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

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 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

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.

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

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

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

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

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

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