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The
myoelectrical hand prosthesis is an
alternative to conventional hook prostheses
for patients with traumatic or congenital
absence of forearm(s) and hand(s). These
prostheses have a stronger pinch force,
better grip, and are more flexible and
easier to use than conventional hooks.
Myoelectrical control is used to operate
electric motor-driven hands, wrist, and
elbows. Surface electrodes embedded in the
prosthesis socket make contact with the skin
and detect and amplify muscle action
potentials from voluntarily contracting
muscle in the residual limb. The amplified
electrical signal turns on an electric motor
to provide a function (e.g., terminal device
operation, wrist rotation, elbow flexion).
The newest electronic control systems
perform multiple functions, and allow for
sequential operation of elbow motion, wrist
rotation and hand motions.
Myoelectrical hand prostheses provide
improved function and range of functional
position as compared to “hook” prostheses.
Myoelectrical hand prostheses can be used
for patients
with congenital limb
deficiencies and for patients with
amputations sustained as a result of trauma
or surgery. The device is appropriate for
both above-the-elbow and below-the-elbow
amputees, and for both unilateral and
bilateral amputees. Patients must possess a
minimum microvolt threshold (i.e., minimum
strength of microvolt signals emitting from
the remaining musculature of the arm) and
pass a control test to be considered a
candidate.
Myoelectrical hand prostheses are indicated
for persons at least one year of age or
older. Children with congenital absence of
the forearm(s) and hand(s) are usually
fitted with a conventional passive
prosthesis until approximately age 12 to 16
months, at which time they may be fitted
with a myoelectrical prosthesis.
Myoelectrical hand prostheses generally come
with a one-year warranty for parts and
labor. The motor and drive mechanisms
typically last 2 to 3 years and may need to
be replaced after this period. When used on
a child, the sockets may need to be replaced
every 12-18 months due to growth. With heavy
use the entire prosthesis might require
replacement by the fifth year. |
