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Curve Patterns of King et al for Idiopathic Thoracic Scoliosis

Description

King et al developed a classification scheme for idiopathic thoracic and combined thoracolumbar scoliosis. It was based on the curves described by Moe and is used to help guide management including placement of Harrington rods. The authors are from the Twin Cities Scoliosis Center in Minneapolis and St. Paul, Minnesota.


Curve

Vertebra

Other Features

Type

S-shaped with both thoracic and lumbar curves

both curves cross midline, with lumbar curve larger than the thoracic curve on standing X-rays

flexibility index < 0

I

 

both curves cross midline, with lumbar curve smaller than or equal to the thoracic curve on standing X-rays

flexibility index >= 0

II

 

thoracic curve crosses midline but lumbar curve does not ("overhanging")

 

III

single long thoraco-lumbar curve

L5 centered over sacrum; L4 tilts into curve

 

IV

S-shaped primarily involving thoracic curve

T1 tilts into the convexity of upper curve; L2-L5 centered over sacrum

upper curve structural on bending

V

 

Flexibility index:

• The percent flexibility of the thoracic and lumbar curves are measured on maximum lateral bending.

• Subtracting the percent correction of the thoracic curve from the percent correction of the lumbar curve is termed the flexibility index.

 

Methods for determining the stability of vertebra (Figures 1 and 2, page 1303):

(1) The stable zone of Harrington is defined by parallel vertical lines drawn through the lumbosacral facets. Vertebral bodies sitting between the lines are in the stable zone.

(2) The vertebra most closely bisected (even if the vertebra is tilted) by the central sacral line is considered a stable vertebra (where the central sacral line is based on the a vertical line though the center of the sacrum that is perpendicular to a line connecting the iliac crests.

 


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