Types of Foot Orthoses

What are the different types of foot orthotics (orthoses) and why do they work? There are three basic types of foot orthotics (orthoses): protective insoles, accommodative orthoses and functional orthoses.

Protective Insoles: Protective insoles supplement the soft tissue of the foot. Some of these devices are materials designed to provide shock absorption, while others are designed solely to provide supplemental cushion. As people age, the fat pad of the foot breaks down, often resulting in the sensation of 'walking on bone'. A cushion insole can protect the painful areas of the foot during ambulation (walking / running) and prevent long-term skin breakdown. Protective insoles can be purchased over-the-counter as 'ready to use' or they can be custom fitted in the podiatrist's office, where accommodations are added to a prefabricated insole to improve the fit of the device to the patient's foot.

Accommodative Orthoses: Accommodative orthoses adapt or 'accommodate' to the foot structure. The materials used in construction of the device determine whether the device provides support, cushion, protection or a mixture of the three. These materials have various qualities such as shock absorption, memory (prevents material from deforming under the patient's body weight), thermogenicity (ability to maintain heat or to disperse heat), and conformation (how well the material conforms to the foot).

Accommodative devices, like protective insoles, can be purchased over-the-counter as 'ready to wear', they can be custom fitted in the podiatrist's office, or they can be custom made. Custom made devices are usually manufactured from a plaster cast of the foot or directly molded to the foot by methods such as 'thermolding' wherein the orthotic is shaped to the foot after the material is heated to improve its malleability. Accommodative devices are often used in the treatment of diabetic ulcers, rheumatoid arthritis, neuropathy (loss of sensation), and peripheral vascular disease.

Functional Orthoses: Functional orthoses attempt to control the motion of the foot, either to prevent excess motion or provide motion. Merton Root, an expert in the field of biomechanics, states the purpose of the functional orthotic is to assist in controlling foot geometry and force directions by reducing the need for muscles to compensate or joints not staying in their more stable positions' [2]. When a joint does not function in its more stable position and muscles are made to compensate, pain results, whether immediately (acutely) or over the long term (chronically). Well-known examples of these painful results include tendonitis, arthritis, bone spurs, shin splits, and muscle spasms [3].

There are many types of functional orthotic devices, several bearing the name of the designer. These devices are usually custom made from a plaster cast of the foot taken in the podiatrist's office. The extensive steps in the fabrication of these devices contribute to the total expense. Functional orthoses are often used in the treatment of mechanical imbalances, foot deformities caused by cerebral palsy or other neurological conditions, pronation syndrome (excessive flattening of the arch), hallux limitus (limited motion at the big toe), plantar fasciitis (heel spur syndrome), and hallux abducto-valgus (bunion deformity). Specialized functional devices devices can be constructed to counteract marked pronatory forces encountered in running (Blake device) or to provide accommodative along with functional control in specific sport conditions. Devices can be custom made for the ballet dancer who is en pointe or for the runner who has been diagnosed with over-pronation or pronation syndrome.