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Adolescent Idiopathic Scoliosis & Early Onset Scoliosis

What is Adolescent Idiopathic Scoliosis & Early Onset Scoliosis?

Adolescent Idiopathic Scoliosis (AIS) is a three‑dimensional curvature of the spine that appears in otherwise healthy children between around 10 and 18 years of age, with no identifiable underlying cause. By definition, the curve measures at least 10 degrees on standing X‑rays and is not due to congenital vertebral abnormalities, neuromuscular conditions, or syndromes.​

Early Onset Scoliosis (EOS) describes any structural spinal curve that begins before the age of 10, and may be idiopathic or associated with congenital vertebral malformations, neuromuscular conditions, chest wall abnormalities, or syndromes. Because EOS occurs while the lungs and chest are still developing, untreated or severe curves can affect breathing, growth, and overall health more significantly than later‑onset scoliosis.​

AIS is the most common type of scoliosis seen in otherwise healthy school‑aged children and teenagers, accounting for the majority of paediatric scoliosis presentations. EOS, although less common, is more complex to manage and usually requires earlier and closer monitoring, often in a specialised paediatric spine service.

Symptoms

AIS and EOS can be subtle in the early stages and are often first noticed by parents, teachers, or during routine screening rather than by the child. Common signs and symptoms include:

  • Uneven shoulders, with one shoulder or shoulder blade sitting higher or more prominent than the other when viewed from behind.
  • A visible curve in the back, or the trunk appearing shifted so the head is not centred over the pelvis.
  • Ribs or one side of the back appearing more prominent when the child bends forward (rib or lumbar “hump”).​
  • Uneven waist or hips, with one hip appearing higher or clothes hanging unevenly.
  • In many children, little or no pain; when present, pain is usually mild and activity‑related rather than constant or night‑waking.

In EOS, additional concerns may include reduced exercise tolerance, shortness of breath with activity, or failure to thrive in more severe or syndromic cases. Red flag symptoms such as significant back pain, neurological signs (weakness, altered sensation), or bowel and bladder changes require urgent assessment to exclude other causes.

Causes

The term “idiopathic” means the exact cause is unknown, but several contributing factors have been identified. For AIS, current evidence suggests:

  • A genetic predisposition, with scoliosis clustering in families and multiple genes likely involved in curve susceptibility and progression.
  • Growth‑related factors, with curves often accelerating during rapid growth spurts around puberty, especially in girls
  • Subtle alterations in spinal growth, balance, or neuromuscular control, though no single mechanism fully explains all cases.

In EOS, the underlying cause is more often identifiable than in AIS. Common categories include:

  • Idiopathic EOS, where no specific cause is found but the curve starts before age 10.
  • Congenital scoliosis from abnormal vertebral formation or segmentation present from birth.
  • Neuromuscular scoliosis associated with conditions such as cerebral palsy, muscular dystrophy, or spinal muscular atrophy.
  • Syndromic scoliosis linked to conditions such as Marfan syndrome or neurofibromatosis.

Diagnosis

Diagnosis focuses on confirming a true structural curve, assessing severity and flexibility, and ruling out atypical causes. Key steps usually include:

  • Detailed history including age at onset, growth stage, family history, and presence or absence of pain or neurological symptoms.
  • Physical examination assessing shoulder and pelvic alignment, trunk shift, leg length, and a forward‑bend (Adam’s) test to detect rib or lumbar prominence
  • Use of a scoliometer during forward bending; readings above around 5–7 degrees typically warrant further imaging.

Imaging is essential to characterise the curve and plan treatment. This usually involves:

  • Full‑length, standing posteroanterior (PA) and lateral spine X‑rays to measure curve size (Cobb angle), curve pattern, and skeletal maturity (for example, Risser grade).
  • MRI in younger children, atypical curves (for example left thoracic curves), rapid progression, or when neurological signs are present, to exclude intraspinal anomalies such as tethered cord or syrinx.

AIS is diagnosed when a structural curve of at least 10 degrees is present in a child aged 10–18 years, with no underlying congenital, neuromuscular, or syndromic cause identified. EOS is diagnosed when structural scoliosis is identified before age 10, with further classification based on cause (idiopathic, congenital, neuromuscular, syndromic).

Treatment and Surgical Management

Treatment is individualised and depends on the child’s age, remaining growth, curve size, pattern, and rate of progression. The shared goal is to guide the child safely to skeletal maturity with a balanced spine that is unlikely to progress in adult life.​

For AIS, common treatment pathways include:

  • Observation with periodic review and X‑rays for smaller curves (typically under 20 degrees) in growing children, and for moderate curves in those nearing skeletal maturity.
  • Bracing for flexible curves generally between 20 and 40 degrees in skeletally immature patients, to slow or prevent progression during growth; good brace compliance is strongly linked with success.
  • Scoliosis‑specific physiotherapy and core/postural programmes as an adjunct to observation or bracing, to support posture, strength, and comfort, while recognising they do not by themselves “straighten” a structural curve.
  • Surgical management (for example, posterior spinal instrumented fusion or growth‑modulation techniques in selected cases) when curves are typically above 40–50 degrees, progressing rapidly, or causing significant functional or cosmetic impact despite non‑operative care.

For EOS, treatment must balance curve control with preservation of spinal and thoracic growth. Depending on age, aetiology, and severity, options may include:

  • Close observation and physiotherapy for very mild, non‑progressive curves, with regular growth and lung function monitoring.
  • Serial casting (such as Mehta casting) and bracing in younger children, particularly in idiopathic EOS, to guide spinal growth and sometimes achieve partial or complete correction without early fusion.
  • Growth‑friendly surgical techniques, such as growing rods, magnetically controlled rods, growth‑guidance systems, or vertebral body tethering in selected idiopathic cases, when conservative measures no longer control curve progression.
  • Definitive fusion once sufficient growth has occurred, or when severe curves, cardiopulmonary compromise, or failure of growth‑friendly strategies necessitate a more permanent correction.

Early identification and timely referral to a paediatric spine service are key, particularly for children with significant curves, high growth potential, or features suggesting atypical scoliosis. With modern non‑operative and surgical options, most children and adolescents with AIS or EOS can expect to maintain active, fulfilling lives, with tailored plans to support spinal health into adulthood.