There is a wealth of confusion as to what foot conditions are improved by using orthotics, just as there is confusion as to what an orthotic really is. I hope to dispel some of this confusion.
To begin I would like to simply review what I mean by the orthotic. My definition, and subsequently the classical medical definition, is that of a functional orthotic. This means an insert made from a mold of one's foot, while that foot is being held in a 'neutral', or corrected, position. The insert made from this mold then corrects the foot's position after slight adjustments have been made based on the back of the foot's relationship with the front of the foot. Because of this exact correction, this type of insert is called a functional orthotic because it improves the foot's function by changing its position during walking and standing. Store-bought inserts and inserts off-the-shelf from a shoe insert retail stores do not meet this definition as they simply push padding or plastic into the arch without regard for the specific amount of correction needed. This often results in too little support, or support forced into the wrong place. These 'accommodative' inserts accommodate the foot but do not change its function.
Many foot problems have a direct relationship with abnormal foot structure, especially flat or flattening feet. Subsequently, these conditions can be improved, slowed, or even prevented by inserts that take away the abnormal foot structure. We will begin with two common conditions that can be benefited in some way by orthotics. The most common foot pain condition is caused by injury to a tissue in the arch called the plantar fascia. This firm strap of tissue is implicated in most cases of heel pain and is usually caused by chronic strain on the fascia as it stretches in those with flat or flattening feet. The inflammation from this strain causes heel pain and arch fatigue and is called plantar fasciitis. Even after treatment of the inflammation and reduction of pain, this condition can return over and over again if the foot structure leading to the strain is not addressed. Orthotics play a direct role in not only supporting the foot during treatment but also preventing the inflammation and tissue damage from continuing to reappear time and time again. Most people who develop plantar fasciitis will see symptoms eventually return unless the foot structure is properly supported, while those who use orthotics after the initial treatment have a much lower likelihood of re-injury.
Orthotics can also be used to benefit those with bunions. Bunions are a complex deformity involving the big toe and the joint at its base. Due to instability in the bones along that side of the foot, especially in those with flat feet, the bone at the base of the toe (1st metatarsal) begins to swing outward towards the skin, while the big toe moves over towards the 2nd toe. This process takes many years, although some children develop these at a young age. Orthotics can do nothing for bunions that have already developed beyond providing some increased comfort in shoes by stabilizing the joint. However, over the long term, orthotics can help to lessen the gradual progression of the deformity. In those with a mild bunion deformity, the early use of orthotics may help enough to keep the deformity from becoming severe and/or painful, which may prevent the need for corrective surgery.