How is the severity of scoliosis classified by degree of curvature?

Scoliosis Severity Classification by Degree of Curvature

Scoliosis is classified by severity based on the Cobb angle measurement, with mild scoliosis defined as a curve of 10-25 degrees, moderate scoliosis as 25-40 degrees, and severe scoliosis as greater than 50 degrees requiring surgical intervention. 1, 2

Classification System

• Scoliosis is defined as a lateral spinal curvature with a Cobb angle of 10° or more 2
• The severity classification is based on the magnitude of the curve as measured by the Cobb method on standing radiographs 1
• The American College of Radiology recommends the following classification system:
  • Mild scoliosis: Cobb angle of 10-25 degrees 3, 4
  • Moderate scoliosis: Cobb angle of 25-40 degrees 3, 2
  • Severe scoliosis: Cobb angle greater than 40-50 degrees 5, 3

Clinical Implications of Different Severity Levels

• Mild scoliosis (10-25 degrees):

  • Usually asymptomatic with minimal cosmetic concerns 3
  • Requires monitoring with radiographs every 4-6 months in skeletally immature patients 2
  • Typically does not cause disability or functional impairment 3
  • May benefit from scoliosis-specific physical therapy to prevent progression 3

• Moderate scoliosis (25-40 degrees):

  • May benefit from bracing treatment, especially in skeletally immature patients 3, 4
  • Requires more vigilant monitoring for progression 6
  • May cause some cosmetic concerns and occasional back pain 7
  • Risk of progression is higher during periods of rapid growth 2

• Severe scoliosis (>40-50 degrees):

  • Surgical intervention is medically necessary for curves greater than 50 degrees 5
  • High risk of continued progression at approximately 1 degree per year even after skeletal maturity 5, 6
  • May lead to physical pain, cosmetic deformity, psychosocial distress, and potential cardiopulmonary complications 5, 3
  • Posterior spinal fusion with instrumentation is the standard surgical approach for curves of this magnitude 5

Risk Factors for Progression

• Skeletal immaturity (Risser stage 0-2) significantly increases the risk of curve progression 5, 4
• Female gender has a higher risk of progression, with a female-to-male ratio of 10:1 for larger curves (>40°) 6
• Curve location affects progression risk:
  • Thoracic and lumbar curves show higher sensitivity to progression than thoracolumbar curves 4
  • Left thoracic curves are considered atypical and may indicate underlying pathology 1

Red Flags Requiring Urgent Evaluation

• Rapid curve progression (>1° per month) 1
• Functionally disruptive pain 1
• Focal neurological findings 1
• Atypical curve patterns (left thoracic curve, short segment curve) 1
• Development of new neurological symptoms 6

Monitoring Recommendations

• Radiography is essential for definitive diagnosis, classification, and treatment planning 1
• Serial monitoring with radiographs is necessary for skeletally immature patients, with a recommended frequency of no more than once every 6 months 1
• After skeletal maturity, only curves greater than 30° require continued monitoring for progression 2
• Excessive radiation exposure should be avoided by following recommended monitoring intervals 6