The term is derived from the "ortho", meaning to straighten. Sciences such as materials engineering, gait analysis, anatomy and physiology, and psychology contribute to the work done by orthotists, the professionals engaged in the field of orthotics. Individuals who benefit from a complex orthosis may have sustained a physical impairment such as a stroke, spinal cord injury, or a congenital abnormality such as spina bifida or a developmental disability such as cerebral palsy.
Simpler foot orthotics allow the muscles, tendons and bones of the feet and lower legs to function at their highest potential. When appropriately prescribed, orthotics can decrease pain, not only in the foot, but in other parts of the body such as the knee, hip and lower back. They can also increase stability in an unstable joint, prevent a deformed foot from developing additional problems, and improve overall quality of life.
More recently, the term cognitive orthotics has been applied to assistive technology to correct cognitive functions.
Different orthoses directly support the knee, back, hip, and the upper extremity. They are manufactured by specialized technicians and fitted to the patient by orthotists. The orthotist generally works by prescription. Some prefabricated orthoses can be found in a pharmacy. Some prefabricated orthoses, or supports, are soft and can be purchased as a retail item. Care in proper fit of any device that applies force to the body must be taken to ensure good results and to prevent unwanted problems from an orthosis that is too tight or otherwise uncomfortable.
Sophisticated custom orthoses to more rigidly support compromised joints, weak muscles, and other medical conditions are often provided by orthotists. Plastic vs. metal and leather fitting, complex mechanical hinges, and fasteners to keep the orthosis affixed well to the portion of the body that the orthosis supports are a part of the process in delivering orthotic support.
In athletic individuals, sports activities result in a great deal of movement and pressure on the foot. Slight imbalances in the foot that are not harmful or even detectable under usual circumstances may make one more vulnerable to injury with the extra stress of sports activity. By eliminating the need for one's muscles to compensate for imperceptible imbalances, orthotics can reduce fatigue and promote efficient muscle function to enhance performance. With enough functional correction, the foot structure can be aligned to give more propulsion, making walking, running and cycling more mechanically efficient. In August 2008 it was reported that New York Giants wide receiver Plaxico Burress uses orthotics to correct conditions in both of his feet.
Foot orthotics take various forms and are constructed of various materials. All have the goal of improving foot function and minimizing stress forces that could ultimately cause foot deformity and pain. There are three broad categories of orthotics: those that primarily attempt to change foot function, those that are mainly protective or accommodative in nature, and those that combine functional control and accommodation. While orthotics can be made by several different processes, most orthotists make a plaster mold of the patient's foot and send it to a laboratory with a prescription. At the lab, technicians pour plaster into the mold, and when it hardens; it exactly reproduces the bottom of the individual's foot, although it is common for labs to "cast correct" by partially filling in the arch. This decreases the arch height of the orthotic and is done for comfort reasons. Once a reproduction of the individual’s foot is made, the technicians then use the orthotist's prescription to custom-make a device to meet the patient's specific needs. This process was first advocated by Root et al in the late 1970s and remains the preeminent standard despite the lack of significant, credible research demonstrating any improvement in foot function. It is based on the neutral position model of correction.
A completely different theoretical model and orthotic design has been advocated by Edward Glaser, DPM since 1992. In this model, the goal is to restore optimal arch height and function, since it is loss of arch height that is the most common factor behind foot pain and deformity. In order to capture the optimal amount of arch for any given foot, casting is done against the ground, sequentially and semi-weight bearing in foam. The orthotic is then made to match the exact shape of the foot with the rigidity calibrated to be able to hold the arch up with activity and yet flex slightly for comfort and functional pronation. It is based on the MASS (Maximum Arch Subtalar Supination) position model of correction.
Rigid orthotic devices are designed to control foot function, and may be made from a firm material such as plastic or carbon fiber. These types of orthotics are mainly designed to control motion in two major foot joints, which lie directly below the ankle joint. This type of orthotic is often used to improve or eliminate pain in the legs, thighs and lower back due to abnormal function of the foot. An example is an ankle-foot orthosis (AFO), used to treat foot drop. The AFO is molded to the lower part of a person's leg. A velcro strap fastens the AFO to the shin, and the patient's shoe (or an additional velcro strap) secures it to their foot. The AFO postions the lower leg based on the direction of the physician.
