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The State of the Art in Upper-Limb Prosthetics: Reflections from Respected Voices
By Judith Otto Our panel of experts:
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Randall Alley, BSc, CP, FAAOP |
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Randall Alley, BSc, CP, FAAOP, is
the head of Clinical Research and Business Development for the
Hanger Prosthetics & Orthotics Upper Extremity Prosthetic
Program. He is chair of the Upper-Limb Prosthetics Society of the
American Academy of Orthotists and Prosthetists (AAOP) and an
international lecturer and consultant.
John M. Miguelez, CP, FAAOP , president of
Advanced Arm Dynamics, Rolling Hills Estates, California, serves as
a clinical consultant worldwide on issues regarding upper-extremity
prosthetics.
John Billock, CPO/L, FAAOP , is a past
president of the American Academy of Orthotists and Prosthetists
(AAOP). He is the clinical/executive director of the Orthotics
& Prosthetics Rehabilitation Engineering Centre, Warren,
Ohio.
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John Billock, CPO/L, FAAOP |
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Diane Atkins, OTR , a clinical
assistant professor in Physical Medicine and Rehabilitation at the
Baylor College of Medicine in Houston, Texas. Atkins is an
occupational therapist who has specialized in amputee
rehabilitation for more than 25 yearswith special focus on
rehabilitation of the upper-limb amputee.
Carl Brenner, CPO , is the director of
Prosthetic Research at the Michigan Institute for Electronic Limb
Development, Livonia, Michigan.
Robert H. Meier III, MD , is the founder of
Amputee Services of America, a comprehensive center of excellence
that addresses issues related to limb amputation. Meiers experience
in rehabilitating persons with amputation encompasses some 2,700
amputees, 45 percent of whom are upper-limb amputees.
Question One
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John M. Miguelez, CP, FAAOP |
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What are some of the most significant
recent advances in upper-limb prosthetic
technology?
Alley: In the component sector, Otto Bock's
sensor hand, Motion Control's flexion wrist for its electric
prehensor, LTI's Boston Elbow 3, and Animated Prosthetic's
PDA-based wireless controller and battery technology have all
contributed greatly to both patient and practitioner
capabilities.
Atkins: Microprocessors that allow a
prosthetist to modify a variety of control options without changing
componentsas was necessary in the pastare a huge advantage. An
experienced prosthetist can do this "troubleshooting" in an initial
fitting; an experienced OT [occupational therapist] can learn to
change the control thresholds as the amputee's strength increases;
and in certain cases, the user can be taught to make these
adjustments himself as he progresses. The transcarpal myoelectric
hand is also a terrific advance.
Billock: The lithium-polymer battery
technology just introduced into prostheses is very impressive.
These smaller batteries are 80 percent lighter than nickel-cadmium
batteries, 70 percent smaller, and offer 30 percent more storage
capacity.
We've been after these batteries for two years, but if you can't
buy them in extremely large quantities, they're unavailableand,
unfortunately, the needs of the prosthetic field are relatively
small. We were only able to get them by appealing to the
humanitarian instincts of their suppliers and manufacturers, with
regard to a young patient in their own backyard. [This humanitarian
response also made] them available for others. The child was born
with complete hand absences just below the wrist. She was fitted
with two myoelectric hands, but routinely ran them out of power
within four to five hourscouldn't get through a day of active
exploration and learning.
 The new lithium-polymer batteries hadn't really
been applied to prosthetics before, and we had to meet special
requirements in the circuit design of the prosthesis to satisfy the
manufacturer of the batteries. These are the batteries that for 25
years I've been waiting for.
There are also improvements in motor technology that we're aware
of, but which still haven't been introduced into some of the
systems that are out there. They offer enhanced durability, speed,
and torque.
There's a lot going onenhanced control systems are becoming
available. We've developed our own electronic control system for a
myoelectric prosthesis, which is the smallest available today;
others are also making similar advances.
Brenner: I find that our patients are
delighted with the new batteries that are available. There have
been a lot of advances, but for patients that have been wearing
externally powered prostheses, the lithium-ion power systems that
are available now are very fast, easy to charge, a little lighter
in weight, and have much greater capacity than nickel-cadmium power
systems.
