Case Study Demonstrates Innovative Silicone Technique for Bilateral Wrist Disarticulation

PARK CITY, Utah — Benjamin J. Koch, BS, CP,
Orthotic Prosthetic Center Inc, shared a case study about a boy he is currently
working with who, at 18 months old, was diagnosed with septic shock, which
resulted in bilateral wrist disarticulation as well as bilateral
transtibial amputation in addition to renal failure. Koch
first met the boy when he was 3 years old and outgrew his first set of legs.
Koch fit the boy with his second set of legs and his first set of arms. At 3
½ years old, the boy needed a third set of legs. It was at this time
Koch also began to design silicone sockets for his next set of upper extremity

“When we first fit his definitive sockets for his
first round of upper extremity prostheses, he was extremely happy and motivated
to use them,” Koch explained to the audience at the
2011 Association of Children’s Prosthetics-Orthotics Clinics
Annual Meeting
. “He quickly adapted to manipulate the left side which
we fit with the body-powered closing hand and the right side was a passive

For the first 2 weeks, the boy was excited to use them
in physical therapy. But soon he became more self-aware. His mom called Koch
and said that he referred to his prostheses as “ugly.”

“This was heartbreaking but on the flip side it was
motivating to find something that wouldn’t have that reaction,” Koch
said here. “It was my motivation to create something he would

Koch found a 2007 survey that suggested among pediatrics
there was a rejection rate of 45% for upper extremity body powered prosthetics
and 35% electric prostheses. Koch wanted to eliminate all of the rejection
variables he could control so he decided to use a myoelectric prosthesis to
give the boy more functionality.

“The prosthetic solution was to integrate these
myoelectric components for his new prostheses and to integrate them into a full
silicone socket,” Koch said. “The beauty of the silicone is that we
could kind of make it a little more rigid in the places we needed it and
flexible enough at the elbow so when he has range of motion, it would be
dynamic and flowing.”

One of the biggest questions for Koch was how does he
integrate all of the myoelectric components such as the wires, battery and the
electrodes within the silicone socket while remaining natural looking for the

Koch built up the prostheses with the components through
numerous fittings. When he added in the battery units during the second
fitting, he found it was too bulky. On the next set of sockets, during the
buildups and the modifications, he ran the battery unit medially. The
definitive socket was color matched to the boy’s skin and also hid the
componentry within the silicone socket while remaining accessible for Koch.

“We needed to be able to get at that wrist unit in
case the wires came apart or we lost connection, which did happen at one
point,” he explained.

As the boy grows, he will need to be fit with new
prostheses. Koch started this process in August and he has not completely fit
the boy in a definitive socket. This is due to the boy’s other health
complications that have taken priority over fitting appointments.

“I also hope that as he grows, we can reuse the components that
were integrated to the silicone if we needed to move forward with another
set,” Koch said. — by Anthony Calabro


This article raises a couple of important issues for
fitting upper limb amputees. The literature suggests that there is a
significant rejection rate for upper limb prostheses. Critical factors that may
lead to rejection are related to comfort, function and appearance. Finding new
ways to fit upper limb amputees with designs that improve upon what was
previously available is necessary to address the rejection rate. Custom
silicone construction offers advantages that address each of the three areas
that are cited by users for dissatisfaction.

Use of custom silicone is proving to be advantageous for
upper limb prostheses of all levels due to the many ways it can be customized
including variable stiffness, ability to integrate electronics and other
componentry, custom coloring and the durability of high consistency rubber

— Jack Uellendahl, CPO
Upper limb
specialist, Hanger Orthotics and Prosthetics Inc.

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