Lower limb prosthesis: Optimization by lattice and four-bar polycentric knee.

Diabetes has brought several health problems; one of the most common is the amputation of the lower limb, for which the development of low-cost lower limb prostheses has taken on an important role to allow people with these injuries to continue independently with their lives. This paper proposes developing a transfemoral prosthesis for a 47-year-old patient with a weight of 100kg and a height of 1.80m. The approach shows the kinematic model of the four-bar mechanism of the knee, following the Denavith-Hartenberg method, and the calculation of the knee angle curve and the gait with the help of OpenSim. Consequently, it is shown the design of the parts of the prosthesis done in Autodesk Fusion 360 and their optimization by a lattice in Creo software. Finally, the stress simulations in Ansys with the materials previously selected in CES EduPack are presented.

Identification of Stress Fields in a Customized Mandibular Reconstruction Based on a Photoelastic Model.

Tumors, trauma and infections are the main reasons for subjecting a patient to a bone reconstruction made with the use of bone grafts or prosthetic elements, using for example components such as osteosynthesis plates, meshes and screws for their stabilization.This study focuses on the photoelastic analysis of a customized prosthesis of the jaw for a patient diagnosed with osteonecrosis. A resin model was manufactured as follows: DICOM files were processed in ScanIP software to obtain an STL file that was used to generate an antagonist model of the healthy section of the jaw using CATIA software, then, models were printed in Acrylonitrile Butadiene Styrene (ABS). Following the resin casting technique, the printed model of the jaw was used to construct a resin model, which is tested to determine its mechanical behavior.After carrying out the photoelastic analysis, it was found that the assembly process generates stress concentration zones. Here, the stress reaches a maximum value after the application of a bite force of 130.9 N in the premolars. In this study near the premolars, 3 stress concentration zones were identified and overlap of stress fields is reveled.The results show the importance of planning in the design and assembly process to obtain the best results in the reconstruction, reducing in this way the risk of a surgical reoperation due to problems of rupture or loosening of the prosthesis.

Determination of the mechanical properties of lumbar porcine vertebrae with 2D digital image correlation.

PURPOSE: To evaluate the strain fields and to calculate the modulus of elasticity and Poisson's ratio of trabecular bone of the 6 lumbar vertebrae of the porcine spine by a 2-dimensional digital image correlation (2D DIC). METHODS: This study was performed through a 2D DIC technique and the specimens were tested under compression. The resulting images were analyzed numerically by 2D DIC. Then, representative regions of interest were examined. The strain fields were determined and stress-strain curves were obtained. RESULTS: The full field measurement of the strain in the lumbar bone spine was evaluated and with this data, the Young's modulus and Poisson's ratio were determined. CONCLUSIONS: This research highlights the potential applications of noninvasive acquisition techniques in biomechanical analysis. This is useful in the mechanical characterization of bony structures and in the design of prostheses.