertebra speeds progression. ^[3][4]

The curvature behaves dynamically:

• About 25% of congenital curves do not progress.
• About 25% progress mildly.
• About 50% progress and need treatment, depending on age, curve characteristics and anomaly type. ^[4]

Progression is fastest before the age of 5 years and during the adolescent growth spurt (11 to 14 years), and thoracolumbar curves progress faster than midthoracic ones. Curves present before the age of 10, and especially in the first year of life, carry a worse prognosis. ^{[4] [3]}

Neuromuscular scoliosis results from muscular imbalance and lack of trunk control around an otherwise normally formed spine. It is usually first identified in early childhood and tends to progress relentlessly in more severely affected patients, altering sitting balance, seating, hygiene and, eventually, cardiopulmonary function. ^[5]

Common underlying conditions include:

• Cerebral palsy (the most common cause).
• Duchenne muscular dystrophy.
• Spinal muscular atrophy.
• Myelomeningocele.
• Friedreich ataxia.
• Spinal cord injury. ^[5]

A child or adolescent usually presents with chest wall or back asymmetry noticed by parents, during school screening or at a routine check. Posterior rib prominence is the most visible sign. Adolescents may notice shoulder or breast asymmetry. ^[1]

Beyond appearance, take a careful history:

• Age at onset: onset before 10 years points towards non-idiopathic scoliosis. ^[1]
• Back pain: about a quarter of patients with adolescent idiopathic scoliosis have back pain. Pain in scoliosis is usually mild and on the side of the rib prominence. Severe, unremitting back pain, worse at night, improving with non-steroidal anti-inflammatory drugs, or pain with fever, is atypical and should be investigated for infection, tumour, spondylolysis or an intraspinal problem. ^{[1] [6]}
• Neurological symptoms: weakness, sensory change, gait or coordination problems, or bowel or bladder disturbance. Significant changes suggest an intraspinal problem such as syringomyelia, tethered cord or tumour. ^[1]
• Growth and puberty: height trajectory, menarche, pubertal stage; these estimate remaining growth and therefore progression risk. ^[1]
• Family history: of scoliosis. ^[1]
• Associated features: symptoms of Marfan or Ehlers-Danlos syndrome, neurofibromatosis, or a neuromuscular condition. ^[1]

Begin with the whole patient: height measurement, gait, foot shape, skin (cafe-au-lait spots, axillary freckles, hairy patches, dimples), pubertal stage, neurological examination, and overall appearance. ^[1]

• Posture and alignment: shoulder and iliac crest symmetry, trunk shift, head position over the sacrum.
• Neurological examination: balance, motor and sensory testing in all lower extremity groups, reflexes, Babinski sign, abdominal reflexes. Abnormalities may indicate an intraspinal disorder such as syringomyelia. ^[1]
• Skin inspection: cafe-au-lait spots or axillary freckles suggest neurofibromatosis; a hairy patch or skin dimpling suggests spinal dysraphism. ^[1]
• Leg lengths: a significant discrepancy produces an oblique take-off of the spine from the pelvis (postural curve). ^[1]
• Curvatures: look for the rib hump and waist asymmetry with the patient upright.

A scoliometer (inclinometer) is then placed on the back along the curve and measures the angle of trunk rotation. Generally, an angle of trunk rotation under 5 degrees is insignificant and may not need follow-up, a measurement of 5 to 9 degrees at least warrants re-examination in 6 months, and a measurement of 10 degrees or greater requires radiologic evaluation for the Cobb angle. ^[6]

Note that a curve that only appears when the patient bends is postural; a true structural scoliosis remains and shows a rib hump on bending. ^[1]

Pain on performing the test, or hamstring tightness preventing it, suggests something other than idiopathic scoliosis, such as mechanical back pain, disc herniation, spondylolysis or infection. ^[1]

A child with these features should be referred within one month for imaging (usually including MRI) rather than watched. ^[1]

The task is to separate true scoliosis from other causes of back asymmetry, and to separate idiopathic from non-idiopathic structural scoliosis.

Once scoliosis is suspected, obtain a standing posterior-anterior (PA) radiograph of the spine on a long cassette. The Cobb angle is measured from the vertebrae most tilted at either end of the curve (the superior end plate of the most tilted upper vertebra and the inferior end plate of the most tilted lower vertebra). A scoliometer reading is typically used before this step. ^[1][3]

Always inspect the vertebrae themselves: there should be two pedicles at every level and visible rotation at the apex. A curve in the coronal plane without rotation should prompt investigation for other causes. ^[1]

If back pain is present, add a lateral radiograph of the spine including the lumbosacral region to look for spondylolysis, spondylolisthesis, infection or destruction, and consider bone scan or MRI. ^[1]

