The first under-arm brace made from thermo-plastic material was constructed in the early 1970s.
It was constructed from thermo-plastic material, usually polyethylene with a Plastazot foam material lining.
Internally, it had derotation pads made from Plastazot, placed at the hump points.
It was made by taking a plaster cast from the patient's body. Its processing was symmetric, that is creating a mold with the child's dimensions, but with symmetry.
In modified BOSTON braces, named BOSTON-type, there were rear or frontal metal supports, extensions towards the shoulders or metal derotation pads.
Today in Europe, it is used minimally due to its insufficiency in comparison to other types of braces.