Sports and Recreation for Those with Lower Limb Amputation or ...

this push off is a basic requirement
for running . In an effort to
simulate push off, the VA SEATTLE
foot originally incorporated a series
of leafsprings in the ball of the
foot. When the jogger rolled onto
the ball of the foot, the leafsprings
compressed, storing kinetic energy
for release in whatever direction
one desired.
The most current design of the
VA SEATTLE foot replaces the leafsprings
with one integral beam, or
keel, that runs to the ba!l of the
foot. Thofoot ismade outofthermoplastic
material and has two
components—the spring assembly
and foam . This assembly operates
in the same fashion as the
leafspring foot (by storing and releasing
energy), but it offers more
simplicity in design.
At this time, the keel design and
cosmesis have been standardized.
Alignment of the prosthesis also
is important . Preliminary studies
show that the "running" prosthetic
foot should be set in plantar flexion
so the runner's weight can be
centered over the ba!l of the foot
during push off. Bench testing has
included a thorough force/motion
study of all parameters of performance
together with breakage,
fatigue, and endurance studies . In
addition to these bench tests cartied
out at the Prosthetics Research
Study and in contract facilities,
the foot has been tested at the
Army laboratories, Natick, Massachusetts.
Gait research continues
in VA facilities and in other established
gait laboratories.
The outstanding acceptance of
this component by users encourages
its broad use in the large
majority of adults with lower limb
amputation . The above-knee amputee,
Jeff Keith, who completed a
cross-country run from Boston to
Los Angeles in 1884 ' had a VA
SEATTLE foot incorporated into
his prosthesis.
The VA SEATTLE foot is ready
for commercialization and general
availability. Data gathered from
the 550 individuals with amputation
who have been wearing the
foot for varying periods of time
over the past 3 years are being
compiled by the Evaluation Unit of
the Rehabilitation Research and
Development Service at the Veterans
Administration Central Office
in Washington, D .C. The Prosthetics
Research Study will continue
to improve and refine the concept
that has resulted in the successful
development of the VA SEATTLE
foot.
For more information on the VA
SEATTLE foot, contact:
^Drew A. Hittenberger, C9
Chief, Research Prosthetics
Prosthetics Research Study
1102 Columbia
Seattle, WA 98104
(206) 622-7717
Another prosthesis, similar in
concept to the VA SEATTLE foot
but revolutionary in design, is the
Flex-Foot (Fig. 39) . This prosthesis
has a graphite core which is impervious
to water, humidity, heat,
cold, or corrosion . It has no bolts
to rust or break, no wood keel, and
no conventional foam heel to rot
or break down. It also has infinite
spring fatigue life, an inherent feature
of the graphite composite
structure. The Flex-Foot's graphite
composite core, although it has a
higher specific strength than steel,
weighs just 40 percent as much as
a comparable aluminum structure.
At heelstrike, energy is stored in
preparation for push-off. At midstance,,
the released high energy
of the propelled drive combined
with the inherent flexibility of the
system overcomes the customary
"break" or jerkiness . At toe-off, the
flexed leg, with the stored energy
from the forward momentum, can
now release and spring-assist the
leg to initiate mid-swing action .
36
The cosmetic cover is constructed
of closed-cell, cross-linked,
tear-resistant polyethylene foam.
It is light, waterproof, and easily
replaceable.
For more information on the
Flex-Foot, contact:
"Flex-Foot, Inc.
19600 Fairchild, Suite 150
Irvine, CA 92715
(714)47S-U650
Another prosthetic foot suitable
for running is the S.A .F .E . (stationary
attachment flexible endoskelethe
Flex-
Foot . (Photo courtesy of Van Phillips, Flex-
Foot,