CIM Case: Adolescent Idiopathic Scoliosis - Progressive Curve

Clinical Scenario

Patient: 12-year-old girl Presentation: Referred with progressive right thoracic scoliosis, initially observed with 25° curve 18 months ago, now 50° on follow-up X-rays Relevant history: No back pain, no neurological symptoms, no history of trauma or infection, premenarchal, healthy otherwise, family history of scoliosis (aunt had spinal fusion) Examination findings:

• Visible right thoracic rib prominence on forward bend (Adams test positive)
• Right shoulder higher than left
• Left waist crease more prominent than right
• No café-au-lait spots or axillary freckling
• No midline dimples, hairy patches, or skin abnormalities
• Full range of spinal motion
• Neurological examination completely normal (power 5/5, sensation intact, reflexes 2+ symmetrical)
• No limb length discrepancy
• No foot deformity

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Investigations Provided

Laboratory Results

Imaging

Image 1: Standing PA and Lateral Whole Spine Radiographs

Radiological features:

• Right thoracic curve with Cobb angle 50° (T5-T12)
• Apex at T8-9
• Curve pattern: Lenke 1 (main thoracic)
• Lumbar modifier: C (lumbar curve crosses CSVL)
• Thoracic sagittal modifier: N (normal kyphosis 10-40°)
• Risser sign: 1 (early ossification of iliac apophysis)
• Triradiate cartilage: Closed
• No congenital anomalies
• No significant coronal imbalance

Image 2: MRI Whole Spine (if obtained)

MRI indications in AIS (atypical features):

• Left thoracic curve (right-sided is typical)
• Juvenile onset (<10 years)
• Rapid progression (>1° per month)
• Abnormal neurological signs
• Male patient with AIS
• Significant pain
• Would obtain in this patient due to surgical planning

Questions & Model Answers

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Key Teaching Points

Pattern Recognition

This pattern suggests AIS requiring surgery:

• Adolescent female with thoracic scoliosis
• Risser 0-2 (significant growth remaining)
• Curve magnitude ≥45-50°
• Documented progression despite observation/bracing
• No underlying cause identified (idiopathic)
• Normal neurological examination

Red Flags for Non-Idiopathic Scoliosis:

Critical Management Points

1. Risser sign guides prognosis - Risser 0-1 has significant growth and progression risk
2. Lenke classification guides surgery - determines which curves to fuse
3. MRI is mandatory preoperatively - exclude intraspinal pathology
4. Neuromonitoring is mandatory - SSEP and MEP monitoring
5. LIV selection is critical - wrong choice leads to adding-on or imbalance
6. Balance over correction - a balanced spine is more important than maximal correction

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Common Examiner Follow-ups

Q: "Why not brace this patient?"

Bracing indications:

• Risser 0-2 with significant growth remaining
• Curve 25-45°
• Skeletally immature

This patient has a 50° curve - bracing will NOT reduce the curve, only potentially slow progression. With a curve this size, surgery is indicated. Bracing is for curves 25-45° in growing children to prevent progression to surgical threshold.

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Q: "What is the natural history of untreated AIS?"

Untreated 50° curves will progress throughout life, potentially causing:

• Cosmetic deterioration
• Chronic back pain
• Reduced pulmonary function (if thoracic curve increases)
• Reduced quality of life

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Q: "What about anterior surgery?"

Anterior spinal fusion (ASF) for AIS:

• Historically used for thoracolumbar/lumbar curves
• Advantages: Fewer levels fused, better correction in coronal plane
• Disadvantages: Thoracotomy/thoracoabdominal approach, pulmonary morbidity, chest tube, longer recovery

Modern Practice: Posterior-only surgery with pedicle screws achieves excellent correction for almost all curve types. Anterior surgery is rarely needed now with modern instrumentation.

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Q: "How do you decide the lowest instrumented vertebra?"

LIV Selection Criteria:

1. Stable vertebra - touched by CSVL
2. Neutral vertebra - no rotation
3. Horizontal on bending films - disc below should open symmetrically

For Lenke 1C curves, the LIV is typically L1-L3 depending on flexibility. Ending too proximally risks adding-on (curve progression below fusion). Ending too distally sacrifices lumbar motion unnecessarily.

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Related Topics

• Congenital Scoliosis
• Neuromuscular Scoliosis
• Scheuermann's Kyphosis
• Spinal Cord Injury
• Pedicle Screw Placement
• Spinal Fusion Techniques