Transcript Oral Presentation

Analyzing the forces within
transtibial prosthetic sockets
and design of an improved
force minimizing socket
Christine Bronikowski, Amanda Chen, Jared
Mulford, Amy Ostrowski
Advisor: Aaron Fitzsimmons, The Surgical Clinic
Problem Statement

Lack of research in the socket interface between
the artificial limb and the residual limb,
specifically force profiles
 Majority of the research focused on components
with higher potential financial gains
 Problems with skin irritation, varying degrees of
pain, tissue breakdown, pressure ulcerations,
and resultant infections at the socket interface
develop
Project Goals

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Acquire accurate measurements of the forces
acting on the residual limb of an amputee
during various movements
Determine areas of highest force
Design a socket system in which the forces
are optimally distributed throughout the crosssection of the surface between the residual
limb and socket
Increase overall patient comfort
Current Socket Designs

Designed on a case-by-case basis for individual
patients
Method of Force Analysis
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Force Sensing Resistor (FSR) placed directly in socket
Very thin-will not cause variation in force determination
Change in resistance when force is applied, converted
to a voltage difference
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Current Work

Circuit design: current to voltage converter
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Design/Safety Considerations


Sensitivity/saturation of FSR may not be
within desired force range
Wire thickness: thin enough to prevent
interference with force data

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Thick enough to not break during
movement/walking
FSR-wire connection: must be durable due to
movement of limb

Low temperature solder: must not melt FSR plastic
Future Work
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Insertion of ~15 FSRs into limb-socket interface of
“model” patient, Cody
 Test run: determine if FSR saturates, stays intact,
comfort and safety of Cody
Repeat with ~10 patients
 Rotate FSRs within socket to cover entire area
 Test multiple surfaces (incline, flat, stair)
Analyze results, determine location of maximum force
Design and develop a new socket: provide more
flexibility in areas of greatest force
Determination of Success

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Design is patient-driven
Survey and level of comfort pre and post
new socket
References
Engsberg, J.R., Springer, M.J.N., and J.A. Harder. (1992). Quantif ying interface
pressures in below-knee-amputee sockets. J Assoc Child Prosthet Orthot Clin 27(3),
81-88.
Houston, V. L., Mason, C.P., LaBlanc, K.P., Beattie, A.C., Garbarini, M.A., and E.J.
Lorenze. Prelim ary results with the DVA-Tekscan BK prosthetics socket: residual
lim b stress measurement system. In: Proceedings fo the 20t h Ann ual Meeting
American Academy of Orthotist and Prosthetist, Nashvill e TN. P 8-9
Jendrzejczyk, D. J. (1985). Flexible Socket Systems. Cli n. Prosthet. Orthot. 9 (4), 27-31.
Lee, W.C., and M. Zhang. Using computational sim ulation to aid in the prediction of
socket fit: a prelimi nary study. Med Eng Phys. 2007 Oct;29(8):92 3-9.
Polli ack, A.A., Sieh, R.C., Craig, D.D., Landsberger, S., Mcneil , D.R., and E. Ayyappa.
Scientifi c vali dation of two comm ercial pressure sensor systems for prosthetic socket
fit. Prosthetics and Orthotics International, 2000, 24, 63-73.
Sanders, J.E., Daly , C.H., and E.M. Burgess (1993). Cli nical measurement o f normal
shear stresses on a transtibial stump: Characteristics of wave-form shapes during
walking. Prosthet Orthot Int 17, 38-48.