Adjusting to a
prosthetic leg
and foot
Chandler’s doctor, Phoebe Scott-Wyard, a
pediatric physiatrist (physical medicine and
rehabilitation physician treating children and
young adults), notes that walking and running
with his prosthetic leg has been challenging
for Chandler. He was accustomed
to using a prosthetic leg with a
knee joint for everyday use (sim-
ilar to the one shown in Fig. 1b),
but the new prosthetic leg (similar
to the one shown in Fig. 1a) did not
have a knee—so Chandler had to learn how
to move with a prosthetic leg made without a
knee. When he was running, he had to learn
how to move his leg so his foot traces a circle,
while the top of his leg remains fixed.
The other major challenge is financial. Prosthetic legs are often cost-prohibitive, with an
average cost of $5,000–$15,000—but until
he was 18 years of age, Chandler received
a prosthetic leg and prosthetic running foot
every year, along with all care and services,
which are provided at Shriners regardless of a
patient’s family’s ability to pay. Shriners could
no longer offer Chandler free prosthetics
and related services once he turned 18. As a
result, Chandler’s parents initiated a crowdfunding Web site to help raise the funds for
new prosthetics. A crowdfunding site raises
small amounts of money from many people,
primarily via an Internet campaign.
When Chandler received his
new prosthetic leg, he was
concerned there might be
problems with the way it fits,
because the remainder of his
right leg—called a stump or
residual limb—might respond to
the prosthetic in ways that may
affect how it fits. He engaged
in regular training at his physical therapist’s office—which
involved work on parallel bars,
stairs, ramps, and level ground.
The prosthetic leg’s fit was
fine-tuned by making small adjustments in
the region where the leg contacts the residual
limb, helping Chandler to learn how to accom-
modate his new leg. Now, Chandler says, he is
excited about his most recent prosthetic leg,
which fit well, adding, “I never felt so comfort-
able running in my life.”
In fact, Chandler’s new pros-
thetic leg and foot are working
so well that he would like to
become a personal trainer,
own a gym, and compete in
triathlons and Spartan races.
“My new prosthetics enable me
to run better at longer distances
without pain,” he says.
Prosthetic leg
To make sure the prosthetic
leg lasts at least 6 months, it
needs to fit the shape of the
leg comfortably, not irritate the
skin, and be sturdy enough to
be worn all day in a rigid socket
and washed every night. Pros-
thetic designer Denis Jordan,
who works for Shriners Hos-
pitals, addressed these issues
with an innovative socket design
and silicone liner. The liner,
Silicone elastomers are made of long mole-
cules, each consisting of repeating units com-
posed of one silicon atom, two carbon atoms,
and one oxygen atom (Fig. 2). Each molecule
consists of a backbone of alternating silicon
and oxygen atoms, and the remaining two
bonds of the silicon atoms occur with organic
groups, such as methyl groups (–CH3).
The prosthetic leg needs to be compatible
with living tissue, or biocompatible—that is,
it should not release chemicals that are toxic
to the body. The material of choice to prevent
this from happening is titanium, a lustrous sil-ver-colored transition metal with high strength
and high resistance to corrosion in seawater.
More important, titanium’s surface properties
with his prosthetic leg has been challenging
e
si
-
t
lr
f
n
t
o
r
o
Figure 2. Chemical structure of a silicone elastomer
H3C Si
CH3
CH3
O Si
CH3
CH3
O Si
CH3
CH3
O
Repeating
unit
Si
CH3
CH3
O Si
CH3
CH3
O Si
CH3
CH3
CH3 . . .
{
“I never
felt so
comfortable
Chandler Smith
Residual Limb
Socket
Rotator
Knee Joint
Pylon
Pylon
(distributes weight from the
socket to the foot)
Prosthetic Foot Shell Prosthetic Foot Shell
Prosthetic Foot
Residual Limb (b)
Socket
(shock-absorbing)
Gel Liner
(custom-made to fit the
amputee and distribute weight) Gel Liner
Prosthetic Foot
(a)
Figure 1. Prosthetic legs come with or without a knee. (a) In a prosthetic leg without a knee, the pylon
(lower part of the prosthetic) and the socket (which replaces the lower part of the thigh) are directly
attached to each other. (b) In a prosthetic leg with a knee, a knee joint and a rotator are present between
the pylon and the socket, allowing the prosthetic leg to bend.