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Hanger Upper Extremity Prosthetic Specialist Steve Mandacina, CP, helps five year old Ethan Wright don his new myoelectric prosthesis. Photos courtesy of Hanger Prosthetics & Orthotics |
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Another welcome advance is the availability of
programmable microprocessor circuits, which allow the prosthetist
to truly customize and fine-tune the control strategies for each
patient.
Also, new components, such as the transcarpal hand, allow us to
fit longer forearm lengths than ever before and come up with a more
cosmetic result.
Improved silicone suction suspension systems have been very
helpful, as have lighter and cooler socket designs that provide
more patient comfort and better cosmesis.
Miguelez: I think there are two different
aspects to consider here:
1) the evolution of third-generation electronics, including the
wider use of microprocessors and all their benefits. We've just
submitted a paper to JPO [Journal of Prosthetics and Orthotics] on
that subjecta comparative analysis of microprocessor controllers.
There's just so much more we can do now with using an electrically
powered terminal device or elbow, and how we can control that by
the types of inputs, and by the way we refine the EMG signal and
how it's filtered. All of that really wasn't available several
years ago, so that's very exciting to us. That's one phase.
2) There have also been some neat advancements in terms of
body-powered designs: The ERGO Arm elbow system is a very exciting
elbow for the body-powered user because of its lock. It allows a
counter-balance system that makes it easier for amputees to flex
the elbow. They don't have to work against the weight of the
forearm. The locking device in the elbow is also much more advanced
and allows more efficient control.
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Photo courtesy of Motion Control, Inc. |
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Another significant advance is in interface
design. The introduction of the MicroFrame, which is the shoulder
disarticulation four-quarter humeral-neck type of socket design
that does not encapsulate the shoulder, has now allowed us to fit a
lot of patients that, until a few years ago, were not considered
prosthetic candidates. That's exciting.
For several years now, we've been using the Anatomical Contoured
Interface, which is an interface for either the transradial,
styloid, or transhumeral level that really grasps the skeletal
anatomy and creates pockets or areas for expansion for the muscles.
This is important because we want to promote hypertrophy or muscle
growth in an interface, as opposed to an interface that creates
atrophy or muscle shrinkage.
This provides more stability, comfort, and suspension for
patients. The more comfortable it is, the longer patients will wear
it and the more things they will do with it, increasing their
overall functionality.
Meier: The most significant technology I have
seen is the electric locking shoulder joint, closely followed by
proportional controls for electric technology and the increasing
use of the silicon cosmetic glove within the last ten years.
Question Two:
What are some of the most significant recent
advances in clinical practice?
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Photo courtesy of Liberating Technologies Inc. |
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Alley: I feel that interface
designs have significantly improved in the last decade. The
anatomically contoured and controlled interface (ACCI) for
radioulnar or below-elbow level, the dynamic socket for humeral or
above-elbow level, and the XFrame for thoracic applications have
all had a tremendous impact on prosthesis comfort, stability,
suspension, and overall function, which in turn have had a
favorable impact on patient acceptance of the prosthesis. I also
believe the utilization of the expedited fitting procedure that was
originally developed within NovaCare's Upper Extremity Prosthetic
Program and has been adopted by Hanger Prosthetics & Orthotics
Inc. as well as others, is an extremely significant advance in
clinical practice. I feel that the push for justifying multiple
prostheses and the increase in trial fittings are tremendously
beneficial for upper-extremity patients.
Atkins: I'm seeing a more acute awareness and
effort on the part of prosthetists to work closely with an OTand
vice versain order to optimally fit and train the upper-limb
amputee. There is still a significant distance to go to develop an
effective network and "bridge" of communication with each other,
but educational efforts are underway and the AOTA [American
Occupational Therapy Association] is strongly behind these
initiatives. Also, a conference to better address the need,
functional issues, and challenges of the bilateral UE amputee was
held in Denver in September 2002. It was taught by prosthetists,
therapists, a physician, and also by bilateral UE amputees
themselvesand it was a huge success. Only 10-15 amputees were
expected, but 25 attended and participated, in addition to 25
professionalsplus exhibi-tors, spouses, etc.