Soft orthotic devices help to attenuate shock, improve balance and take pressure off uncomfortable or sore spots. They are usually made of soft, compressible materials. This type of orthotic is effective for arthritis or deformities where there is a loss of protective fatty tissue on the side of the foot. They are also helpful for people with diabetes.
Semirigid orthotic devices are often used to treat athletes. It allows for dynamic balance of the foot while running or participating in sports. By guiding the foot through proper functions, it allows the muscles and tendons to perform more efficiently. It is constructed of layers of soft materials, reinforced with more rigid materials.
Calibrated orthotic devices are those based on the correction model and manufacturing technique advocated by Glaser (MASS position). It factors in the individual's body weight, foot flexibility and activity level to deliver a custom calibrated level of support that delivers firm but comfortable functional control while maintaining the properties of an accommodative device.
While most conventional orthotics relies on passively supporting and immobilizing the feet, proprioceptive orthotics is a new type of less costly orthotics that relies on the proprioceptive system. The proprioceptive system is the brain processing mechanical stresses received from nerve endings in the skin, joints, ligaments, tendons and muscles and providing motor output to control (tense and relax) muscles to maintain body equilibrium and intended motion. A proprioceptive approach to orthotics is particularly suited for people who have Morton’s Foot Syndrome or an elevated first metatarsal (usually, but not necessarily associated with MFS). Morton’s Foot Syndrome is characterized by a deeper cut web space between the first and second toe and/or a longer appearing second (Morton’s) toe. Morton’s Foot Syndrome is also defined to include a hyper mobile first metatarsal and is often associated with calluses underneath the 2nd and 3rd metatarsals (Morton). An elevated first metatarsal is characterized by the first metatarsal not being weight bearing when the weight bearing foot is positioned in its subtalar neutral position (where the heel bone is perpendicular to the floor). This can be observed by mapping the pressures underneath the sole of the foot. It is thought (Rothbart) that this condition is associated with retention in talar torsion (a structural variation) as described by (Sewell) who documented that a talar head rotation in the frontal plane may vary by as much as 20 degrees from person to person. The result is that in “normal subjects” the first metatarsal does not become fully weight bearing until 88% of the contact stance phase of gait is complete (Cornwall, McPoil), causing the foot to substantially hyperpronate through mid-stance and most of the propulsion cycle. The theory behind proprioceptive orthotics revolves around the natural response of the foot and body in response to how the ground is felt by the feet. Travell and Simons stated that Morton’s Foot Syndrome causes an unstable foot where the main pressures are focused on the heel and at the area at the base of the second toe causing walking (presumably because the associated elevated first metatarsal) to be akin to walking in ice skates. This instability by all appearances causes one of two different proprioceptive responses. The foot is either freely released to roll in (hyperpronators = inside outsole shoe wear), or this action is partially or fully resisted through bracing the muscles to prevent it by forced (conscious or subconscious) supination (outside outsole wear). Since supination is most often a proprioceptive response (compensatory response) to hyperpronation, hence supinators are typically hyperpronators in disguise. Proprioceptive insoles are designed to alter how the foot feels the ground, particularly the timing of the first metatarsal ground contact. When ground contact is felt underneath the first metatarsal, muscles are naturally activated to push against the ground forces. When the ground is purposefully elevated underneath the first metatarsal, this muscle response is thought to happen sooner hence bringing the first metatarsal to bear more weight earlier in the contact gait cycle and stabilizing the forefoot. This controls hyperpronation, and, as a result, natural proprioception reduces the subconscious urge to compensate by supinating the foot. Proprioceptive orthotics may therefore be applied to eliminate or reduce both foot and general postural musculoskeletal pain in both hyperpronators and supinators. Proprioceptive orthotics may be combined with passive arch support in cases of severe hyper mobility, and temporarily while healing Plantar Fasciitis injury. Because proprioceptive orthotics only requires small dimensions to influence the neuromuscular system, they are thin, flexible and virtually unnoticeable in footwear. The foot remains free to move naturally and comfortably.
Foot pain is not normal and should not be ignored; problems can affect the functioning of other parts of the body, including the hips, knees, and back. These are foot-related problems that may be related to biomechanical issues. Podiatrists, physical therapists and sports medicine practitioners will often recommend custom foot orthoses as part of a treatment regimen.
They are prescribed to: