During midstance, the ankle and heel are misaligned, and your foot has no arch. At heel contact, orthoses limit the swing of your heel so your heel strikes the ground correctly.
Excessive motion is controlled.
They're typically made with comfortable thermoplastic materials, which are guaranteed to last for years, and can be designed to fit in dress shoes, athletic shoes, boots, and skates. As you walk your heel swings from side to side very slightly, like the pendulum on a clock. If, however, your heel swings too far when you walk or run, your foot may be overpronating, or flattening too much. This incorrect movement stresses and weakens parts of your foot. Over time, you may develop symptoms in your feet ranging from a change in shape to pain when you walk.