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CHAPTER 30
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The Child with a Limb Deficiency
Heel
cushion
Keel
Foam rubber
Belting
A
B
C
Graphite strut
Polyurethane foam
D
FIGURE 30-52.
A
: In the conventional style SACH foot, the length of the keel controls the toe lever arm, and therefore the
hyperextension moment at the knee, while the compression of the material at the heel absorbs the forces at heel strike.
B
: The
Little Feet type design incorporates unique energy dynamics with flexible toes all in sizes beginning at 10-cm length. The length
of the keel controls the toe lever arm and thus the hyperextension moment at the knee, and the compression of the elastomer
heel absorbs and deflects the forces at heel strike.
C
: The dynamic multiaxial TruPer foot allows rotation, inversion and ever-
sion, flexion, and extension movements. The outer cosmetic shell can be exchanged for larger shells as the child grows.
D
: The
Flex-foot is a dynamic-response foot with much different performance characteristics than the SACH foot or multiaxial foot. It
is used for the older, stronger, and physically active child who has the physical ability to use such a foot.
At slower walking velocities, there is little difference
between the dynamic-response foot and the SACH foot (229).
Generally, children are not fitted with the highest-performance
dynamic-response feet, because of constant growth and weight
changes and the high costs associated with foot replacement.
The involvement in competitive sports is usually a good
benchmark to initiate fitting adolescents with the highest-
performance dynamic-response feet.
In the transfemoral amputee, it is crucial to properly
choose a foot that will enhance gait, but also to choose the
complementary knee that will aid in controlling the foot
during all aspects of the gait cycle. A common mistake is to
prescribe a dynamic-response foot with a simple, friction-
controlled knee that is incapable of preventing uncontrolled
heel rise. The same is true of the transtibial amputee, who
lacks the muscle strength to control the foot, often resulting
in premature muscle fatigue. In the selection of multiple com-
ponents, the prosthetist must marry the characteristics of all
components, so that maximum benefit can be available to the
amputee.
