Neurosurgery notes/Spine/Deformity/Thoracic and lumbar deformity/Scoliosis/Paediatric Idiopathic scoliosis/Late onset idiopathic scoliosis (LOIS)/Suk Classification

Suk Classification

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Late onset idiopathic scoliosis (LOIS)
  • General
    • Suk et al. hypothesised that derotation manoeuvres might bring cephalad vertebrae into the stable zone, allowing shorter fusions
    • Help to identify if reducing one level of fixation from L4 to L3 for LOIS is possible
    • Pedicle screw fixation + improved three-dimensional deformity correction with rod derotation and DVR allows for shortening of the distal fusion level by 1 → allowing for preservation of more lumbar motion levels
    • PSY: Suk is trying to redistribute the rotation deformity so each vertebrae within the scoliotic curve. i.e. more proximal and distal vertebrae takes on more rotation to compensate for the natural (pre-corrected) rotation of the apical vertebrae. This might mean making the naturally mild rotated vertebrae more rotated. In certain situations (when there is a lumbar curve), suk suggests to worsen the rotation of the lower neutral vertebrae so that the lumbar curve can be reduced.
  • In some cases, Suk's criteria for Type A can be softened as follows:
    • The fusion can still stop at L3 when the L3-4 disc becomes parallel or closes towards the other side in the lumbar bending XR AND
    • In the same bending XR L3 does not cross the midline but becomes horizontal in line with the sacrum AND
    • Rotation is less than Nash-Moe 2 in the opposite lumbar bending XR.
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NV neutral vertebra, EV end vertebra, CSL central sacral line, DM Double Major, Gr II Grade 2 Nash and Moe classification, DVR Direct vertebral rotation
NV neutral vertebra, EV end vertebra, CSL central sacral line, DM Double Major, Gr II Grade 2 Nash and Moe classification, DVR Direct vertebral rotation
Nash and moe classification
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  • Classification
      • Single thoracic curve
      • Definition
        • A thoracic curve > 40, that is larger than the lumbar curve.
          • If the lumbar curve is more than 40,
            • The thoracic curve must be larger than the lumbar curve AND
            • The apical vertebra rotation of the lumbar spine should be less than Nash-Moe grade II.
      • Tx:
        • Selective thoracic fusion
          • i.e. A fusion between the proximal NV ↔ distal NV
          • Depending on the relationship between the NV and EV
            • Type A:
              • When the preoperative EV and the NV show no more than one-level gap difference or are the same
              • Fused down to the NV.
                • If the NV is same as the EV,
                  • Fusion can be stopped at the EV.
            • Type B:
              • If the NV is located 2–3 levels more distally than the EV
              • Fusion must go down one more level distally than type A or NV-1.
      Double thoracic curve
      • The double thoracic curve pattern that needs fusion of both the proximal and the distal thoracic curves is redefined as follows:
        • Idiopathic thoracic scoliosis AND
        • A distal thoracic curve of > 40, AND
        • A proximal thoracic curve of > 30, AND
        • Level or elevated left shoulder AND
        • T1 tilted.
      • The distal fusion levels are same as in the single thoracic curve, depend on whether type A or B.
      Double major curve
      • Define:
        • The lumbar curve is larger than the thoracic curve, AND
        • The lumbar curve is > 40 AND
        • The thoracic curve is > 30; AND
          • The thoracic curve is less than 5 larger than the lumbar curve AND
        • The apical vertebra rotation of the lumbar is more than grade II.
      • Treatment
        • Both the thoracic and the lumbar curves have to be fused.
          • LIV:
            • Type A curve:
              • Definition
                • L3 crosses the central sacral vertical line (CSVL) in right bending AND
                • L3 rotation is less than grade II in left bending
              • LIV: EV which is L3.
            • Type B curve:
              • Definition
                • L3 does not cross the CSVL in right bending AND
                • L3 rotation is more than grade II in left bending
              • LIV:
                • Fuse to the EV + 1 which is L4.
              The below is a flow diagram to help decide for lumbar curves if they need to have L3 or L4 LIV
              notion image
      Thoracolumbar and lumbar (TL and L) curve
      • Definition
        • A curve that is more than 40 AND
        • The thoracic curve < 30.
      • Treatment
        • The TL and L curve only needs to be fused.
          • LIV:
            • Type A curve:
              • Definition
                • L3 crosses the central sacral vertical line (CSVL) in right bending AND
                • L3 rotation is less than grade II in left bending
              • LIV: EV which is L3.
            • Type B curve:
              • Definition
                • L3 does not cross the CSVL in right bending AND
                • L3 rotation is more than grade II in left bending
              • LIV:
                • Fuse to the EV + 1 which is L4.
              The below is a flow diagram to help decide for lumbar curves if they need to have L3 or L4 LIV
              notion image