Sports and Recreation for Those with Lower Limb Amputation or ...
Sports and Recreation for Those with Lower Limb Amputation or ...
Sports and Recreation for Those with Lower Limb Amputation or ...
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this push off is a basic requirement<br />
<strong>f<strong>or</strong></strong> running . In an ef<strong>f<strong>or</strong></strong>t to<br />
simulate push off, the VA SEATTLE<br />
foot <strong>or</strong>iginally inc<strong>or</strong>p<strong>or</strong>ated a series<br />
of leafsprings in the ball of the<br />
foot. When the jogger rolled onto<br />
the ball of the foot, the leafsprings<br />
compressed, st<strong>or</strong>ing kinetic energy<br />
<strong>f<strong>or</strong></strong> release in whatever direction<br />
one desired.<br />
The most current design of the<br />
VA SEATTLE foot replaces the leafsprings<br />
<strong>with</strong> one integral beam, <strong>or</strong><br />
keel, that runs to the ba!l of the<br />
foot. Thofoot ismade outofthermoplastic<br />
material <strong>and</strong> has two<br />
components—the spring assembly<br />
<strong>and</strong> foam . This assembly operates<br />
in the same fashion as the<br />
leafspring foot (by st<strong>or</strong>ing <strong>and</strong> releasing<br />
energy), but it offers m<strong>or</strong>e<br />
simplicity in design.<br />
At this time, the keel design <strong>and</strong><br />
cosmesis have been st<strong>and</strong>ardized.<br />
Alignment of the prosthesis also<br />
is imp<strong>or</strong>tant . Preliminary studies<br />
show that the "running" prosthetic<br />
foot should be set in plantar flexion<br />
so the runner's weight can be<br />
centered over the ba!l of the foot<br />
during push off. Bench testing has<br />
included a th<strong>or</strong>ough <strong>f<strong>or</strong></strong>ce/motion<br />
study of all parameters of per<strong>f<strong>or</strong></strong>mance<br />
together <strong>with</strong> breakage,<br />
fatigue, <strong>and</strong> endurance studies . In<br />
addition to these bench tests cartied<br />
out at the Prosthetics Research<br />
Study <strong>and</strong> in contract facilities,<br />
the foot has been tested at the<br />
Army lab<strong>or</strong>at<strong>or</strong>ies, Natick, Massachusetts.<br />
Gait research continues<br />
in VA facilities <strong>and</strong> in other established<br />
gait lab<strong>or</strong>at<strong>or</strong>ies.<br />
The outst<strong>and</strong>ing acceptance of<br />
this component by users encourages<br />
its broad use in the large<br />
maj<strong>or</strong>ity of adults <strong>with</strong> lower limb<br />
amputation . The above-knee amputee,<br />
Jeff Keith, who completed a<br />
cross-country run from Boston to<br />
Los Angeles in 1884 ' had a VA<br />
SEATTLE foot inc<strong>or</strong>p<strong>or</strong>ated into<br />
his prosthesis.<br />
The VA SEATTLE foot is ready<br />
<strong>f<strong>or</strong></strong> commercialization <strong>and</strong> general<br />
availability. Data gathered from<br />
the 550 individuals <strong>with</strong> amputation<br />
who have been wearing the<br />
foot <strong>f<strong>or</strong></strong> varying periods of time<br />
over the past 3 years are being<br />
compiled by the Evaluation Unit of<br />
the Rehabilitation Research <strong>and</strong><br />
Development Service at the Veterans<br />
Administration Central Office<br />
in Washington, D .C. The Prosthetics<br />
Research Study will continue<br />
to improve <strong>and</strong> refine the concept<br />
that has resulted in the successful<br />
development of the VA SEATTLE<br />
foot.<br />
F<strong>or</strong> m<strong>or</strong>e in<strong>f<strong>or</strong></strong>mation on the VA<br />
SEATTLE foot, contact:<br />
^Drew A. Hittenberger, C9<br />
Chief, Research Prosthetics<br />
Prosthetics Research Study<br />
1102 Columbia<br />
Seattle, WA 98104<br />
(206) 622-7717<br />
Another prosthesis, similar in<br />
concept to the VA SEATTLE foot<br />
but revolutionary in design, is the<br />
Flex-Foot (Fig. 39) . This prosthesis<br />
has a graphite c<strong>or</strong>e which is impervious<br />
to water, humidity, heat,<br />
cold, <strong>or</strong> c<strong>or</strong>rosion . It has no bolts<br />
to rust <strong>or</strong> break, no wood keel, <strong>and</strong><br />
no conventional foam heel to rot<br />
<strong>or</strong> break down. It also has infinite<br />
spring fatigue life, an inherent feature<br />
of the graphite composite<br />
structure. The Flex-Foot's graphite<br />
composite c<strong>or</strong>e, although it has a<br />
higher specific strength than steel,<br />
weighs just 40 percent as much as<br />
a comparable aluminum structure.<br />
At heelstrike, energy is st<strong>or</strong>ed in<br />
preparation <strong>f<strong>or</strong></strong> push-off. At midstance,,<br />
the released high energy<br />
of the propelled drive combined<br />
<strong>with</strong> the inherent flexibility of the<br />
system overcomes the customary<br />
"break" <strong>or</strong> jerkiness . At toe-off, the<br />
flexed leg, <strong>with</strong> the st<strong>or</strong>ed energy<br />
from the <strong>f<strong>or</strong></strong>ward momentum, can<br />
now release <strong>and</strong> spring-assist the<br />
leg to initiate mid-swing action .<br />
36<br />
The cosmetic cover is constructed<br />
of closed-cell, cross-linked,<br />
tear-resistant polyethylene foam.<br />
It is light, waterproof, <strong>and</strong> easily<br />
replaceable.<br />
F<strong>or</strong> m<strong>or</strong>e in<strong>f<strong>or</strong></strong>mation on the<br />
Flex-Foot, contact:<br />
"Flex-Foot, Inc.<br />
19600 Fairchild, Suite 150<br />
Irvine, CA 92715<br />
(714)47S-U650<br />
Another prosthetic foot suitable<br />
<strong>f<strong>or</strong></strong> running is the S.A .F .E . (stationary<br />
attachment flexible endoskelethe<br />
Flex-<br />
Foot . (Photo courtesy of Van Phillips, Flex-<br />
Foot,