Ankle-foot orthoses (AFOs) are orthoses or braces, usually plastic, encompassing the ankle joint and all or part of the foot. AFOs are externally applied, and are intended to control position and motion of the ankle, compensate for weakness, or correct deformities.[1] They control the ankle directly, and can be designed to control the knee joint indirectly as well.[1]
AFOs are commonly used in the treatment of disorders that affect muscle function such as stroke, spinal cord injury, muscular dystrophy, cerebral palsy, polio and multiple sclerosis. AFOs can be used to provide support to weak or wasted limbs or to position a limb with tight, contracted muscles into a more normal position. They are also used to immobilize the ankle and lower leg in the presence of arthritis or fracture, and to correct foot drop. An AFO may also be referred to as a foot-drop brace.
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Background
Ankle foot orthoses are the most commonly used orthoses, making up about 26% of all orthoses provided in the United States.[2] According to a review of Medicare payment data from 2001 to 2006, the base cost of an AFO was around $500 – $700.[3] An AFO is generally constructed of lightweight polypropylene-based plastic in the shape of an "L", with the upright portion behind the calf and the lower portion running under the foot. They are attached to the calf with a strap, and are made to fit inside accommodative shoes. The unbroken "L" shape of some designs provides rigidity while other designs with a jointed ankle provide different types of control.
The use of generic descriptions of orthopedic braces, such as ankle foot orthosis, began in the late 1970s as the result of work done by the American Academy of Orthopedic Surgeon in order to make classification of such braces easy. The initial description in the literature of the device now referred to as an ankle foot orthosis was made by York, et al., in the late 1960s. Prior to that time, braces that supported the lower leg were limited to metal and leather designs attached to the shoe or plaster casts, called short leg braces or short leg casts.
The term AFO now also refers to what are generically called "multi podus boots". This term belongs to RCAI, the inventor of the now expired patent. These boots are complete orthotics with stronger plastic shells. KYDEX is the preferred thermoplastic. Soft, padded "softgoods" cover the plastic; Cure-BAN anti-microbial impregnated softgoods protect and promote skin care; again, hook and loop closures are used to attach the device around the calf and possibly the foot. Heel float, ankle-foot contracture and various neurological conditions respond well to this type product. Fast-LOK ambulation pads are an option as well as anti-rotation bars and toe posts to protect the toes.
Historically, custom made orthopedic boots provided rigid bracing within the lining of boots creating a rigid AFO or supra malleolus bracing component between the linings. Examples of these boots are on display at different shoe museums worldwide. Currently, carbon fibers and Kevlar have replaced leather, glues and fibre board for the bracing components. The soles are constructed with custom roll and wedges to assist with ambulation and stability throughout the gait cycle. These boots are currently referred to as custom made orthopedic brace boots or ambulatory footwear.
Fabrication
Obtaining a good fit with an AFO involves one of two approaches: 1. provision of an off-the-shelf or prefabricated AFO matched in size to the end user or 2. custom manufacture of an individualized AFO from a positive model obtaining by means of a negative cast or the use of computer assisted imaging, design, and milling. The plastic used to create a durable AFO must be heated to 400 degrees Fahrenheit, making direct molding of the material on the end user impossible.
There are four major types of AFOs. Flexible AFOs may provide dorsiflexion assistance, but give poor stabilization of the subtalar joint. Anti-Talus AFOs block ankle motion, especially dorsiflexion, but also do not provide good stabilization for the subtalar joint. Rigid AFOs do block ankle movements and stabilize the subtalar joint, and may also help control adduction and abduction of the forefoot. AFOs made with the Tamarack Flexure Joint, however, provide subtalar stabilization while allowing free ankle dorsiflexion and free or restricted plantar flexion, depending upon the design. AFOs made with a special version of this joint may even provide dorsiflexion assistance to correct foot drop.[4]
The International Committee of the Red Cross published their manufacturing guidelines for Ankle-Foot Orthoses in 2006.[4] Their intent is to provide standardized procedures for the manufacture of high-quality modern, durable and economical technology to people with disabilities throughout the world. Please refer to the ICRC manual directly for fabrication details.
References
- ^ a b Michael, JW. Lower limb orthoses, in AAOS Atlas of Orthoses and Assistive Devices, J Hsu, J Michael and J Fisk, eds. 2008, Mosby Elsevier; Philadelphia, PA, p. 343-355.
- ^ Whiteside, S., et al. Practice analysis of certified practitioners in the disciplines of orthotics and prosthetics. 2007, American Board for Certification in Orthotics and Prosthetics, Inc., Alexandria, VA.
- ^ Centers for Medicare and Medicaid Services, PSPS Files 2001-2006.
- ^ a b ICRC AFO Manufacturing Guidelines
External links
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