Risser divided the steps of ossification and fusion of the iliac apophysis into six stages (Risser Stages 0–5), with the higher numbers describing advancement toward skeletal maturity. Stage 0 describes an x-ray on which no ossification center is seen in the apophysis, whereas Stage 5 represents complete ossification and fusion of the iliac apophysis. Two slightly different versions of the Risser system are in use; the differences concern Stages 2 to 4 [2, 3, 13]. The United States Risser staging system divides the excursion of the apophysis into quarters of the iliac crest beginning anterolaterally and progressing posteromedially (Fig. 1), whereas the French Risser staging system divides the excursion of the apophysis into thirds (Stages 1–3), with Stage 4 representing complete ossification and initiation of apophyseal fusion (Fig. 1). It is important to be aware of this difference when communicating Risser stages, as the French version will tend to stage apophyseal fusion by one less stage than the US system