Purpose of the Work. The goal of this project is
to design and develop an ultrasound-based 3-D imaging system
for computer-aided prosthetic socket design.
Subjects/Procedures. The design and operation of the
system are described. An emphasis is laid on the principle
of reconstructing the skin surface of the limb using a
vertical scan mode. The measurement accuracy of the system
is tested using a cylindrical phantom and a custom-made limb
model. Results. The errors in measuring the diameter
of the phantom and the volume of the limb model are found to
be less than 1 percent. Relevance to the Veteran
Population. The new system provides a safe and low-cost
mean of acquiring both the external shape and internal bony
structure of a residual limb. It is expected that such a
system can help prosthetists to improve the quality of
design-fitting of prosthetic sockets.
Ping He, PhD, PE
Purpose of the Work. The objective of this study
was to determine if new canes could be created that would
improve the wrist/forearm alignment. The purpose of these
canes would be to decrease the impact of repetitive stresses
on the arm and increase biomechanical efficiency.
Subjects. Healthy adults walking with a knee
immobilizer. Procedures. Subjects were wired with
surface electromyography (EMG) electrodes, which recorded
the electrical voltage emitted by muscles in the arm during
stance and gait with different walking canes.
Results. Results showed that using these alternative
canes decreased the EMG voltage of the arm as compared with
the standard cane. Relevance to the Veteran
Population. As the veteran population lives to be older,
there are more chronic cane users. We plan to design better
canes that limit trauma to the arms. It is hoped that doing
so will lessen the chance of carpal tunnel syndrome and
osteoarthritis.
Faye Chiou-Tan, MD
Purpose of the Work. It is important to know
whether veterans can make effective use of their prostheses.
The area has never been studied through a survey so a pilot
was conducted. Subjects. All 170 US soldiers (a) who
had traumatic amputations over the last ten years whose
addresses were supplied by the VA and (b) whose medical
synopses showed them to be otherwise healthy when leaving
the military. Procedures. A survey of prosthetic
problems was sent to the above veterans. Results.
Although only 45 veterans responded (26%), all had
significant problems using their prostheses for work and
most had other problems as well. Relevance to Veteran
Population. The group surveyed were relatively young and
healty so were the least likely to have problems using their
prosthetics. As they had significant problems, it is highly
likely that the majority of veteran amputees also have
significnat problems. The situation should be investigated
through a large survey.
Richard A. Sherman, PhD
Purpose of the work. This study describes the
development of a test defining the relationship between skin
blood flow and increasing surface pressure to evaluate the
effect of a pressure-induced lack of perfusion over a 5-hour
period. Subjects/Procedures. Pressure was applied to the
hips of the fuzzy rat (almost hairless), using a
computer-controlled plunger that pressed on the skin while
measuring blood flow with a laser light shinning through the
center of the tip of the column during the application of
pressure. Pressure was increased in 10-g steps (each step
lasting 30 s) until average blood flow was reduced to
zero, then pressure was released. This test results in a
characteristic blood flow pattern for healthy skin. The
complete experimental design consists of the application of
the test before and after an experimental intervention
(5-hours of reduced perfusion to skin). Results. The 5-hour
pressure-induced cut off of blood flow resulted in major
changes to the normal perfusion pattern of the skin which
could adversely affect the ability of the skin to return to
normal and resist infection. Relevance to the Veteran
Population. This test has application for evaluating the
effect of treatments or interventions affecting skin tissue
breakdown and pressure-induced ulceration. Pressure ulcers
are a major secondary medical condition with significant
impact on important veteran populations including the spinal
cord injured and the aged.
James Donofrio, PhD
Purpose of the Work. This study investigated the
effects of spinal cord injury on the ability of an
individual to withstand the braking forces experienced
during normal driving. Subjects/Procedures. A manual
wheelchair was secured to a platform that rotated forward to
challenge the upright posture of the subject. Individuals
with tertaplegia, paraplegia, or no injury participated in
the study. Results. Without the use of the arms,
almost all of the spinal cord-injured subjects became
unstable at force levels below those seen during normal
driving. Among the spinal cord-injured subjects, injury
level was not always a good predictor of stability.
Relevance to the Veteran Population. Trunk stability
during even normal driving conditions may be compromised.
Restraint of the pelvis and lower torso may improve
stability without restricting movement of the upper torso
and arms. Adaptive driving controls should be examined to
verify that their performance is unaffected by the forces
inevitably placed upon them in an effort to stabilize the
upper body.
Derek Kamper, PhD
Purpose of the Work. This research examined the
mechanical effects of static versus cyclic pressures of
human skin. Procedures. Static or cyclic pressures
were applied to healthy, newborn skin. The pressures used
were based on interface pressure readings from human
subjects resting on various support surfaces. The skin was
tested in tension after being subjected to pressure.
Results. Skin subjected to pressure prior to tensile
testing was less stiff than control tissue. The mechanical
properties of tissue subjected to static pressure were
altered more than tissue subjected to dynamic pressure.
Relevance to the Veteran Population. The findings of
this study suggest that pressure has a direct effect on the
mechanical properties of the skin. Changes in the mechanical
properties of the skin may contribute to the formation of
pressure ulcers.
Laura E. Edsberg, PhD
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