Sample Size and Analysis: The null hypothesis for the primary analysis is that the brace is less effective than casting by at least five percentage points on the ASKp scale. Assuming a standard deviation of 10%, alpha = 0.05, beta = 0.2 and 10% dropout rate yields a sample size of 112 patients. Secondary analyses will include Fisher's Exact test to compare proportions of children with full range of motion of the injured ankle at four weeks and with full baseline activity level at four months, and the area under the curve of a pain-time profile curve will be compared using a Student's t-test. An economic analysis will assess the incremental net benefit of bracing versus casting from a health care perspective.