Development of a Prosthetic Biofeedback Method and Device to Measure Quality of Fit for Trans-Tibial Amputees
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Date
2021-05-27
Authors
Murdock, Robin
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
As the primary interface between the prosthetic and the residual limb, the socket
is a crucial component affecting fit and function of the device. While prostheses
have been used for centuries, prosthetic socket design concepts have remained
stagnant. With the increase in prevalence of obesity and diabetes, amputations
associated with secondary complications have risen as a consequence. In particular,
neuropathy complicates transition of a new amputee to using a prosthetic
socket crucial for their quality of life by reducing -or in some cases completely
hindering- tactile sensation and healing in the residual limb. The objectives of
this thesis are to: 1) create a protocol to evaluate innovative technology within
the socket in vitro while maintaining a true sense of the users limb geometry and
material characteristics that interface with the socket, and 2) develop and validate
a method of providing biofeedback to prosthesis users, particularly those
with neuropathy.The focus of this thesis will be on trans-tibial amputees and
prosthesis to reduce the complexity of including a knee joint and to address the
largest population of amputees.
In this thesis, a method of testing innovations through the use of artificial
biofidelic limbs by systematically varying dimensions was first developed and
validated against in vivo measurement of amputees reported by Silver-Thorn
[15]. Materials characterization yielded closely matching relaxation at 5s to
published values [15]- achieving a range of 22.43-31.94% to that of Silver-Thorn
with a range of 25.35-49.25%. However, full relaxation and size control during
fabrication needs improvement to create a more consistent limb. The max relaxation
being measured as 39.06% against the in vivo measurements reaching
68.03%. Additionally the size of the limbs varied from the model by a maximum
of 13mm.
Following development of the test methods, a method of measuring fit changes
within the socket using a single pneumatic (PicoPress) sensor on the distal end
to measure distal end (or end-pad) contact pressures. Tests using the biofidelic
limbs indicates the use of a single picopress sensor in the distal end is a
viable option to detect fit changes over time. However, settling times need to
be further investigated to identify barriers to dynamic use (e.g. gait during
walking). Feedback from practicing orthotists indicate the PicoPress approach
is a viable option to include in existing fabrication processes used to generate
custom sockets without altering supply lead times and fabrication times.
Description
Keywords
Prosthetic, Trans-tibial, Health, Pressure, Sensing, Bio-feedback, Neuropathy