Scoliosis, the medical condition of having a sideways-curved spine in the shape of a C or an S, affects about 3.5% to 5% of adolescents in Hong Kong and China. About 20% of sufferers experience progressive curvature that requires them to wear braces or undergo surgery. Onset is observed in most patients between the ages 10 and 17, and females are eight times more likely than males to progress to a curvature that needs treatment.