1. Christine Bronikowski, Amanda Chen, Jared Mulford, Amy Ostrowski
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

2. 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

3. Project Goals
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 cross-section of the surface between the residual limb and socket
Increase overall patient comfort

4. Current Socket Designs
Designed on a case-by-case basis for individual patients
Figure 1 shows a prosthetic that has a firm, rigid shell that provides support and a flexible inner part, which accommodates comfort. This design was easy to make and accounted for the forces and comfort.
Figure 2 has both rigid and flexible regions, but rather than two separate cases, it is all built in together. This socket takes longer to construct and is rather heavy.
Figures 3 are all similar to one another, but the softness of the material varies greatly and the parts that are cut out from the prosthetic also vary. The regions that are cut out correspond to areas that do not need as much support.

5. Method of Force Analysis
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

6. Current Work Circuit design: current to voltage converter
Talk about which one chose and why

7. Design/Safety Considerations
Sensitivity/saturation of FSR may not be within desired force range
Wire thickness: thin enough to prevent interference with force data
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
Talk about epoxy

8. Future Work
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
Standardize patients, measure lenth of leg

9. Determination of Success
Design is patient-driven
Survey and level of comfort pre and post new socket

10. References