Orthotics are orthopaedic devices designed to treat or adjust various biomechanical foot disorders. When the foot is not functioning correctly, it will produce painful areas. The signs and symptoms of altered biomechanics of the foot are usually registered as pain. An orthotic can relieve that pain by supporting the ligaments and the osseous (bone) structures of the feet. There are several ways to construct an orthotic such as taking a plaster impression of the foot or using a foam based impression. The newer, more advanced way is to take an optical impression of the foot.

Orthotics are usually divided into four categories:

• Functional orthotics are designed with the primary goal of controlling an individual's biomechanics. They correct defects in the arch that cause poor shock absorption such as excessive pronation (flattening of the arch) and supination (a high arch) of the lower ankle or subtalar joint. Pronation is a complex movement involving eversion (turning out) of the heel and forefoot with a corresponding internal rotation (turning in) of the lower leg, and flattening of the arch. Supination is the opposite of it. Functional orthotics are fabricated over a model of one ?s foot to capture its individual characteristics like arch height, pressure points and bone size in order to correct injury-causing imbalances. They are usually made of rigid or semi-rigid material.


• Weight-dispersive or accommodative orthotics are designed with the aim of conforming to the individual ?s anatomy. They are usually designed for diabetic patients or people with arthritis, whose feet are more sensitive. They are made of soft materials at the expense of some control to prevent excessive pain and discomfort. These orthotics off-load areas of high pressure and allow the forces to be evenly distributed to the foot. The padding is designed to relieve pain and pressure on the metatarsal heads (pain in the sole of the foot), sesamoid bones (two oval bones under the big toe joint), collapsed tarsal bones, sores and chronically inflamed toes.


• Supportive orthotics are arch supports usually prescribed to treat problems of the plantar arch. The plantar arch starts at the heel bone and runs to the base of the toes. Arch pain occurs when this membrane becomes worn down due to constant strain caused by prolonged standing, walking or running. This causes pain in the arch of the foot and often in the heel. Supportive orthotics are commonly found in the form if insoles and help relieve pressure on toe deformities.


• Early childhood orthotics are special devices designed to correct biomechanical walking problems in young children. There are various stages in the development of a child's lower limbs which may sometimes include being slightly flat-footed, in-toed, bow-legged or knock-kneed for a time. Orthotics are used to realign the arch structure, realign in-toeing and out-toeing gait problems, or to accommodate knee and hip problems. They include splints, gait plates and night bars - devices used to hold a child's feet and legs at a proper angle while sleeping, thus promoting corrective adjustment for excessive toe-in or toe-out walking.

Some people develop discomfort in the foot, leg, or lower back when they first start to wear orthotics. This is normal and is due to a realignment of the whole lower extremity and pelvis. Muscles and ligaments have to readjust to this new alignment. When they do the discomfort disappears.