Fig. 7.

The transversal section of the brace at the main thoracic region is shown in this figure a. The sequence b, c, d, and e shows the correction induced by the brace, while fitted, at the apical level of the main thoracic region for a right convex scoliosis. The orientation and shape of the pads facilitate local derotation, as shown in figure a. The right dorsal pad produces a main vector oriented from dorsal-lateral to ventral-medial direction. This main dorsal vector can be decomposed in two forces, one to medial (b’) and the other one to ventral (a’). The dorsal pad is closed enough to ventral in its anterior part to reach and still contact the middle axial line, providing lateral support enough. The ventral pad is oriented closest to the frontal plane and produces also a vector, which can be decomposed in two forces, one to dorsal (a) and a second to medial (b). The section of the brace at the frontal plane passing throughout the “middle axillar line” (yellow line) shows how the pad is still contacting the body on the right side but leaving room on the left side. The brace action (biomechanics) is explained by the final forces a–a’, forming a pair of forces for derotation, where a is a major force than a’, and b’, which produce the necessary right to left force for translation. While derotating to the left, the apical region will also translate to the left and at the same to the back coupled to the ribs (force b will be cancelled by this translation). Breathing mechanics will produce some dynamic reactive forces, increasing the three components a, a’, and b’, with the consequent expansion of non-contact areas. This expansion supposes an additional dynamic effect of derotation, reshaping the thorax, and fighting well against the morphological lordotization of the main thoracic region by increasing the sagittal diameter of the thorax