Optimization of a novel external fixator for orthopaedic applications

摘要

The use of external fixation devices is a very common method for the treatment of bone fractures. However, these fixators present some limitations in terms of mobility, significant risk of infection, and induce pain and discomfort. Moreover, they are also not fully customized to suit individual patients. To avoid these limitations, this paper presents a novel patient-specific external fixator developed using reverse engineering, finite element analysis and additive manufacturing. The fixator was designed based on a set of computer tomography (CT) scan images of a patient and optimized considering different thickness values and materials. New lightweight designs were produced through a manual process (regular distribution of circular and hexagonal voids) and topology optimization. Different polymeric materials (Polylactic acid (PLA); Acrylonitrile butadiene styrene (ABS) and Polyamide (PA)) were also considered for the fabrication of these designs. It was found that although both PLA and ABS allow to meet the design requirements, and that the best mechanical properties were obtained with fixators made of PLA. Results also showed that the best results in terms of mechanical performance and weight reduction was obtained with topology optimization.