Neurosurgery notes/Spine/Deformity/Classification-Spinal deformity/Lenke classification

Lenke classification

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Status
Done
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Parent item
Classification-Spinal deformity

General

  • By Larry Lenke
  • Description (eg: 1B+)
    • Curve Type (1-6) +
    • Lumbar Spine Modifier (A, B, C) +
    • Thoracic Sagittal Modifier (, N, +)
  • Based on X-rays
      • Erect neutral (AP & lateral)
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      • Supine bending (left and right)
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Step 1: Identification of primary curve (Type 1-6)

  1. Coronal X-ray assessment
  1. Where is the curve?
      • Proximal thoracic (PT)
        • Apex at T3, T4, or T5
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      • Main thoracic (MT)
        • Apex between T6 ↔ T11/12 disc
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      • Thoracolumbar/lumbar (TL/L)
        • TL: Apex between T12 ↔ L1
        • L: Apex between L1/2 disc ↔ L4
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  1. Identify major curve
      • The biggest curve
      • Alway structural
      • Always either
        • MT (Type 1-4) OR
        • MT/L (Type 4*,5,6)
      • In Type 4 can be either MT or TL/L depending on which Cobb is larger
       
      notion image
  1. Identify minor curve
      • All other curves that are not major are minor curves
  1. Determine if minor curve is structural or not
      • Examine AP lateral bending X-rays
      • Definition of structural
        • > 25° in coronal plane on standing AP and do not bend out to < 25° on lateral bending films
        • OR > 20° in sagital plane
          • Proximal Thoracic
          Side Bending Cobb ≥ 25°
          T2-T5 Kyphosis ≥ +20°
          Main Thoracic
          Side Bending Cobb ≥ 25°
          T10-L2 Kyphosis ≥ +20°
          Thoracolumbar/Lumbar
          Side Bending Cobb ≥ 25°
          T10-L2 Kyphosis ≥ +20°
      • Example
          • Neural
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          Left lateral bend:
          • Structural
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          Right lateral bend:
          • Nonstructural
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  1. Assign Type 1-6 based on chart below 
      2. Curve Type
      PT**
      MT
      TL/L
      Curve Name
      Type 1
      Non structural
      Structural (major*)
      Non structural
      MT
      Type 2
      Structural
      Structural (major*)
      Non structural
      Double thoracic (DT)
      Type 3
      Non structural
      Structural (major*)
      Structural
      Double major (DM)
      Type 4
      Structural
      Structural (major*)
      Structural (major*)
      Triple major (TM)
      Type 5
      Non structural
      Non structural
      Structural (major*)
      TL/L
      Type 6
      Non structural
      Structural
      Structural (major*)
      TL/L-MT
      • **If PT is the largest curve, then by default assign major curve to MT

Step 2: Assignment of Lumbar modifiers (A,B,C)

  • Examine upright coronal x-ray.
  • Accept pelvic obliquity <2 cm.
    • If >2 cm, then must block out leg length inequality to level pelvis.
  • Assign modifier
      • A. If CSVL passes between pedicles of apical lumbar vertebrae (ALV)
        • CSVL falls between pedicles of the lumbar spine up to stable vertebra
      • B modifier if CSVL touches pedicle of apical lumbar vertebrae (ALV)
      • C modifier if CSVL does not touch apical lumbar vertebrae (ALV)
        • Apex of lumbar curve falls completely off the midline depicting a curve with complete apical translation off the CSVL
      • Tells where to start and stop fusion
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Step 3: Assignment of Sagittal thoracic modifier (-, N, +)

  • Measure sagittal Cobb from T5 to T12
  • Assign modifier
      • Hypokyphotic (-) if < 10°
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      • Normal if 10-40°
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      • Hyperkyphotic (+) if >40°
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  • Issues
    • The rotational deformity is not classified.
      • Work continues to find a truly 3D classification.
      • This classification is two- dimensional and addresses both the sagittal and the coronal plane.
    • These classification systems do not address the problems of which the patients complain— their cosmesis.
  • Difference vs Lenke classification
    • AdIS uses of supine radiographs instead of side-bending radiographs
      • Therefore the definition for Structural criteria is different
    • AdIS uses lumbosacral and global alignment modifers whereas Lenke uses lumbar spine modifiers
    • AdIS has a global alignment modifier vs Lenke does not have

Summary card

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