Appropriate Fit: The Key for Successful Use of Prefabricated Upper Extremity Orthotic Devices
Lynn Thibault Toni Thompson
The goals of upper extremity orthotic devices, custom- made or pre-fabricated, include enhancing function, improving position, and preventing deformities for the child and adolescent with cerebral palsy, arthrogryposis, or other neurological, orthopaedic, or congenital condition.
Pre-fabricated orthotic devices, from a variety of manufacturers, can provide appropriate positioning for the wrist, hand, fingers, and thumb to enhance function. The pre-fabricated devices often do not offer appropriate fit in their basic off-the-shelf form.
Several keys points with attention to the bony prominences and anatomical landmarks must be incorporated to effectively fit the orthotics devices. Adaptations can help to insure appropriate fit.
KEY: FIT EACH SPLINT TO EACH CHILD!
WRIST IMMOBILIZATION SPLINT
GOAL: ENHANCE FUNCTIONAL USE OF THE HAND
Keys to appropriate fit:
- Adequate length. The splint should cover 2/3 the length of the forearm to allow for adequate distribution of pressure.
- NOT TOO SHORT. A short forearm component can increase the amount of pressure. If the force on the forearm is not distributed well enough to counterbalance the resistance of tone of the wrist flexors, the splint may not provide adequate support and result in a deforming position of the wrist. (Hogan, p. 15-16) (Jacobs and Austin, p. 59-62.)
- NOT TOO LONG. A forearm component that is too long may result in the inability to flex the elbow and potentially cause red marks and bruising on the elbow or upper arm.
- Adequate digit function. For adequate movement and function of the metacarpals (MPs), the Distal Palmar Crease should be free. (Coppard, p. 51-52) (Hogan, p. 10) (Jacobs, p.30-31).
- The extended distal aspect of the splint blocks the MP into full extension, and allows interphangeal joints (IPs) to flex, causing a deforming position of the digits.
- Adequate wrist position. Adequate wrist support helps to maintain wrist in neutral in terms of radial and ulnar deviation.
- A loose forearm trough allows the wrist to migrate into ulnar deviation, a potentially deforming wrist position.
- A trough that is too wide does not provide adequate wrist support, allowing ulnar deviation.
- Adequate wrist-digit position. The degree of wrist extension necessary for function can vary from the actual available ROM of the wrist. The digits must be functional, and sometimes this involves maintaining the wrist in neutral or slight flexion rather than maximum available wrist extension.
- When the digits are flexed and unable to extend, a good solution is modify the splint to include increased wrist flexion.
WRIST HAND IMMOBILIZATION ORTHOSIS
GOALS: ENHANCE POSITION FOR FUTURE FUNCTION PREVENT OR DECREASE WRIST AND HAND CONTRACTURES
Keys to appropriate fit:
- Adequate length. Correct proximal and distal length provides adequate support and distributes pressure by incorporating contact with sufficient body surface (Jacobs 59-62).
- A fulcrum that is too short can cause discomfort and fail to adequate maintain the wrist in optimal position. (Jacobs, p. 61)
- A long fulcrum can interfere with joint motion and movement.
- Adequate width. Snug wrist fit supports a neutral position in terms of ulnar and radial deviation.
- Loose wrist fit and loose straps contribute to an ulnar deviated position.
- Adequate digit position. A balance between wrist extension with some digit flexion is optimal
- When IPs are hyperextended, a better choice to decrease the amount of wrist flexion and allow more MP and IP flexion.
THUMB RESTRICTION SPLINT
GOALS: INHIBIT PALMAR GRASP ENHANCE FUNCTIONAL POSITION AND USE OF THUMB
Keys to appropriate fit:
- Adequate thumb component length. In many cases, the thumb component can be trimmed down to allow for IP movement.
- The standard thumb component may be too long and inhibit functional use of the thumb.
- Adequate web space fit. Assure that the glove is fitted and pulled down snugly into the web space.
- Poor fit into the web space does not adequately support the web space,
- leading to hyperextension of the thumb MP with decreased functional use.
- Adequate function. Manipulation of objects using various types of grasp and pinch are good tests for a functional splint.
Conclusion: Most splints cannot address both functional movement and immobilization for positioning. In the team approach to pediatric orthopaedics, the responsibility of the orthotist is to:
- Work with the team to Determine the goal of the splint, and
- Choose each splint for the of the child to meet the pre-determined goals
Prefabricated splints require attention to the specific details and individualized adjustments to meet each child's anatomy and functional needs.
MA, OTR/L, BCP
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