What is the recommended X-ray (X-ray) protocol for evaluating scoliosis?

X-ray Protocol for Scoliosis Evaluation

Obtain upright posteroanterior (PA) and lateral radiographs of the complete spine (cervical, thoracic, and lumbar) as the primary imaging modality for diagnosing, classifying, and monitoring scoliosis. 1

Standard Radiographic Protocol

View Selection and Positioning

• PA views are mandatory over AP views to reduce breast radiation exposure, particularly important in the predominantly female adolescent population 1
• Both PA and lateral views must be obtained in the upright (standing) position to assess the complete spinal alignment under physiologic loading 1
• The radiographs must visualize the entire spine from cervical through lumbar regions to evaluate the full extent of curvature and compensatory curves 1

What to Measure and Document

• Cobb angle measurement to quantify lateral curvature (≥10° defines scoliosis) 1, 2
• Vertebral rotation using the Nash-Moe method 2
• Risser stage to assess skeletal maturity and predict progression risk 1
• Identify apex vertebra, end vertebrae, neutral vertebra, and stable vertebra 2
• Classify curve type as structural versus nonstructural, and primary versus compensatory 2

Critical Red Flags Requiring Additional Imaging

Patterns That Mandate MRI Evaluation

• Left thoracic or thoracolumbar curves are atypical for adolescent idiopathic scoliosis and warrant immediate MRI, as 2-4% of presumed idiopathic cases actually have neural axis abnormalities 1
• Short segment curves 3
• Rapid curve progression 3
• Functionally disruptive pain 3
• Focal neurological findings on examination 3
• Male sex (less common presentation) 3
• Absence of apical segment lordosis/kyphosis 3

Congenital Scoliosis: Non-Negotiable MRI Requirement

• All patients with congenital scoliosis require MRI of the complete spine before any treatment decision, as intraspinal anomalies occur in 21-43% of cases 4
• A normal neurological examination does NOT predict normal MRI—physical exam accuracy is only 62% for detecting intraspinal anomalies 4
• Intraspinal abnormalities include tethered cord, filar lipoma, syringohydromyelia, and diastematomyelia 1, 4

Serial Monitoring Frequency

Adolescent Idiopathic Scoliosis

• Risser stages 0-3: Limit radiographs to once every 12 months maximum 1
• Risser stages 4-5: Radiographs every 18 months are sufficient 1
• SOSORT guidelines suggest no more frequent than every 6 months for any serial follow-up 1

Congenital Scoliosis

• Serial PA radiographs every 6 months maximum to monitor progression 4
• Curves with unilateral bar and contralateral hemivertebra may progress >10° per year and require closer monitoring 4

Pre-Surgical Imaging Requirements

Mandatory Before Surgery

• MRI of the entire spine is mandatory before surgical intervention in all cases, as neural axis abnormalities occur in more than 20% of patients with severe curves 1
• This applies even with normal neurological examination 1, 4

CT for Surgical Planning

• CT spine should be obtained for surgical planning when surgery is being considered, as it reduces screw misplacement from 15.3% to 6.5% 4
• Use low-dose CT protocols when CT is necessary 3

Common Pitfalls to Avoid

• Never assume clinical examination alone can determine curve magnitude or progression—radiography is essential for accurate measurement 1
• Never skip MRI in congenital scoliosis regardless of normal neurological exam, as 21-43% have intraspinal anomalies that alter surgical planning 4
• Never dismiss left thoracic curves as typical idiopathic scoliosis—these require MRI evaluation to rule out neural axis pathology 1
• Never rely on physical examination to rule out intraspinal anomalies—exam accuracy is only 62% even in experienced hands 1, 4
• Right thoracic curves are the typical pattern for adolescent idiopathic scoliosis; any deviation from this pattern warrants investigation 1