MRI is not needed for most patients with adolescent idiopathic scoliosis. It is most useful for patients younger than 10 years at presentation, those with left thoracic curves, those with neurological abnormalities, and patients with congenital scoliosis (in whom intraspinal anomalies are common). ^[1][3][4]

Because the vertebrae, kidneys, heart and neural tube develop together, every child with congenital scoliosis should be evaluated for other anomalies: a thorough neurological and cardiac examination, an abdominal (renal) ultrasound, an echocardiogram, and MRI of the complete spine to exclude spinal dysraphism (found in roughly 17% to 37% of cases). Up to about 20% have urinary tract malformations. ^[3][4]

Skeletal maturity is estimated from the Risser sign (ossification of the iliac crest apophysis), closure of the triradiate cartilage, age, menarche and peak height velocity. Maturity matters because it determines progression risk and therefore management. ^[1]

The diagnosis of scoliosis is radiographic: a Cobb angle of at least 10 degrees with vertebral rotation. ^[1]

Idiopathic scoliosis is subdivided by age (infantile, juvenile, adolescent) as above. For adolescents, the Lenke and King-Moe systems describe curve type and guide fusion levels for surgical patients, but primary care decisions rest on angle, location and maturity. ^[1]

Management depends on the type of scoliosis, the Cobb angle, skeletal maturity and progression.

A practical flow:

Key management principles:

• Observation is used for smaller, non-progressive curves. The doctor rechecks the patient about every 6 to 12 months with radiographs until growth is complete. ^[2]
• Bracing (usually an underarm brace custom made for the child) is used for moderate curves in patients who are still growing. Bracing does not straighten an existing curve but tries to stop it from worsening to the point of surgery. ^[1][2]
• Physiotherapy and exercise are used as adjuncts; modalities such as chiropractic manipulation, electrical stimulation and physical therapy alone have questionable benefit in preventing progression of idiopathic scoliosis. ^[2]
• Surgery (spinal fusion with rods, hooks, screws or wires) is used for large or rapidly progressing curves, generally above 45 to 50 degrees, to prevent further progression and to correct the deformity. Severe untreated curves can eventually affect lung function. ^[1][2]
• Scoliosis surgery also needs postoperative follow-up; most children return to school within 4 weeks and to sport within 6 to 9 months, with contact sports discouraged. ^[2]

Treatment is based on the size of the curve, the nature of the anomaly and expected progression. Because congenital curves are rigid, bracing is generally not effective at preventing progression, although it may slow a flexible compensatory curve. ^[3]

• Curves under roughly 25 degrees, or benign anomalies such as block vertebra or incarcerated hemivertebra, can be observed with serial radiographs every 6 months during rapid growth periods. ^[3][4]
• Indications for surgery include curves over 40 degrees, curves with steady progression, and unilateral unsegmented bars with or without a contralateral hemivertebra. ^[3][4]
• Surgical options include in situ fusion, convex hemiepiphysiodesis (growth arrest on the convex side), hemivertebra excision (useful especially under 5 years of age), growing rods, and rib distraction for thoracic insufficiency. ^[3][4]
• In children with congenital scoliosis, surgery also requires neuromonitoring because of the high risk of neurological injury. ^[3]

Non-operative measures include observation, bracing (mainly as an external support for sitting balance in those with flexible curves), specialised seating, and treatment of the underlying condition. Bracing has limited long-term effect on curve progression in neuromuscular scoliosis. In Duchenne muscular dystrophy, glucocorticoid treatment has been associated with a lower incidence of scoliosis. ^{[5] [6]}

Surgical correction is considered for progressive deformity with unacceptable trunk shift or pelvic obliquity that affects standing or sitting balance, or when non-operative care fails; in some conditions, such as Duchenne muscular dystrophy, surgery may be considered earlier. The goals are a solid arthrodesis, correction of deformity and pelvis, and restoration of upright posture. Complications are more common than in idiopathic scoliosis. ^[5]

• Progression of the curve during growth, especially in females with thoracic curves above T12. ^[1]
• Respiratory compromise and, in severe thoracic curves over 90 to 100 degrees, an increased risk of cor pulmonale and right heart failure. ^[1]
• Cosmetic and psychosocial effects, including body-image concerns. ^[1]
• Back pain, which is slightly more common than in the general population. ^[1]
• Thoracic insufficiency syndrome in congenital scoliosis with rib deformities, from reduced thoracic volume. ^[3]
• Intraspinal problems if a structural curve without rotation is missed (tumour, syrinx, infection). ^[1]
• Post-surgical complications (infection, blood loss, implant-related problems) are more frequent in neuromuscular and congenital scoliosis than in idiopathic scoliosis. ^[5]

Untreated curves under about 30 degrees after skeletal maturity usually do not progress. Most curves over 50 degrees progress at roughly 1 degree per year. Long-term mortality is not increased in adolescent idiopathic scoliosis, although pulmonary function may be limited in severe deformity. ^[1]

