I recently worked with a young girl with cerebral palsy that was causing right side paralysis and jerky athetoid movements.
When walking she would veer to one side and her legs would scissor (cross over) excessively.
By using a thigh brace she was able to walk in a fairly straight line with considerably reduced leg scissoring.
She told me she felt more balanced and I could see how much more confident her movement was.
The role of the brace is to provide extra stability. That, together with a program of strengthening exercises, may enable her improved movement to become permanent.