[3D-Printed Templates for Physician Modified Endografts - Current Concepts and New Workflows]

Fenestrated or branded prostheses are used to treat complex abdominal aortic aneurysms. In urgent cases, "Physician-modified endografts" (PMEG) are used when delivery times for customised prostheses are long. In this technique, the distances between the fenestrations are measured on the patient's computer tomography data set, manually transferred to the three-dimensional surface of the prosthesis by the surgeon and the fenestrations are cut into the endoprosthesis accordingly. This process is highly dependent on the surgeon's experience. This paper provides an overview of current modification processes and presents a new, simplified workflow to produce a template for modification within 12 hours of receiving the CT data set.Preoperative CT data sets served as the basis for the development of the patient-specific templates. The three-dimensional, individualised templates were to be additively manufactured using a transparent material and placed over the standard tubular prostheses. Due to the transparency of the material and the possibility of rotating the prosthesis within the template, the optimal position of the fenestrations on the prosthesis was to be found independently of experience.Patient-specific templates for modifying prostheses were developed and additively manufactured using CT data (n = 22). For each template design, the segmentation, design and additive manufacturing process could be completed within 12 hours in a standardised manufacturing process. Material transparency, template design and easy handling of the templates permitted the positioning of the fenestrations regardless of experience. Low-resolution CT data sets, extreme curvatures or angles of the aorta were considered exclusion criteria.The patient-specific templates could be created within 12 hours using a standardised procedure with a simple development process. The transparent templates are a further step towards patient-specific medicine.