Soft tissue control during hydrostatic shape capture for trans-tibial prosthetic provision

Current methods of prosthetic socket design are inadequate. A socket that fits well should demonstrate minimal longitudinal displacement from mid-stance through swing phase of the gait cycle and minimal rotational and transverse movements. To eliminate these issues, the socket should match the surface and volume of the residuum. Of the various methods for creating a prosthetic socket, hydrocasting is the only one which offers volume- and surface-matching under load bearing conditions that are analogous to the stance phase of the gait cycle. However the uniform pressure forces the soft tissue of the stump to redistribute causing the residuum to be shorter and wider. The socket produced from this design method will not demonstrate volume- and surface-matching during swing; this mismatch causes longitudinal displacement, a phenomenon known as pistoning. A Chinese finger trap weave prototype and a polyethylene cylindrical mesh prototype embedded in silicone were developed and tested for radial grip, forces measured on analogue limb, and proximal-to-distal displacement. 3-D CAD models of the weave and mesh were built and tested for radial grip and displacement using an FEA plugin. The data from the empirical grip test was invalid for technical errors. The weave alone was the most successful prototype in empirical displacement testing; this prototype experienced the largest and most consistent displacement in relation to applied tension. The 3-D CAD models were completed, but could not be tested due to time constraints. Future work will include experimenting with different embedding materials; 3-D CAD models will be modified and simulated.Current methods of prosthetic socket design are inadequate. A socket that fits well should demonstrate minimal longitudinal displacement from mid-stance through swing phase of the gait cycle and minimal rotational and transverse movements. To eliminate these issues, the socket should match the surface and volume of the residuum. Of the various methods for creating a prosthetic socket, hydrocasting is the only one which offers volume- and surface-matching under load bearing conditions that are analogous to the stance phase of the gait cycle. However the uniform pressure forces the soft tissue of the stump to redistribute causing the residuum to be shorter and wider. The socket produced from this design method will not demonstrate volume- and surface-matching during swing; this mismatch causes longitudinal displacement, a phenomenon known as pistoning. A Chinese finger trap weave prototype and a polyethylene cylindrical mesh prototype embedded in silicone were developed and tested for radial grip, forces measured on analogue limb, and proximal-to-distal displacement. 3-D CAD models of the weave and mesh were built and tested for radial grip and displacement using an FEA plugin. The data from the empirical grip test was invalid for technical errors. The weave alone was the most successful prototype in empirical displacement testing; this prototype experienced the largest and most consistent displacement in relation to applied tension. The 3-D CAD models were completed, but could not be tested due to time constraints. Future work will include experimenting with different embedding materials; 3-D CAD models will be modified and simulated