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Risser sign is defined by the amount of calcification present in
the iliac apophysis and measures the progressive ossification from
anterolaterally to posteromedially.
A Risser grade of 1 signifies up to 25 percent ossific ation of
the iliac apophysis, proceeding to grade 4, which signifies 100
percent ossification (Figure 1).
A Risser grade of 5 means the iliac apophysis has fused to the
iliac crest after 100 percent ossification. Children usually
progress from a Risser grade 1 to a grade 5 over a two-year period.
One study8 found that immature patients (Risser grades 0 and 1) with
a spinal curvature measuring 20 to 29 degrees had a 68 percent
probability of progression of 6 degrees or more during remaining
growth. Patients closer to maturity (Risser grades 2 to 4) and with
the same degree of scoliosis had a 23 percent probability of
progression.8 Curves measuring 5 to 19 degrees in immature patients
had a 22 percent probability of progression, while small curves in
mature patients had only a 1.6 percent probability of progression.8
Fig 1 Risser sign 
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