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VASI Offers Advanced Pediatric Hand Technology
By William J. Hanson, MS
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Figure 1 |
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The latest development in pediatric hand
technology is the new Single Program-ming Module (SPM") circuit
from Variety Ability Systems, Inc. (VASI) [Figure 1]. The SPM
offers many features not previously available in prosthetic hand
controllers. The circuit uses surface-mount technology, thus
enabling VASI to make it lightweight and compact enough to fit all
children's hand sizes from ages 1-11.
The microprocessor-based SPM circuit dramatically increases
versatility and allows the use of a computer to set up and adjust
the prosthetic system--an advanced feature that separates this
controller from much of the competition.
The hand control strategy is downloaded from the VASI MyoWizard"
system software [Figure 2]. This software has a patient evaluation
mode that enables the prosthetist to look at muscle signal strength
and adjust the prosthetic system to match the user's capabilities.
VASI's proprietary interface software, MyoAssistant", displays
simple bar graphs or time-history charts of muscle signal
strength.
With the computer display, not only the prosthetist, but also
the child and the parents can actually "see" the signals that are
controlling the prosthetic system. Since many children are visual
learners, this approach helps them understand what their various
actions do--a concept that is often difficult for children to
grasp.
Eight Control Strategies Available
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Figure 2 |
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At present, there are eight control strategies to
choose from, based on the number of sites (one or two), the type of
input device preferred (myoelectrodes, Touch Pads" or switches),
and the output device (hand type). There are also many other
control options which help the prosthetist match the control scheme
to the patient's capabilities. Once properly set up, the system
will be relatively easy for the child to operate because it has
been "tuned" specifically for him/her. If the child needs a wrist
rotator in addition to the electric hand, an LTI VariGrip" in-wrist
controller can be used in lieu of the SPM hand circuit. This
controller uses the same software, making it easy for practitioners
to switch back and forth between them.
System Stores Information
The SPM and VariGrip prosthetic controllers have another
interesting feature. They can store information about the
prosthetic system's use, so the practitioner can review the
information while servicing the prosthesis. The ability to reliably
determine how frequently the prosthetic system is used and how it
is being operated can be very helpful when dealing with children
who cannot express themselves adequately. Usage information is also
valuable when justifying the need for a new prosthesis. No longer
must payers rely on "timeframe" when determining the need for
replacement. Instead they can use the actual measured usage
data.
For more information, 508.893.6363; www.liberatingtech.com. William J. Hanson is president of Liberating Technologies Inc., Holliston, Massachusetts. 
Table Of Contents - October 2003
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