Orthotic treatment may be effective in repositioning a mobile flat foot and then to hold it in a corrected position.
The effect is only present when the orthotic is worn in the shoe and ceases if it is not worn. Whatever the cause of the flat foot, the techniques used will be essentially the same. These are to resupport the arch with a rigid plastic arch , and to reposition the heel by placing a "wedge" under its inner side to tilt it and a heel cup to hold it. Whether orthotic treatment prevents the progression of a deformity is not definitively known, but from basic principles there is no reason why it should not.
In the flexible flat foot, orthotics are usually the recommended first line of treatment. In a rigid and arthritic flat foot orthotics cannot correct the foot position but they may be able to improve symptoms.