The concertina effect of brace correction. The concertina effect  could explain the importance of patient's compliance. According to this hypothesis, each time a brace is weaned the deformity gradually moves back from the maximal in-brace correction to the original out-of-brace situation; this reversal is due to a postural collapse [39–41], that is correlated to the length of brace weaning and the rigidity (flexibility) of the spine  (itself correlated to the stage of growth, the bone age, the muscular endurance and the usual brace wearing). According to the "concertina effect" hypothesis, the deformity reached at the end of daily brace weaning gives the allowed compression of the wedged vertebrae, and consequently the final results. In fact, the more the brace is weaned daily, the worst the results. We published some preliminary proves of this hypothesis .