Orthosis: Supporting Body Function with External Devices
Orthosis is a device externally applied to support or improve body function. The design can immobilize, restrict movement, control, assist, or reduce weight-bearing forces. Prescription considerations include indications, anatomy, deficits, materials, and patient training. Discontinuation factors and immediate adjustments are crucial. The orthotic design should be simple, strong, and comfortable, with material choice based on clinical purpose and patient characteristics.
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Presentation Transcript
By : Abdullah Radwan
Orthosis: a device that is externally applied to the body segment to support or improve the function of that segment.
Depending on the design, an orthosis may: 1. Totally immobilize a joint or body segment, 2. Restrict movement in a given direction, 3. Control mobility, 4. Assist with movement, or 5. Reduce weight-bearing forces. The primary principle behind the prescription of an orthosis is the improvement of function.
PRESCRIPTION CONSIDERATIONS Before prescribing an orthosis, the physician needs to know: The indications for prescribing a specific orthosis, The anatomy and neuromuscular function of the specific body regions, The functional and biomechanical deficits present, The mechanical principles of orthotic application, The materials used in fabrication, The various orthotic designs that are available, and The patient training before and after receiving the orthosis. The orthotic cost versus patient benefits of orthosis. 1. 2. 3. 4. 5. 6. 7. 8.
Discontinuation of the orthotic use should be when: 1. causes pain, 2. reduces function, 3. worsens posture or gait, 4. causes emotional distress, 5. more effective results can be achieved by physical therapy or minor surgical procedures.
Immediate alteration or adjustment of the orthosis occurs in the following: 1. Allergy to the orthotic materials, 2. Restriction of peripheral circulation, or 3. Development of pressure sores.
The orthotic design should be: 1. Simple, 2. Comfortable, 3. Strong, 4. Durable, 5. Adjustable, 6. Functional adding, and 7. As cosmetic as possible.
The choice of the orthotic material depends on : 1. the clinical purpose 2. the characteristics of the patient.
I. Foot Orthoses (FOs): They are removable foot supports made of variable materials placed inside the shoe to manage different foot symptoms and deformities. They have the advantage over shoe modifications in that they can be transferred from shoe to shoe, may be modified without disturbing the shoe, and are more durable than the modified shoe. Indications of FOs: 1. Relief of pressure on areas that are painful, ulcerated, scarred, or calloused, 2. Support weak or flat longitudinal or transverse foot arches, and 3. Control foot position and thus affect the alignment of the lower limb joints.
Types of FOs: Soft or flexible FOs: Used for simple problems, but not in severe conditions. Fabricated in full length from heel to toe with increased thickness where weight bearing is indicated and relief where no or little pressure should occur. Commonly used for ischemic, insensitive, ulcerated, or arthritic feet. The semi-rigid and rigid FOs: Commonly made of solid plastics, which allow minimal flexibility. Generally extend from the posterior end of the heel to the metatarsal heads (i.e., three-quarter length) and may have medial and lateral flanges. Most rigid FOs are made of metal, usually steel covered with leather.
II. Ankle-Foot Orthoses(AFOs): Indications of AFOs: Muscle weakness affecting the ankle and subtalar joints, including weakness of dorsal and plantar flexors, invertors, and evertors. Prevention or correction of deformities of the foot and ankle Reduction of weight-bearing forces. 1. 2. 3.
Types of AFOs: (1) plastic AFOs: More common. Fabricated from either thermoplastic or thermosetting materials, depending on the required function. Inexpensive. Worn inside the shoe and consist of the footplate, an upright component, and a Velcro calf strap. The upright components often extend from the footplate without a joint mechanism to the upper calf approximately 1 to 2 inches below the head of the fibula. (a)A plastic leaf-spring orthosis (PLSO): The most commonly prescribed AFO. It substitutes for weakness of ankle dorsiflexorsand provides some mediolateral stability. (b) A solid-ankle plastic AFO: Used in severe spasticity of the ankle. (c) A plastic spiral AFO: - Used for concomitant weakness of both the ankle dorsiflexors and plantarflexors when spasticity is absent.
(2) Metal AFOs: Have medial and lateral uprights with an ankle joint mechanism. The Klenzak ankle joint orthosis: T-straps may be attached to the shoe medially or laterally to control valgus (i.e., eversion) or varus (i.e., inversion) . Such AFOs are frequently prescribed for neurologic conditions when there is a risk of Achilles tendon shortening. They are usually worn at night only and are not designed for weight bearing.
III. Standard Knee-Ankle-Foot Orthoses Below the knee, the components of the standard knee-ankle-foot orthoses (KAFOs) are the same as those of metal or plastic AFOs, except that the uprights extend to the knee joint, where they join the thigh uprights. A free knee joint is indicated when mediolateral instability or genu recurvatum is present but knee extension strength is adequate for weight bearing. If knee extensors are weak, and buckling occurs, a knee lock or offset joint is indicated. The drop-ring lock is used most commonly. It is placed on the lateral upright bar and drops over the joint when it is fully extended. A cam lock with a spring-loaded cam that fits into a groove in full extension is easier to release but still gives good stability and may be used in severe spasticity. A bail lock (i.e., Swiss lock) is locked position on full extension and unlocks automatically when pressed upward against an object such as a chair. The thigh uprights are connected by a rigid, padded upper thigh band with an anterior soft closure. This band should be 1.5 inches below the ischium, unless ischial rest is prescribed.
The Scott-Craig orthosis: It consists of two uprights with four rigid connections: posterior rigid upper thigh band, bail-type knee lock, rigid anterior upper tibial band with soft posterior strap, and at the lower end, a stirrup with a rigid sole plate built into the shoe extending to the metatarsal heads. It is connected to the uprights by double-stop (Becker) ankle joints that are adjusted to place the orthosis in 5 of dorsiflexion for optimum balance. It is a stable orthosis that biomechanically functions as the standard KAFO.
Modified Knee-Ankle-Foot Orthoses Plastic laminated knee-ankle-foot orthoses KAFOs may include standard ankle and knee components, but the uprights and bands are made of lightweight skin-colored laminated plastic that closely fits the limb. The thigh piece is a quadrilaterally shaped. A suprapatellaror pretibial shell provides knee extension force, which eliminates the need for patellar strap and provides mediolateral knee stability. At the lower end, the uprights are connected to a molded plastic footplate to be worn inside a shoe. Indicated for patients who lack knee and ankle muscle power but have normal hip extensors, full knee extension, and no spasticity.
IV. Knee Orthoses(KOs): KOs are prescribed to prevent genu recurvatum and to provide mediolateral stability. They may be used during sports and other physical activities to provide functional support for unstable knees or during the rehabilitation phase following injury or surgery on the knee. Most KOs consist of two uprights, free or adjustable knee joints, and thigh and calf cuffs. The Swedish knee cage prevents recurvatum but permits flexion. The three-way knee stabilizer orthosis control structural knee instability in the lateral, medial, and posterior directions and is indicated for genu valgum, varus, and recurvatum.
V. Hip-Knee-Ankle-Foot Orthoses (HKAFOs): HKAFOs consist of the same components as described for the standard AFOs and KAFOs, with the addition of an attached lockable hip joint and a pelvic band to control movements at the anatomic hip joint. The Louisiana State University reciprocating gait orthosis : Using two crutches, persons with paraplegia are able to ambulate with a four-point gait pattern.
