Testing of Compliance in a Prosthetic Socket Fabricated Using Selective Laser Sintering

Solid freeform fabrication techniques offer potential as manufacturing technologies in applications that require custom design. One such application is the fabrication of prosthetic sockets. This paper reports on research to manufacture compliant below-the-knee prosthetic sockets using selective laser sintering (SLS). Compliance in the socket is a critical factor in the level of comfort the amputee experiences during gait. The ability to control local geometry is seen as an advantage of SLS in fabricating compliant sockets. This paper presents work on developing a model of compliance for sockets constructed of Duraform®. The approach taken here is to provide the necessary compliance by controlling the wall thickness of the socket. To select the right thickness, a study of the wall deflection with respect to contact pressure was performed. An experimental testing device was designed and constructed to test the deflection versus pressure for different thicknesses of test circular discs made of Duraform®. The results were correlated to a finite element model. These results will be used for designing the compliance in the walls of prosthetic sockets fitted to actual patients.