orthotics

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Orthotics is an allied health profession that is concerned with the design, development, fitting and manufacturing of orthoses, which are devices that support or correct musculoskeletal deformities and/or abnormalities of the human body.

The term is derived from "ortho", meaning to straighten. Sciences such as materials engineering, gait analysis, anatomy and physiology, and psychology contribute to the work done by orthotists, professionals engaged in the field of orthotics. Individuals who benefit from a complex orthosis may have an orthopedic condition such as scoliosis or a fracture or have sustained a physical impairment from a stroke or spinal cord injury, or a congenital abnormality such as spina bifida or cerebral palsy.

The word orthotic (plural orthotics) is often used as an adjective ("an orthotic insole") or noun ("an orthotic") to describe or name a foot-supporting device or insole, or a more complex device to control joint motion. Use of the word in this sense can be considered ungrammatical but is customary; orthosis (plural orthoses) is considered more grammatical.

Some devices are custom-made for a specific patient; off-the-peg orthoses are made to suit normal feet, and can be obtained through pharmacies, medical clinics, hospitals, athletic trainers, etc.

Differing orthoses may directly support the lower limb, upper extremity, or the spine. Orthotics proper involves devices made by technicians and fitted to the patient usually by a specialist in foot health such as pedorthist, orthotist, podiatrist, or chiropodist.

A pedorthist, for example, is a professional who works by prescription from a physician to ensure the proper application of an orthosis to an individual who might benefit from the orthosis—this is essentially the practice of orthotics.

Care in the 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. Some jurisdictions require professionals engaged in orthotics or those manufacturing and fitting orthoses to be licensed.

Benefits

The following information has to do most directly with foot orthoses and shoe inserts, referred to here as "orthotics."

In addition to providing relief for painful foot problems or an injury, people who walk or stand for long periods can benefit from orthotics. In sports orthotics will often increase endurance, performance and strength^{[citation needed]}. For overweight individuals, orthotics can help to counteract the extra stress on the feet, as minor problems are often exacerbated by weight.

Orthotics are particularly effective in relieving foot fatigue and discomfort experienced by older people who have developed arthritis in their feet. Orthotics may also be prescribed for children who have a foot deformity.

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 cause injury with the extra stress of sports activity. By eliminating the need for 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.

Structure and function

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 positions 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 like EVA Ethylene-Vinyl Acetate in different hardness values. 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. Lately multilayered and combined density and hardness EVA Ethylene-Vinyl Acetate devices are very popular in combination with CAD/CAM systems for the design of the orthotics, being designed on special purpose design software programs (CAD) and milled on Cnc_milling machines.

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.

Proprioceptive orthotics

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 (Rothbarts Foot) 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,

Foot Orthoses (orthotics)

Since feet are the major weight-bearing part of the body, foot pain is common; half of the Americans polled by the American Podiatric Medical Association had missed a day of work because of foot problems^{[citation needed]}. The foot contains 26 bones, up to 2 sesamoid bones, and many small structures which support and balance the weight of the entire body. Walking puts up to 1.5 times one's body weight on the foot^{[citation needed]}, and humans walk an average of 1,000 miles per year^{[citation needed]}.

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. Pedorthists, Osteopaths, Podiatrists, Chiropractors, physical therapists and sports medicine practitioners will often recommend custom foot orthoses as part of a treatment regimen.

They are prescribed to:

• Reduce the symptoms associated with many foot related pathologies.
• Provide support
• Accommodate foot deformity
• Provide better positioning
• Relieve pressure on a certain area of the foot
• Improve the overall biomechanical function of the foot and lower extremity

References

• Positano, Rock. "http://www.hss.edu/conditions_14431.asp Prescription Orthotics Can Help You Put Your Best Foot Forward]" 12 Oct 2004.

External links

• Theory and Practice Combine for Custom Orthotics