Idiopathic scoliosis

Idiopathic scoliosis is a lateral curvature of the spine with a Cobb angle ≥ 10° on x-ray with no organic underlying cause. Simultaneous rotation of the involved vertebrae also occurs. The most common classification is adolescent idiopathic scoliosis, which occurs between 10 and 12 years of age, is more common in girls, and typically manifests with a right convex thoracic curvature. Mild scoliosis is usually asymptomatic and only suspected on routine screening. The diagnosis is confirmed with spinal x-rays. Patients with red flags for scoliosis should be evaluated for nonidiopathic causes and treated as indicated. Management of idiopathic scoliosis is based on the classification, degree of curvature, and remaining growth potential. Options include regular monitoring, physical therapy, and interventions to prevent progression (i.e., with bracing and/or surgery). Progression of idiopathic scoliosis to a severe curvature may cause pain, functional impairment, and/or thoracic restriction (e.g., pulmonary disorders and heart failure).

• Sex: ♀ > ♂ (∼ 5:1)
• The spinal curvature deformity can progress in skeletally immature patients as they grow.

Epidemiological data refers to the US, unless otherwise specified.

• Exact etiology unknown
• Genetic factors are likely
• Possible causes
  • Mismatch in growth of dorsal and ventral parts of the vertebrae: growth of vertebral arches lags behind that of vertebral bodies → impaired longitudinal growth with rotation of vertebrae → lateral curvature of the spine
  • Primary muscle or connective tissue disorders
  • Abnormal growth hormone secretion

Classification by age

• Infantile idiopathic scoliosis
  • Epidemiology: 0–3 years of age (♂ = ♀)
  • Often manifests as a left convex thoracic curvature
  • Usually resolves spontaneously without treatment ^[4]
• Juvenile idiopathic scoliosis ^[5][6]
  • Epidemiology: 4–9 years of age (♀ > ♂) ^[5]
  • Levocurvature most common in children ≤ 6 years of age; dextrocurvature most common in children > 6 years of age ^[5]
  • Surgery often required if the curve is ≥ 30° at the start of puberty ^[5]
  • Deteriorates progressively and may cause cardiopulmonary complications ^[5]
• Adolescent idiopathic scoliosis (also called “late-onset scoliosis”)
  • Epidemiology: 10–18 years of age (♀ > ♂)
  • Most common type of idiopathic scoliosis (∼ 80% of patients)
  • Usually manifests as a right convex thoracic curvature
• Adult idiopathic scoliosis: the persistence or progression of childhood idiopathic scoliosis

Classification by location

• Cervical: C2 to C6
• Cervicothoracic: C7 to T1
• Thoracic: T2 to T11
• Thoracolumbar: T12 to L1
• Lumbar: L2 to L4
• Lumbosacral: L5 or below

Idiopathic scoliosis is often asymptomatic and identified during well-child examinations or scoliosis screening. ^[2][6]

• Abnormal posture
• Anatomical asymmetries on visual inspection (e.g., during the Adam forward bend test)
• Mild pain

Severe scoliosis may cause symptoms of respiratory distress and/or symptoms of heart failure due to thoracic restriction. ^[6]

The following features are associated with nonidiopathic scoliosis and/or an increased risk of progression. ^[5][6][7][8]

• Age < 10 years (referred to as “early-onset scoliosis”) ^[8][9][10]
• Levocurvature of the thoracic spine
• Rapid onset of new scoliosis or progression of a previously stable curvature ^[10]
• Severe back pain
• Clinical features of nonidiopathic causes of scoliosis, e.g.,: ^[6]
  • Musculoskeletal findings: high-arched feet, gait instability, arachnodactyly, joint laxity
  • Focal neurological deficit: incontinence, weakness
  • Skin findings: café au lait spots, sacral dimpling, and/or sacral tuft
  • Systemic symptoms: weight loss, fever, malaise ^[5]

Some societies advocate for routine scoliosis screening. ^{[11][12][13][14]}

• Indications
  • Once at 10 and 12 years of age in girls
  • Once between 13–14 years of age in boys
• Modality: visual inspection, e.g., with Adam forward bend test ^[12][15]

Approach ^[6][8]

• Obtain a focused history and physical examination to assess for:
  • Red flags for scoliosis
  • Nonidiopathic causes of scoliosis
  • Remaining growth potential (e.g., with Tanner stage, age at menarche) ^[6]
• Inspect the patient as they stand and bend forward, preferably with scoliometer measurements.
• Obtain an x-ray in individuals with either of the following:
  • Abnormal findings on visual inspection, especially if scoliometer is unavailable
  • Angle of trunk rotation ≥ 5° or ≥ 7° (cut-offs differ) with a scoliometer ^[6][15]
• In individuals with red flags for scoliosis, consider an MRI spine to evaluate for an underlying cause and complications. ^[10]

Visual inspection ^[2][6][15]

Examine the patient from behind with their back exposed while they are in standing and bending positions.

