A prescription foot orthosis is an in-shoe brace which is designed to correct for abnormal foot and lower extremity function (the lower extremity includes the foot, ankle, leg, knee, thigh and hip). In correcting abnormal foot and lower extremity function, the prescription foot orthosis reduces the strain on injured structures in the foot and lower extremity, allowing them to heal and become non-painful. In addition, prescription foot orthoses help prevent future problems from occurring in the foot and lower extremity by reducing abnormal or pathological forces acting on the foot and lower extremity. A prescription foot orthosis is more commonly known by the public as a "foot orthotic".
Podiatrists prescribe two main types of prescription foot orthoses for their patients, accommodative orthoses and functional foot orthoses. Both types of prescription foot orthoses are used to correct the foot plant of the patient so that the pain in their foot or lower extremity will improve so that normal activities can be resumed without pain. However, accommodative and functional foot orthoses are generally made using different materials and may not look or feel the same. Both types of prescription foot orthoses are nearly always prescribed as a pair to allow more normal function of both feet [similar to having both the left and right wheels of a car realigned in a front end alignment].