Risser staging system

Last revised by Leonardo Lustosa on 26 Feb 2024

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 potential, which 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

French Risser classification
  • stage 0: no ossification center at the level of iliac crest apophysis

  • stage 1: apophysis under 33% of the iliac crest

  • stage 2: apophysis over 33-66% of the iliac crest

  • stage 3: apophysis over >66% of the iliac crest

  • stage 4: complete ossification of the iliac crest

  • stage 5: complete 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 3:

  • 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

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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