Idiopathic scoliosis

Epidemiology & Risk Factors

• Demographics: Adolescent Idiopathic Scoliosis (AIS, age $\ge 10$ yo) is most common (~80%).
• Sex: Overall equal incidence; F:M ratio ~10:1 for severe, progressive curves.
• Progression Risk:
  • Female sex.
  • Skeletal immaturity: Premenarchal, Tanner 1–2, Risser grade 0–2, open triradiate cartilage.
  • Initial curve magnitude: Cobb angle $\ge 20^{\circ }-25^{\circ }$.

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Clinical Features

• Presentation: Painless, incidental trunk/shoulder/waist asymmetry.
• Physical Exam:
  • Adam’s Forward Bend Test: Demonstrates rotational deformity / unilateral rib hump.
  • Scoliometer: ATR $\ge 5^{\circ }-7^{\circ }$ warrants imaging.
• Red Flags (requires Spinal MRI for non-idiopathic causes):
  • Left-sided thoracic curve (levoscoliosis).
  • Neurologic signs (hyperreflexia, clonus, sensory loss).
  • Severe or nocturnal back pain; rapid progression.

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Diagnosis

• Initial/Screening: Adam’s forward bend test $\pm$ scoliometer.
• Confirmatory / Gold Standard: Standing full-length spine XR (PA and lateral). c
  • Diagnostic threshold: Cobb angle $\ge 10^{\circ }$ with vertebral rotation.
  • Risser staging (0–5): Evaluates iliac crest ossification for skeletal maturity.
• Other Studies:
  • Spine MRI: Indicated only if red flags are present.
  • PFTs: Assess for restrictive lung disease if Cobb angle $>50^{\circ }-60^{\circ }$.

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Differential Diagnostics

• Neuromuscular (CP, DMD): Diff by underlying motor impairment, rapid progression, long C-shaped curve.
• Congenital Scoliosis: Diff by intrinsic vertebral anomalies (hemivertebrae) on XR; check VACTERL/renal US.
• Syringomyelia / Chiari I: Diff by left thoracic curve, cape-like sensory loss; diagnose via MRI.
• Osteoid Osteoma: Diff by painful curve, nocturnal pain rapidly relieved by NSAIDs.
• Postural / Functional: Diff by complete resolution of asymmetry on forward bend or sitting.

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Management

• Stratified by Cobb Angle & Skeletal Maturity:

  1. Cobb Angle < 20°:

     • Observation: Serial clinical exam and spine XR every 4–6 months until skeletal maturity.

  2. Cobb Angle 20° – 40°:

     • Bracing (TLSO): Indicated if skeletally immature (Risser 0–2) + documented progression ($\ge 5^{\circ }$) or baseline $25^{\circ }-40^{\circ }$.
     • Goal: Prevents further progression (does not correct existing curve).

  3. Cobb Angle > 40° – 50°:

     • Surgical Correction: Posterior spinal fusion with instrumentation (indicated for $>40^{\circ }$ if immature, $>50^{\circ }$ if mature).

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Complications

• Severe Restrictive Lung Disease: Cobb angle $>70^{\circ }-100^{\circ }$ $\to$ $\downarrow$ TLC/FVC, hypoventilation, cor pulmonale.
• Chronic Lumbar Pain: Premature degenerative disc disease in untreated adults.
• Psychosocial Stress: Body image disturbance.