The use of conformal lattice metamaterials for relieving stress in lower limb sockets: A numerical and exploratory study.

Selecting the correct material for each application has always been important. Now, with lattice metamaterials engineers can take advantage of the properties of these metamaterials to best suit a specific application. This paper investigates transtibial lower limb socket stress reduction through the implementation of conformal lattice metamaterials. In this work, a model was obtained with a 3D scanner from a plaster cast taken from a participant with a trans-tibial amputation. Then a 3D socket model was created and two conformal patterns were added to the surface of the socket using nTopology®. Parametric studies to relate the lattice metamaterials constituent elements to their effective structural properties, when such are loaded in-plane and out-of-plane were also included. Pressure test simulations were performed to determine the stresses produced in the sockets. This study concludes with discussion of the results and provides information on how surface conformal patterns can improve socket performance, showing that surface-vertex-centroid patterns increase stiffness and relieve stresses.

ARACAM: A RGB-D Multi-View Photogrammetry System for Lower Limb 3D Reconstruction Applications.

In the world, there is a growing need for lower limb prostheses due to a rising number of amputations caused primarily, by diabetic foot. Researchers enable functional and comfortable prostheses through prosthetic design by integrating new technologies applied to the traditional handcrafted method for prosthesis fabrication that is still current. That is why computer vision shows to be a promising tool for the integration of 3D reconstruction that may be useful for prosthetic design. This work has the objective to design, prototype, and test a functional system to scan plaster cast molds, which may serve as a platform for future technologies for lower limb reconstruction applications. The image capture system comprises 5 stereoscopic color and depth cameras, each with 4 DOF mountings on an enveloping frame, as well as algorithms for calibration, segmentation, registration, and surface reconstruction. The segmentation metrics of dice coefficient and Hausdorff distance (HD) show strong visual similarity with an average similarity of 87% and average error of 6.40 mm, respectively. Moving forward, the system was tested on a known 3D printed model obtained from a computer tomography scan to which comparison results via HD show an average error of ≤1.93 mm thereby making the system competitive against the systems reviewed from the state-of-the-art.