This study was undertaken to investigate the relationship between the Risser sign and chronological age and menarche in elementary, middle, and high school students, and to investigate the reliability of the Risser sign.

We reviewed 1, 870 spine standing AP X-rays, which included the iliac crest. We tried to identify a correlationbetween the Risser stage and chronological age, and between Risser stage and menarche. In addition, we investigated inter-observer error in the determination of Risser stage.

The mean ages of Risser 1, 2, 3 and 4 female students were 12.9, 13.3, 13.6, and 14.3 years, and the mean ages of Risser 1, 2, 3 and 4 male students were 14.0, 14.3, 14.5, and 15.6 years (Spearman's rho=0.560, p<0.01). The mean menarchal age of female students were 12 years 4 months, which is 7 months earlier than the mean chronological age of Risser 1 in female students. Wefound that it takes 24 months to progress from menarche to iliac crest maturation (Risser 4) (Spearman's rho=0.571, p<0.01). The percentage of agreement in the determination of Risser stage by three orthopaedic surgeons was 73.3%, showing good reliability with a Kappa value of 0.739-0.783.