Pressure redistribution in additively manufactured composite prosthesis by architecture control

Current orthopaedic challenges require the use of advanced technologies to create exoprosthetic limbs. An orthopaedic socket is an important component of the exoprosthesis; in many ways, the functionality of the prosthesis is crucial for the speed of patient is recovery. Application of additive manufacturing technologies in combination with numerical modelling approaches can be successfully applied to create an orthopaedic socket with properties tailored to the needs of a particular patient. An important aspect of the work is the study of mechanics of structured composites in order to achieve the possibility of pressure redistribution by controlling the internal architecture of the prosthesis. This paper is focused on numerical study of the mechanical behaviour of the orthopaedic exoprosthesis socket, produced using additive manufacturing from different types of polymer matrix with embedded carbon fibres. The results obtained will benefit the design of exoprostheses combining the possibility of free architecture achieved with 3D printing capabilities and improved mechanical properties obtained with continuous-fibre reinforcement

Biocompatibility of 3D-printed PLA, PEEK and PETG: Adhesion of bone marrow and peritoneal lavage cells

Samples in the form of cylindrical plates, additively manufactured using the fused deposition modelling (or filament freeform fabrication, FDM/FFF) technology from polylactide (PLA), polyethylene terephthalate glycol (PETG) and polyetheretherketone (PEEK), were studied in series of in-vitro experiments on the adhesion of rat bone-marrow cells and rat peritoneal cells. Methods of estimation of the absolute number of cells and polymer samples’ mass change were used for the evaluation of cells adhesion, followed by the evaluation of cell-culture supernatants. The results of experiments for both types of cells demonstrated a statistically significant change in the absolute number of cells (variation from 44 to 119%) and the weight of the polymer samples (variation from 0.61 to 2.18%), depending on roughness of sample surface, controlled by a nozzle diameter of a 3D printer as well as printing layer height. It was found that more cells adhere to PLA samples with a larger nozzle diameter and layer height. For PETG samples, the results did not show a clear relationship between cell adhesion and printing parameters. For PEEK samples, on the contrary, adhesion to samples printed with a lower nozzle diameter (higher resolution) is better than to samples printed with a larger nozzle diameter (lower resolution). The difference in results for various polymers can be explained by their chemical structure