Risser staging system

Last revised by Henry Knipe on 28 Apr 2023

The Risser staging system is used to grade skeletal maturity based on the level of ossification and fusion of the iliac crest apophyses. It is used primarily in planning corrective surgery for scoliosis as a marker for skeletal maturity, which is a surrogate for growth velocity and growth potential, which in turn are important predictors of curve progression 3.

Classification

United States Risser staging system
  • stage 0: no ossification center at the level of iliac crest apophysis

  • stage 1: apophysis under 25% of the iliac crest

  • stage 2: apophysis over 25-50% of the iliac crest

  • stage 3: apophysis over 50-75% of the iliac crest

  • stage 4: apophysis over >75% of the iliac crest

  • stage 5: complete ossification and fusion of the iliac crest apophysis

As stage 0 and stage 5 can appear similar, age and long bone growth plates may be of help in discriminating between the two ref:

  • stage 0 patients will still have open growth plates in most of the long bones and will likely be younger than 16 years (female) or 18 years (male)

  • stage 5 patients will have no open growth plates in the long bones

French Risser classification

The French Risser staging system has stage 4 representing complete ossification and fusion and divides partial fusion into three thirds, with stages 1, 2, and 3 representing 0-33%, 33-66% and >66% of fusion, respectively ref.

History and etymology

The Risser sign (iliac aphosyseal fusion indicates vertebral growth completion) was first described in 1958 by Joseph C. Risser (1892–1982), an American orthopedic surgeon 3-5.

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Cases and figures

  • Figure 1
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  • Case 1: Risser stage 4
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  • Case 2: Risser stage 4
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  • Case 3: Risser stage 2
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