The forces applied to the prosthesis during human activity produce dynamic stresses varying in time and may causing stress shielding in prosthesis-bone system. Therefore, it is important to reduce stress shielding effect. This study aimed to investigates, using finite element analysis, how a PEEK and carbon/ PEEK composite coating materials on a titanium alloy hip implant stem could reduce stress shielding effect corresponding to different human activities: standing up, normal walking and climbing stairs under dynamic loadings to find out which of all these models have a better performance. A 3D finite element model of femur, hip implants, coating layers with composite (carbon/PEEK) and polymeric (PEEK) coating materials were constructed for finite element analysis. A time-dependent cycling load was applied on the prosthesis head. The maximum increase in load transfer to the bone was 207% for the prosthesis coated with carbon/PEEK configuration I (fibers orientated with 0, +45,-45, and 90 degrees) in average compared to uncoated one. Numerical result showed that the carbon/PEEK composite material (configuration I) seems to be a good solution to distribute the applied load and transfer it to the bone, thus to reduce stress shielding problems and to prolong lifetime of the prosthesisbone system. It will prevent aseptic loosening and enhance the stability of the system.

This study focuses on the drop foot case related to hyperthyroidism of the ankle joint resulting in the relaxation of the toes during walking. This condition requires treatment using an ankle–foot orthosis. Traditional orthosis techniques lack precision and depend on the skill of the fabricator. This research aims to make a bias in ankle–foot orthosis design and analysis methods, where a complete methodology of numerical design and testing has been proposed using advanced engineering software. A numerical model of the patient’s foot was generated and used to design an ankle–foot orthosis model using SolidWorks. The designed model was mechanically analyzed by the finite element method using ANSYS Workbench 16.1 under different static and dynamic loading conditions. The ankle–foot orthosis model was numerically designed and analyzed before the manufacturing process. This is believed to reduce time and material loss and foster the use of numerical models in biomedical applications. This study suggests focusing on the design and analysis of orthoses according to the patient’s measurements. This is expected to increase the comfort and raise the level of treatment. Numerical design methods also enable precise manufacturing using computerized devices such as three-dimensional printers.

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