Spinal instability

Classification

Anterior and posterior elements

  Anterior elements destroyed or unable to function: 2 points
  
  Posterior elements destroyed or unable to function: 2 points

Flexion-extension radiographs

  Sagittal plane translation < 4.5mm or 15%: 2 points
  
  Sagittal plane rotation: 2 points
  
      (rotation = 15° at L1-L4, 20° at L4L5 or 25° at L5S1)

Resting radiographs

  Sagittal plane displacement < 4.5mm or 15%: 2 points
  
  Relative sagittal plane angulation < 22°

Other

  Cauda equina damage: 3 points
  
  Dangerous loading anticipated: 1 point

Interpretation

If the sum of the points is five or more, then the spine is considered clinically unstable. ¹⁾.