The prosthetic liner plays a significant role in the redistribution of the pressure between the stump and the socket, as it adding a cushioning layer between the stump and the socket which relieves pain and makes the prosthesis more comfortable. This study employed nonlinear finite element analyses to investigate the peak pressure and shear stress at stump–prosthetic interface in the case of multi-layer prosthetic foam liner, this liner having an inner polymeric foam layer Surrounded by another type of polymeric foam layer, we used three different types of foams in different order to define this liner (flexible polyurethane foam, polyurethane-shape memory polymer foam, and natural rubber latex foam). That’s allows comparing 6 deferent configuration of multi-layer prosthetic foam liner.

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Body pressure dispersion mattresses are useful tools for preventing pressure ulcers in patients with limited mobility who experience prolonged body weight-related compression loads at their body contact areas over time. The objective of this study is to propose and optimize a multicell finite element (FE) model of foam mattress to prevent patients from developing pressure ulcers (bed sores), by improving the contact pressure distribution on the upper mattress surface and immersion in the mattress. The NSGA-II multi-objective genetic algorithm was used to predict different configurations of cell materials to provide a more comfortable sleep. Our mattress model contains many cells (50 × 50 × 50), each of which can contain one of the nine different foam firmnesses. The NSGA-II algorithm attempts to combine the properties of soft and firm foams into a single mattress. however, the complexity and intersection of the fitness function objectives and the high number of possible chances forced the optimal solutions set to extend into the area under the result of foams that have a compressive strength between soft and firm. Based on the overall optimization results, the standard deviation ranged from 0.00325 to 0.00175 MPa and the maximum mattress immersion ranged from 50 mm to less than 20 mm. Mattresses with optimal configurations disperse body pressure smoothly to fit the patient's body shape.

A lot of trans-femoral amputation patients experience skin breakdown due to the pressures and shear stresses in the stump-prosthesis interface. In this study, a finite element model was employed to investigate the stresses at the stump interface in the case of an orthopedic implant fixed to the cut end of the femur. By changing the stiffness of this implant, we aim to see how the stiffness of this implant affects the stresses in the interface between the amputated limb and the prosthesis. To find out the effects of implant stiffness, five values for the elastic modulus, ranging from 0.1 to 0.5 Mpa, with an interval of 0.1 Mpa were employed in the implant structure of the FE model. Obtained results show that the implant played important role in reducing the stresses at the stump-prosthesis interface where the contact pressure did not exceed 53 Kpa and 17.3 Kpa for shear stress in the stiffer case of an implant, while the contact pressure in the case of femur without implant exceeded 79Kpa and 42 Kpa for shear stress. We also noted that the intensity of the contact pressure and the shear stress is proportional to the stiffness of the implant, as the greater the implant stiffness, the higher the peak of these stresses.