Orthoses, or orthotic devices, are shoe inserts that are intended to adjust an abnormal, or irregular, walking pattern. Orthoses are not truly or solely "arch supports," though some people use those words to describe them, and they perhaps can best be understood with those words in mind. They perform functions that make standing, walking, and running more comfortable and efficient, by altering the angles at which the foot strikes a walking or running surface.
Doctors of podiatric medicine prescribe the use of orthoses as conservative approaches to many foot problems; their use is a highly successful, practical treatment form.
Orthoses take various forms and are constructed of various materials. All are concerned with improving foot function and minimizing stress forces that could ultimately cause foot deformity and pain.
Foot orthoses fall into three broad categories: those that primarily attempt to change foot function, those that are primarily protective in nature, and those that combine functional control and protection.
The so-called rigid orthotic device, designed to control function, may be made of a firm material such as plastic, and is used primarily for walking or dress shoes. It is generally fabricated from a mold of the individual foot. The finished device normally extends along the sole of the heel to the ball or toes of the foot. It is worn mostly in closed shoes with a heel height under two inches. Because of the nature of the materials involved, very little alteration in shoe size is necessary.
Rigid orthoses are chiefly designed to control motion in two major joint complexes of the foot, which lie directly below the ankle joint. These devices are long lasting, do not change shape, and are usually unbreakable. Strains, aches, and pains in the legs, thighs, and lower back may be due to abnormal function of the foot, or a slight difference in the length of the legs. In such cases, orthoses may improve or eliminate these symptoms, which may seem only remotely connected to foot function.
The second, or soft, orthotic device helps to absorb shock, increase balance, and take pressure off uncomfortable or sore spots. It is usually constructed of soft, compressible materials, and may be molded by the action of the foot in walking or fashioned over a plaster impression of the foot. Also worn against the sole of the foot, it usually extends from the heel past the ball of the foot to include the toes.
The advantage of any soft orthotic device is that it may be easily adjusted to changing weight-bearing forces. The disadvantage is that it must be periodically replaced. It is particularly effective for arthritic and grossly deformed feet where there is a loss of protective fatty tissue on the side of the foot. It is also widely used in the care of the diabetic foot. Because it is compressible, the soft orthosis is usually bulkier and may well require extra room in shoes.
The third type of orthotic device (semirigid) provides for dynamic balance of the foot while walking or participating in sports. This orthosis is not a crutch, but an aid to the athlete. Each sport has its own demand and each sport orthosis needs to be constructed appropriately with the sport and the athlete taken into consideration. This functional dynamic orthosis helps guide the foot through proper functions, allowing the muscles and tendons to perform more efficiently. The classic, semirigid orthosis is constructed by using laminations of leather and cork, reinforced by a material called silastic.
Orthotic devices are effective in the treatment of children with foot deformities. Most podiatrists recommend that children with such deformities be placed in orthoses soon after they start walking, to stabilize the foot. The devices can be placed directly into a standard shoe, or an athletic shoe.
Usually, the orthoses need to be replaced when the child's foot has grown two sizes. Different types of orthoses may be needed as the child's foot develops, and changes shape.
The length of time a child needs orthoses varies considerably, depending on the seriousness of the deformity and how soon treatment is initiated.
Various other orthoses may be used for multidirectional sports or edge-control sports by casting the foot within the ski boot or ice skate boot or roller skate boot. Combinations of semiflexible material and soft material to accommodate painful areas are utilized for specific problems.