Experimental determination of the suture behavior of aortic tissue in comparison to 3D printed silicone modelling material.

The imitation of biological tissue in a synthetic physical model can benefit many medical applications, e.g. pre surgical planning or education. For a quantitative validation of the model's mechanical behavior, standardized testing on both, the biological original and the artificial material, is necessary. In four parts, this study focuses on the biomechanical analysis of the impact of sutures for aortic modelling using 3D printed silicone. Testing methods are developed and executed on biological and synthetic samples. The first part is the determination of the pullout strength of a single stitch. The second part is the investigation of the reduction of the tensile strength and elongation of tensile bars due to stitching. Third, the tensile testing of biological and artificial vessels repaired with an anastomosis gives information about the transferability to real surgical applications. A qualitative feedback study with surgical experts concludes the evaluation. The study reveals that the pullout strength is independent from the fiber or notch direction, but that repaired aortic tensile bars show a dependency on the fiber direction of the tissue. Additionally, the circular seam of the anastomosis provides a more stable connection than multiple single stitches. For the artificial models, the mechanical behavior mainly depends on the mechanical properties of the base silicone, here represented by the Shore A hardness, rather than the manufacturing process. When compared to the biological original the most similar material varies depending on the mechanical property in focus.

Design and fabrication of a generic 3D-printed silicone unilateral cleft lip and palate model.

The complexity of plastic surgery procedures often requires visualization of the anatomy in three dimensions and therefore demands the development of new and innovative teaching methods. This work describes the development and manufacture of a 3D silicone cleft lip and palate (CLP) model evaluated by surgical residents on its similarity to the biological model. Thirty unilateral CLP models were created and distributed to residents at two different institutions. The model was based on an adult CT scan that was manipulated to resemble an infant with a complete unilateral CLP. This digital model was directly printed in silicone elastomer pieces and later assembled. The residents rated the model based on its realistic value as well as whether or not they felt it improved their surgical technique. Twenty residents used the model to simulate a CLP repair. The structure of the model was rated as fairly realistic while both the material and assembly of the model require improvement in subsequent manufacturing. Post simulation, residents rated the model highly for how accurately it simulated the surgical procedure. An accurate 3D silicone unilateral cleft lip and palate replica was successfully created for educational purposes. This new approach combines a flexible generic design with automated manufacture.

Experimental Mechanical Examination of Artificial 3D Printed and Post Processed Vascular Silicone Models.

Anatomical models have gained increasing visibility over the last years. Their application in surgical education could have a great impact and many benefits. Vascular haptic models consist of soft materials like silicones, which can be 3D printed for complex geometries. This study focuses on quantifying mechanical behaviors as tensile strength, elongation and Shore A hardness for healthy and pathological silicone based vascular models. The quantification enables a more specific modelling of vessel properties, which leads to a more accurate simulation and therefore better education.