Idiopathic scoliosis

Idiopathic scoliosis is a deformity of the spine characterized by lateral deflection and rotation of the vertebral bodies. The disease typically presents in patients 10–12 years of age and is seen more commonly in girls. The most common pattern of scoliosis is a right convex curvature of the thoracic spine, resulting in forward rotation and protrusion of the right shoulder. Initially, patients do not experience any symptoms. The disease is often diagnosed incidentally or following manifestation of obvious skeletal deformities. Since scoliosis is a progressive condition, later symptoms can include pain and reduced mobility due to degenerative lesions of spinal discs and vertebrae. In severe cases of spinal deformity, patients may show signs of pulmonary restriction, including dyspnea and difficulty breathing. Scoliosis is a clinical diagnosis that is confirmed by typical findings on x-ray (e.g., Cobb angle > 10°). Treatment initially consists of observation and the use of braces. In cases of severe or rapidly progressing scoliosis, surgical treatment is necessary.

• Deformity of the spine occurring during growth, characterized by a lateral curvature; (Cobb angle > 10°) and simultaneous rotation of the vertebrae

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

References:^[1]

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

• According to age
  • ≥ 10 years: adolescent idiopathic scoliosis
    • ♀ > ♂
    • Most frequent type (∼ 80% of cases)
    • Usually manifests as a right convex thoracic curvature
  • 4–9 years: juvenile idiopathic scoliosis ^[2]
    • ♂ > ♀
    • Usually manifests as a left convex thoracic curvature
    • Deteriorates progressively ^[2]
  • 0–3 years: infantile idiopathic scoliosis
    • ♂ = ♀
    • Often manifests as a convex thoracic curvature with bending to the left
  • Special type: congenital functional scoliosis
    • This term does not refer to a structural scoliosis, but rather to a functional (nonstructural) type that may occur during the first months of life.
    • It usually manifests as a C-shaped, elongated thoracolumbar curvature with bending to the left, showing only a small degree of rotation.
    • Usually heals spontaneously
• According to the pattern of the curvature: C-shaped scoliosis, S-shaped scoliosis, double S-shaped scoliosis (triple scoliosis)
• According to the apex of the major curvature
  • Cervical: C2 to C6
  • Cervicothoracic: C7 to T1
  • Thoracic: T2 to T11
  • Thoracolumbar: T12 L1
  • Lumbar: L2 and L4
  • Lumbosacral: L5 or below

• Patients present because of noticeable deformities, which are especially visible on physical examination.
  • Evaluation of the spinal shape from the back of the head to the intergluteal cleft
  • Adam forward bend test (most important clinical test) may show :
    • Thoracic rotation ("rib hump")
    • Lumbar rotation ("lumbar hump")
    • Asymmetry of the waistline, leg length discrepancy
    • Asymmetry of the shoulder girdles, protrusion of the scapulae
      • C or S-shaped lateral deviation of the spinous processes
      • Compensatory reverse deflection of the spine
  • Assessment of severity based on scoliometer measurements (see “Diagnosis”)
• Respiratory and cardiopulmonary impairment in cases of severe thoracic deformity
  • Dyspnea, difficulty breathing (thoracic restriction)
  • Cor pulmonale with right heart failure as a late sequela
• Pain occurs secondary to degeneration, compression, or irritation of spinal discs and nerves.

The elevated part of the rib cage and the lumbar hump are always seen on the convex side of the deformity. In the most common form of scoliosis, the right convex thoracic curvature results in forward rotation and elevation of the right scapula.

Conventional x-ray

• Indicated to evaluate necessity for treatment (see “Treatment” below”)
• Performed in cases of deviations > 7° on scoliometer measurements
• Evaluation of the lateral curvature (in anterior-posterior projection, full-length views)
  • Major curvature: highest deviation from the perpendicular
  • Minor curvatures: compensatory deviations from the midline above and below the major curvature
  • Cobb angle: refers to the angle between the following lines
    • 1. Perpendicular to a line drawn across the superior endplate of the highest affected vertebra
    • 2. Perpendicular to a line drawn across the inferior endplate of the lowest affected vertebra
• Estimation of vertebral rotation (Nash and Moe method): assessment of the position of the vertebral pedicles is relation to the vertebral bodies
• Evaluation of skeletal maturity based on lateral ossification of the apophysis across the iliac crest (Risser sign) → relevant for prognosis
• Lateral bending imaging of the spine: evaluation of curve flexibility

Every school-aged child should undergo a physical examination of the spine in order to rule out scoliosis. Scoliosis is frequently an incidental finding.

Secondary scoliosis

• Congenital (e.g., unilateral fusion of L5 with the sacrum)
• Neuromuscular diseases (e.g., muscular dystrophy, spina bifida, Friedreich ataxia) ^[1]
• Metabolic diseases (e.g., rickets) ^[3]
• Connective tissue disease (e.g., Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta)
• Anatomic malformations (e.g., isolated difference in leg length, secondary to trauma or tumors)
  • Including Leg-length discrepancy

Leg-length discrepancy (short-leg syndrome)

• Definition: A condition caused by a difference in length between each lower extremity that results in functional impairment, compensatory structural and gait abnormalities, and degenerative joint processes.
• Etiology
  • Idiopathic
  • Trauma
  • Infection (e.g., osteomyelitis)
  • Congenital (e.g., neurofibromatosis, osteochondrodysplasias)
• Clinical features
  • Abnormal gait (often presents in childhood)
  • Lower back pain
  • Noticeable deformities (e.g., scoliosis)
  • Somatic dysfunction
  • Progressive joint degeneration
• Physical examination
  • Abnormalities in gait
  • Rotated pelvis
  • Unleveling of the sacrum
  • Lateral thoracic and lumbar curvatures
• Diagnostics
  • Standing postural x-ray: for quantifying disparities in femoral head height
  • Scanogram
  • Computerized tomography (CT) scan
• Treatment
  • Nonsurgical approach
    • Observation: if a child has not reached skeletal maturity
    • Shoe-lifts: if a femoral head difference > 5mm is present in a postural standing x-ray
      • Patients who are older, in acute pain, or have predisposing conditions (e.g., arthritis, osteoporosis): initially 1/16 inch, increased by another 1/16th inch every two weeks until a final heel lift of ½–¾ of the initially measured discrepancy is reached
      • Young and otherwise healthy patients: initially 1/8th inch, increased by another 1/8th inch every two weeks
  • Surgical approach
    • Epiphysiodesis (surgical fusing of the growth plate)
    • Limb lengthening or shortening procedures

The differential diagnoses listed here are not exhaustive.

• Treatment based on the Cobb angle ^[4]
  • Cobb angle < 10°: per definition not scoliosis, and therefore not monitored
  • Cobb angle 10–19°: continual monitoring for progression
  • Cobb angle 20–25°: monitoring or bracing
  • Cobb angle 26–45°: bracing
  • Cobb angle 46–50°: bracing or surgery
  • Cobb angle > 50° or rapidly progressing scoliosis: surgery

• Bracing ^[3]
  • 18 hours/day, if possible
  • Bracing is usually able to halt progression, but cannot cure the underlying condition.
• Surgery
  • Goal: correct spinal arching and rotation
  • Various surgical techniques and approaches exist (ventral, lateral, dorsal, or combined approach).
  • Spondylodesis: fusion of the vertebrae by bridge plating or by internal fixation ^[3]
  • Risks: paraplegia (< 1% of cases), development of pseudarthroses, infection of surgical material