Congenital scoliosis runs a highly variable course: about a quarter of curves do not progress, a quarter progress mildly, and half progress and need treatment. ^[4]

Neuromuscular curves usually progress, particularly in non-ambulatory or more severely affected patients. ^[5]

There is no known way for an individual to prevent idiopathic scoliosis. Exercise, swimming and posture do not prevent it, although regular physical activity remains healthy. ^[1]

Screening is controversial:

• The Scoliosis Research Society recommends annual screening of children aged 10 to 14 years. ^[1]
• The American Academy of Pediatrics has recommended screening with the forward bend test at routine visits at ages 10, 12, 14 and 16 years. ^[1]
• The US Preventive Services Task Force and the Canadian Task Force on the Periodic Health Examination found insufficient evidence to recommend for or against routine screening of asymptomatic adolescents, and concluded that the harms may exceed the benefits. ^[1]
• Most jurisdictions have abandoned routine school screening. Considering this, in most settings careful clinical examination during routine visits is the pragmatic approach. ^[1]

In practice, the Adams forward bend test at routine health supervision visits, with a scoliometer when available, is the standard screen. ^[1][2]

Adults with idiopathic scoliosis should be told that their children should be screened carefully, because there is a genetic component. ^[1]

• Infants and young children: onset of curvature before 10 years deserves investigation; radiographs or MRI may be indicated, and curves that reach 30 degrees are usually progressive. ^[1]
• Pregnancy: pregnancy is generally well tolerated after scoliosis surgery, and spinal fusion does not increase complications during pregnancy or delivery. ^[2]
• Neuromuscular patients: progression is linked to severity of neurological involvement; medical treatment of the underlying disease (for example steroids in Duchenne muscular dystrophy) can alter the natural history. ^[5]
• Low-resource settings: the standing PA radiograph and careful use of the Adams forward bend test carry most of the diagnostic weight; refer progressive or atypical curves and those over 40 to 50 degrees where surgical capacity exists. Congenital cases benefit from basic screening (renal ultrasound and echocardiogram) where available. ^[1][3]

Refer promptly (within a month, sooner if atypical) for any of:

• a curve greater than 10 degrees before 10 years of age
• a curve greater than 20 to 25 degrees in an adolescent who has not reached skeletal maturity
• atypical features (left thoracic curve, neurologic signs, significant pain, curve without rotation, rapid progression)
• congenital scoliosis, or scoliosis associated with a syndrome or neuromuscular condition
• curves greater than 40 to 50 degrees, or progressive curves despite observation or bracing ^[1][3]

• Scoliosis is a lateral curve of the spine with vertebral rotation; a Cobb angle of at least 10 degrees is required for the diagnosis. ^[1]
• A postural curve corrects on bending or lying down and has no rotation; it is not managed with bracing or surgery. ^[1]
• Most scoliosis is idiopathic; adolescent idiopathic scoliosis accounts for about 89% of idiopathic cases and is more likely to progress to a larger curve in girls. ^[1][2]
• The common general-population prevalence of curves over 10 degrees is about 1 to 3 per 100 in both sexes; curves over 30 degrees occur in 1 to 3 per 1000 with a boy-to-girl ratio of about 1 to 8. ^[1]
• Idiopathic scoliosis is divided by age into infantile (0 to 3 years, about 0.5%), juvenile (4 to 10 years, about 10.5%) and adolescent (older than 10 years, about 89%). ^[1]
• Congenital scoliosis comes from failure of formation or segmentation of vertebrae early in gestation and is associated with cardiac, renal and intraspinal anomalies. ^[3][4]
• Neuromuscular scoliosis is usually progressive and is most often due to cerebral palsy or Duchenne muscular dystrophy. ^[5]
• Screen with the Adams forward bend test and a scoliometer: under 5 degrees usually needs no follow-up, 5 to 9 degrees warrants re-examination in 6 months, and 10 degrees or more needs a radiograph. ^[6]
• The Cobb angle drives management in adolescents: observation under about 25 degrees, bracing 25 to 45 degrees, surgery above 45 to 50 degrees. ^[1][2]
• Bracing slows progression; it does not correct a curve. ^[1][2]
• Red flags (onset before 10 years, pain, neurological signs, left thoracic curve, curve without rotation) require prompt investigation. ^[1]
• Curves under 30 degrees after maturity rarely progress; most over 50 degrees progress about 1 degree per year. ^[1]

Adolescent idiopathic scoliosis; congenital scoliosis; neuromuscular scoliosis; kyphosis; lordosis; back pain in children and adolescents; spondylolysis and spondylolisthesis; Marfan syndrome; neurofibromatosis. Plain text only. (MedGrasp topics are linked once verified.)