Billock: Clinically there has been little
progress from my viewpoint. There are some clinical procedures that
aren't being applied&that folks could pay closer attention
to.
For example, all the myoelectric control systems that are being
developed today have higher gain sensitivity, so that if someone
has weak muscles, they can control the system. It has taken the
focus away from the pre-prosthetic training that needs to go on to
improve the physiological condition of the muscles and that
person's proprioceptive control of the muscles. There has never
been enough focus on that particular aspect, from my point of view,
and now there is less. Prosthetists are relying too much on the
electronic system itself to pick up the signal from a muscle that
is weak, rather than focusing on pre-prosthetic muscle
development.
Additionally, there is difficulty in finding a trained therapist
who understands upper-limb prosthetics and the rehabilitation needs
of someone with an upper-limb prosthesis. When I work with
therapists, I often find that they ask me what they should be doing
with the patientessentially, I'm training the therapist. Like
everything else, this takes time? reimbursement becomes an issue
when I spend too much of my time in unbillable pursuits, even
though it is a necessity.
Brenner: We're seeing more focus now on the
need for early intervention. With upper-limb prosthetics, there has
historically been up to a 50 percent rejection rate prior to the
1980s. Within the last decade, however, we've seen more focus on
early fittingswithin just a week or at most 30 days from the date
of amputation. That has improved outcome measures significantly in
terms of patient utilization of the prosthesis as incorporated into
their daily wear and use patterns.
The development of specialty teams and the whole concept of
expedited fittings has also improved care. About 90-95 percent of
our practice is upper-limb prosthetics, and over half of that is
pediatrics. We have children coming to us from all over the
country. They have to be fitted in an expedited fashion, receiving
the prosthesis usually within 72 hours from the time they are first
seen. I believe comparable things are being done by other specialty
teams around the country.
Miguelez: I think the biggest advance that we
see is the expedited delivery and fitting protocols. The old model
for patient care in upper-limb prosthetics involved an initial
meeting with the prosthetist, who took the cast and essentially
told you what you were going to get. In two weeks the patient
returned for a fitting with a test socket; in another two weeks the
patient returned again for the fitting of the prosthesis, followed
by adjustments and harnessing, so the process took from six to
eight weeks. Patient involvement in terms of choice of prosthesis
and how it is fit was minimal.
Not only were these repeat visits to the office difficult and
expensive for the patient, but during this time, residual limb
changes were taking place. As a result a lot of patients
discontinued use since their prosthesis never fit and maybe wasn't
the appropriate prosthetic option.
In our system, we do a very comprehensive prosthetic evaluation,
which involves our psychologist, who [tries to] figure out how the
patient learns and helps us tailor a rehab plan to maximize his or
her learning abilities. The occupational therapist is also involved
in the evaluation and develops a therapeutic plan. If there are
medical complications such as edema or nerve issues, a physician is
also involved.
Typically we spend two to three hours in the evaluation process,
exploring and discussing all the prosthetic options. We let
patients see and touch them, before we arrive together at a game
plan, including the best prosthetic choice for that patient.
In our system, the patient is the hub of the wheel, and the rest
of the team are the spokesso patients really have a feeling of
control, which tends to encourage more buy-in and greater
commitment to fulfilling the rehab plan.
Following through on the expedited program, the patient
typically receives his or her prosthesis within one to three days.
The casting and test socket fittings occur within a few hours of
each other, rather than taking weeks. Adjustments are made along
the way as the patient progresses through therapy, with the
prosthesis being modified as needed.
Editor's note: Payers are increasingly demanding outcomes data.
Why have outcomes measurements been so elusive in upper-extremity
prosthetic care? To read our panel's answers in an exclusively
online article, visit www.oandp.com/edge/issues/articles/2003-01_09.asp
. In upcoming issues, our panelists will discuss, among other
subjects, exciting future trends in upper-extremity prosthetics,
thinking "outside the box," and their personal vision and goals for
the upper-extremity field. Judith Otto is a freelance writer based in Holly Springs, Mississippi. 
Table Of Contents - January 2003
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