INTRODUCTIOND istal radius fractures are traditionally treated with plaster casts. Although this has been the gold standard for treatment for years, it also comes with disadvantages. These are the weight, not being water-resistant and a lack of ventilation, leading to skin problems, itching and compromised hygiene. Furthermore, plaster has no possibility for visual inspection of the skin, while up to 30% of all treatments with plaster casting lead to, mainly skin related, problems. With 3D printing, a lightweight, waterproof, open latticed and personalized cast can be created to overcome the issues with plaster casting. Multiple start-ups, researchers and other individuals already created these 3D printed casts, however, there is no consensus about the materials and design that should be used. Also, implementation of these 3D printed wrist casts into clinical practice stays out. The main research goal is to investigate the feasibility of in-house design, production and implementation of 3D printed wrist casts for the treatment of distal radius fractures. METHODS To answer the main research question, multiple sub studies were performed. First, design requirements were formulated in consultation with clinicians. Then, material tests were performed, followed by creating a design workflow. Subsequently, the optimal design pattern and validation of the stabilization requirements were investigated during a mechanical phantom study. Also, to affirm adequate ease of use and comfort, a comfort study was carried out. The final step was a pilot study, in which the necessary alterations in the workflow were investigated, as well as clinical outcomes and patient experiences. RESULTS The material tests showed that color resin, printed with an SLA printer is most suitable for the production of 3D printed wrist casts. A semi-automated design workflow was created in which a 3D printed wrist cast can be produced within 24 hours. A 3D printed cast with a Voronoi design pattern is most successful for adequate wrist immobilization, achieving similar stabilization abilities as a plaster cast. Furthermore, the comfort study showed that the 3D printed wrist casts ensure adequate comfort, with a mean score of 8.1 out of 10.0 and sufficient ease of use. During the pilot study, two children with greenstick or buckle/torus fractures were successfully treated with the wrist casts. To implement the treatment of distal radius fractures with 3D printed wrist casts into the current workflow, a workflow as used for traditional treatment during the evenings and weekends is required. CONCLUSIONA customized, lightweight, water-resistant and ventilated wrist cast can successfully be designed, with adequate stabilization abilities. This cast can be produced within 24 hours, with the use of a semi-automated design algorithm that creates a wrist cast with ventilation holes based on a Voronoi pattern. The 3D printing should be performed with an SLA printer, with the use of color resin. The produced wrist casts ensure adequate comfort and ease of use and can be implemented clinically for successful treatment of children with greenstick and buckle/torus fractures. Only small alterations are necessary in the current workflow to allow for the production of the 3D printed wrist casts. No extra hospital visits are required and the new workflow is comparable to the weekend workflow. Further research is necessary to tackle the unfavorable cost-effectiveness and the adaption of the casts to swelling. For the future, treatment with 3D printed casts should be extrapolated to unstable fractures, other body parts and the field of orthotics.

Background The current workflow for the design and production of patient-specific surgical guides at the Elisabeth-TweeSteden hospital is out-sourced to external companies, making it a time-consuming and costly task. In order to minimize the production time and expenses, the design and fabrication of these guides could be implemented into the hospital’s workflow using an in-house available 3D printer. Compared to the current gold standard for the production of patient-specific surgical guides, a different printing technique and 3D print material will be used. Therefore, it should be determined whether these are suitable for the production of the guides. Moreover, the 3D printed models must be compatible with the in-house sterilization method in order to ensure quality and reliability. The aim of this thesis was to investigate the effect of the in-house available sterilization method on the mechanical, dimensional, and sterility properties of a novel biocompatible 3D printing material. Methods and results BioMed Clear resin specimens were tested according to the ISO standards for mechanical testing of plastics. Overall, steam sterilization changed the mechanical properties of the material, making it stronger and stiffer but more brittle, as compared to unsterilized specimens. The dimensional tests indicated that sterilization resulted in a dimensional change, up to 0.12 mm, which mostly occurred in the small crevices of the model. The deviations of the dimensions of the resulting 3D printed model compared to the digital 3D model were roughly less than 0.3 mm, which is comparable to the accuracy of the gold standard material, polyamide 12. Sterility tests showed that sterilization of the 3D printed models is indeed mandatory for the guides to be used intraoperatively. Also, the Central Sterile Services Department of the hospital is able to deliver sterile medical devices that can be stored for a minimum of four weeks at the sterile storage room. Conclusion With the feasibility confirmed for the hospital to be able to design and produce patient-specific surgical guides in-house, it is necessary to stress that the hospital must meet the Medical Device Regulations by complying with an appropriate quality management system, documenting the manufacturing process, evaluating the performance, and reviewing the experiences from clinical use.