Static orthoses serve to protect, immobilize, and help prevent or correct contractures.
* The proximal interphalangeal (PIP) orthosis is used to immobilize the PIP joint hyperflexion deformities in patients with Boutonniere deformities or to prevent hyperextension of the PIP joint in swan-neck deformities, both of which are found in patients with rheumatoid arthritis.
* The distal interphalangeal (DIP) orthosis is used to immobilize the DIP joints in extensor tendon and collateral ligament repairs.
* The MP orthosis is used to maintain a functional position for the distal phalanges, while preventing hyperextension of the MP joints. These devices are used in patients with burns, scleroderma, or nerve injuries.
* The static thumb orthosis is used to support the carpometacarpal joint, the interphalangeal joint, or the metacarpophalangeal joint in patients with traumatic or arthritic conditions, and in patients with thenar muscle weakness by providing static support for the thumb.
Dynamic hand orthoses are used to maintain support, while at the same time to provide dynamic corrective force in positioning the fingers, assisting weak motor finger extensor function. These devices are used with outrigger supports, cuffs, elastic threads, rubber bands, and hook applications for their function of providing dynamic assistance.
* The MP joint dynamic orthosis is used to assist with flexion of the DIP joint in swan-neck deformities and to act as a substitute for weakness of the flexor digitorum superficialis muscle. The MP joint dynamic orthosis also can be used in correcting or maintaining contractures of the MP joints.
* A dynamic PIP joint extension with MP extension stop device is comprised of a bar placed across the dorsum of the hand and is used in patients with ulnar nerve palsy with claw hand deformity by allowing extension while resisting flexor deformity pull.
* A thumb interphalangeal dynamic orthosis is used to assist in interphalangeal joint extension of the thumb, while maintaining the position of the other hand joints. This device is used to substitute for weakness of the extensor pollicis longus muscle.
* A reciprocal wrist-extension finger-flexion orthosis is used in patients with C6 tetraplegia who, given their level of injury, can extend their wrists but cannot flex their fingers. By using the wrist extension force, finger flexion at the MP joints of the second and third digits is attained. Wrist extension is used to flex the MP joints of digits 2 and 3 through tenodesis. Preservation of extensor carpi radialis longus and brevis normally is observed in C6 level SCI. Use of this device allows for a 3-point pinch.
* The MP extension splint has the same mechanism as the MP flexion splint; however, it is placed on the dorsal side and serves mainly as a splint in patients with weak wrist extensors and for traction of MP flexion contractures.
Upper Extremity Orthoses With Special Functions
Tenodesis orthoses are used to facilitate 3-jaw chuck prehension use of the natural tenodesis action of the wrist. This action requires that the wrist extensor motor strength be at least a 3+/5 (on a 0-5 muscle grade scale). When the wrist extends, the thumb is pulled in opposition with the second and third digits, movement that is particularly useful in patients with C6 level tetraplegia who can manage radially deviated wrist extension.
Examples of tenodesis splints include the following:
* The wrist driven flexor hinge splint has a design that includes a MP spring-activated ratchet lock that functions to sustain the pinch after the wrist relaxes.
* The Rehabilitation Institute of Chicago orthosis is comprised of 3 separate pieces that include a short opponens, an index and middle finger dorsal plate, and wristlet.
* The externally powered tenodesis orthosis uses myoelectric or switch control and/or an electric motor to power the device.
Tone reduction orthoses
* These devices are used for flexor tone reduction in patients with significant spasticity, as is observed commonly in cerebrovascular accidents, MS, TBI, and CP.
* The more common tone reduction orthoses include the Bobath splint, cone splint, and antispasticity ball splint.
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