Purpose Bracing is indicated as nonoperative treatment for certain patients with adolescent idiopathic scoliosis (AIS). Scoliosis Research Society (SRS) criteria recommend bracing for patients with AIS when they have curves between 25° and 40°, are 10 years old or more, are in Risser stages 0, 1, or 2, and are premenarchal or less than 1 year after menarche. Recent studies have shown a number needed to treat (NNT) for scoliosis braces of 3-4, indicating that bracing changes the natural history in only 1 of every 3-4 patients. The Sanders Maturity Scale, based on a left hand radiograph, has been shown to be the best predictor of the curve acceleration phase of growth. The purpose of this study is to determine the correlation between the Risser and Sanders systems, and to determine if one system can be used to predict the stage of the other. Methods Females between ages 8 and 16 seen for evaluation for idiopathic scoliosis or spinal asymmetry in a single surgeon’s clinic over 1 year, and whose evaluation included a PA scoliosis X-Ray and a left hand X-Ray, were included. The main curve size, Risser stage (-1 to 5), and Sanders classification (1 to 8) were recorded for each encounter. Risser 0 with open triradiates was recorded as “Risser -1” and Risser 0 with closed triradiates was recorded as “Risser 0”. A scatter plot was generated, and the strength of association between the two sets of variables was analyzed using the Pearson correlation coefficient. The Brown-Forsyth test was used to evaluate the variance of Sanders stages at each Risser stage. Results 280 consecutive patients who met the inclusion criteria were included in the analysis. The Pearson correlation coefficient (R) between the Risser stage and the Sanders stage was 0.9125 (p < 0.00001). This strong correlation is not surprising, as both systems increase in value as patients become more mature. The Brown-Forsyth test for variability (F) at each Risser stage was 8.1332 (p=3.567), indicating that the variance of Sanders stages is significantly different at individual Risser stages. Conclusions When assessing skeletal maturity in idiopathic scoliosis patients, the individual Risser stage is a poor predictor of the Sanders stage of skeletal maturity. Considering that the Sanders Maturity Scale has been shown to be a more accurate predictor of the curve acceleration phase of growth, efforts to develop new bracing criteria based on the Sanders classification and decrease the number needed to treat are warranted.

Figure 1

Scatter plot with trendline for 280 patients.

Figure 1

Scatter plot with trendline for 280 patients.

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