Lower limb amputation is a severe psychological and physical event in a patient. A prosthetic solution can be provided but should respond to a patient-specific need to accommodate for the geometrical and biomechanical specificities. A new approach to calculate the stress-strain state at the interaction between the socket and the stump of five transfemoral amputees is presented. In this study the socket donning procedure is modeled using an explicit finite element method based on the patient-specific geometry obtained from CT and laser scan data. Over stumps the mean maximum pressure is 4 kPa (SD 1.7) and the mean maximum shear stresses are 1.4 kPa (SD 0.6) and 0.6 kPa (SD 0.3) in longitudinal and circumferential directions, respectively. Locations of the maximum values are according to pressure zones at the sockets. The stress-strain states obtained in this study can be considered more reliable than others, since there are normal and tangential stresses associated to the socket donning procedure.

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As an initial step of this research, open cell magnesium foams were obtained by infiltration casting using a preform of salt particles with irregular morphology. Despite this metallic foam was a successful approach to bone replacement scaffold, the properties of a metal foam need to be improved to meet the requirements by accurately adjusting the porous geometry. The tissue scaffold structure should be submissive biologically as well as mechanically and should at best mimic the natural properties of bone to act as an accurate bone substitute. The architectural and mechanical bone scaffold parameters determine the biological outcome.This work aims to design and manufacture an ordered foam with mechanical and architectural properties similar to those of the bone using an Mg alloy as a base material. Accordingly, representative features were identified to generate computer-aided designed (CAD) unit cells. Then, a set of the selected cells was assembled to obtain a specified architecture for bone replacement. Finite element method analysis was applied to calculate the mechanical response. The architectural parameters were varied to match the elastic properties of human bone concerning suitable exposed area, volume, and pore size. The best architecture was determined by compression loading acting on the assembly. Finally, polymeric stamps with sets of truncated octahedrons will be printed from the CAD model and were replicated in a clay made with a combination of salt and flour. Infiltration casting will obtain last of all, open cell magnesium foams.

Historically, the design and fitting of prostheses had to rely on a slow process of trial and error, depending on the expertise of the prosthetist. Therefore, a clear definition of the concept of comfort and clear knowledge of its contributing factors are important when designing comfortable prostheses. However, there are currently no standardized methods to adequately measure prosthesis-related comfort. The aim of this study is to identify the factors that underlie the concept of comfort with prosthesis use in transfemoral amputees. Forty-one transfemoral amputees completed a questionnaire to evaluate the perception of comfort and to analyze the influence of six factors. It found a significant model that correctly classifies 84.9% of the cases. It can predict whether the patient feels comfort while using the prosthesis. Although all of the factors were significant, the factors with the greatest influence on the perception of comfort were functionality and pain.

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