Impact of pressure distribution on the relief areas of prosthetic sockets for transtibial amputees using design of experiment and finite element analysis

Abstract

The design of experiment (DOE) tool and finite element method (FEM) are very powerful for analyzing and optimizing the behavior of structures in a complex mechanic and geometry. In prosthetic sockets, great flexibility with a long range of spring-like action is needed. A finite element analysis was conducted investigating the stress and displacement distribution for different cases of Duraform (durable polyamide) and UHMWPE (ultra-high-molecular-weight polyethylene) sockets where relief was needed in certain pressure distribution areas experienced by the patient. A DOE using two-level factorial design was used to optimize these areas. Stresses and displacements were included in the model, and the desirability function was calculated. Higher deformation of the pressure relief areas was sought while preserving the socket structural integrity. Six socket cases associated with two different materials having 3 and 5 mm overall thicknesses were analyzed by FEM, and stresses and displacements of the five pressure relief areas were evaluated for all cases. High deformation of the socket relieved areas was optimized using DOE to assure the comfort of the amputee. The structural integrity of the socket and the optimized responses values with high desirability of the DOE model implied that Duraform socket A with 1.69 mm relief area could be the best design scenario for all cases.