• Standing assessment may reveal anatomical asymmetries.
  • Uneven shoulders, hips, waistline, and/or skin folds
  • Unilateral scapula protrusion
  • Uneven paravertebral muscles (may be the only abnormality in lumbar scoliosis)
  • Spinal curvature: a single C-shaped or compensatory S-shaped curvature ^[16]
• Bending assessment: Adam forward bend test with scoliometer measurements (if available) may reveal
  • A thoracic rib hump on the convex side (dextroconvex in 90% of patients) ^[7]
  • A lumbar hump on the convex side (typically levoconvex)
  • Angle of trunk rotation ≥ 5° or ≥ 7° (cut-offs vary) on scoliometer measurement ^[6][15]

Adolescent idiopathic scoliosis is most commonly a thoracic dextroscoliosis that manifests with a right rib hump, elevated right shoulder, and protruding right scapula. ^[2][6][7]

Suspect leg length discrepancy in patients with uneven iliac crests when standing and normal findings on the Adam forward bend test. ^[6]

Scoliosis x-ray ^[10]

• Modality
  • Standing full-length x-ray (PA and lateral view) of the thoracic and lumbar spine, sacrum, and pelvis ^[3][6]
  • Lateral view not needed for follow-up imaging ^[6]
• Findings
  • Cobb angle: a radiographic measurement to assess degree of spinal curvature ^[15]
    • Normal: < 10°
    • Mild scoliosis: 10–24°
    • Moderate scoliosis: 25–49°
    • Severe scoliosis: ≥ 50°
  • Risser stage: a radiographic measurement of ossification of the iliac apophysis used to estimate skeletal maturity and remaining growth potential ^[2][7][17]

An orthopedic specialist may order a bone age to further assess skeletal maturity and remaining growth potential. ^[18]

Nonidiopathic scoliosis ^{[5][6][8][10]}

• Congenital scoliosis: congenital vertebral malformations (e.g., from unilateral fusion of L5 with the sacrum)
• Neuromuscular scoliosis ^[1]
  • Cerebral palsy
  • Muscular dystrophy
  • Spina bifida
  • Friedreich ataxia ^[19]
• Syndromic scoliosis
  • Connective tissue disease (e.g., Marfan syndrome, Ehlers Danlos syndrome, osteogenesis imperfecta)
  • Neurofibromatosis type 1
• Functional scoliosis: an apparent curvature of the spine not caused by a structural abnormality of the spine ^[2][3]
  • Congenital functional scoliosis: occurs during the first months of life
    • Typically C-shaped with elongated leftward thoracolumbar curvature and only a small degree of rotation
    • Usually resolves spontaneously
  • Nonspinal anatomical abnormalities (e.g., leg length discrepancy, trauma, tumors)
  • Muscular imbalances (e.g., poor posture, pain, muscle spasms, muscle weakness)
• Other
  • Metabolic diseases (e.g., rickets)
  • Spinal tumors
  • Spinal infections
  • Adult degenerative scoliosis

Adult degenerative scoliosis ^[20][21]

• Epidemiology: typically occurs after 50 years of age ^[20]
• Etiology: degenerative changes to the spine
  • Degenerative disc disease
  • Facet joint osteoarthritis
• Clinical features
  • Pain (90% of patients) ^[21]
  • Commonly affects the lumbar region (loss of lumbar lordosis may be present)
  • Neurological symptoms (e.g., clinical features of spinal stenosis, radiculopathy)
• Diagnosis
  • All patients: scoliosis x-ray in both standing and supine positions
  • Individuals with neurological symptoms: MRI spine, CT myelogram
  • See “Diagnosis of scoliosis.”
• Management
  • Nonsevere symptoms
    • Weight loss (if indicated)
    • Physical therapy
    • Analgesia (see “Conservative management of nonspecific back pain”)
    • Epidural or nerve root injections
  • Severe neurological symptoms, refractory pain, or curve progression
    • Referral to a spine specialist
    • Surgical management (e.g., decompression, laminectomy, spinal fusion)

Adult scoliosis is typically caused by adult idiopathic scoliosis or de novo adult degenerative scoliosis. ^[20]

Bracing in adults may temporarily relieve pain but does not prevent curve progression and may contribute to paraspinal muscle deconditioning. ^[21]

The differential diagnoses listed here are not exhaustive.

Approach ^[6][7][18]

• Management varies based on the remaining growth potential and degree of spinal curvature on X-ray.
• Refer to a spine specialist (e.g., neurosurgery, orthopedics) for further management for either:
  • Red flags for scoliosis ^[8][10]
  • Cobb angle ≥ 20° ^[6][7][18]
• In individuals with Cobb angle 10–19° and no indications for referral:
  • Monitor with repeat examination and/or x-rays every 6 months until the patient has no remaining growth potential. ^[6][7][18]
  • Refer to orthopedics if curvature progresses.
• Treat any associated symptoms (e.g., mild back pain); see “Nonopioid oral analgesia in children.”

The risk for curve progression is increased in individuals with a Cobb angle of ≥ 20° if skeletally immature and > 50° if skeletally mature. ^[7][10][22]

Interventions for scoliosis ^[6][7][18]

• Bracing
  • Indication: Cobb angle 25–45° in patients with remaining growth potential ^[18]
  • Modalities: a rigid thoracolumbosacral orthosis worn for ≥ 13 hours/day ^[18]
  • May combine with scoliosis-specific physical therapy exercises
• Surgery
  • Indication: Cobb angle greater than 45–50° ^[18]
  • Modalities: posterior spinal fusion (techniques vary)

The goal of bracing and surgery is to limit or prevent the progression of scoliosis. ^[6][18]