Journal of Surgical Simulation 2018; 5: 87 - 98
Published: 14 January 2019
Tunable 3D printed multi-material composites to enhance tissue fidelity for surgical simulation
Background and aim: Medical simulation is an important component in surgical education. Unfortunately, there are very few 3D printed materials that have the tissue fidelity needed for enhanced learning of cardiovascular surgical techniques. Therefore, we sought to determine if we could develop 3D printed composites to better reflect the tissue mechanical properties of the ascending aorta.
Materials and method: 3D printed composites were created using commercially available materials for a Connex3 Objet500 3D printer (Stratasys, Eden Prairie, USA). Support material (SUP705) as well as rigid zigzag Vero fibres were systematically combined with an elastic polymer (TGPF930). The mechanical properties were evaluated in equi-biaxial tensile (tensile stiffness and viscoelasticity), nano-indentation (compressive stiffness) and suture retention strength (strength) (SRS) tests for comparisons with normal ascending aortas (AA) and ascending aortas with aneurysm (AA aneurysm).
Results: Compared with TGPF930 (unpaired t test), the insertion of support material reduced the SRS (TGPF930: 4.45 ± 0.49 N, n = 3; TGPF930 + SUP705, 2.57 ± 0.32 N, n = 3; P = 0.0023) and compressive modulus (TGPF930: 0.61 ± 0.08 MPa, n = 6; TGPF930 + SUP705: 0.38 ± 0.06 MPa, n = 6; P = 0.0002). Embedding Vero fibres increased the SRS (TGPF930: 4.45 ± 0.49 N, n = 3; TGPF930 + Vero: 5.39 ± 0.65 N, n = 3; P = 0.0037), compressive modulus (TGPF930: 0.61 ± 0.08 MPa, n = 6; TGPF930 + Vero: 0.85 ± 0.07 MPa, n = 6; P = 0.0003) and allowed for tuning the mechanical directional dependency of the composite. When all three components were combined, similarities were found with aortic tissue in terms of SRS (three-material composite: 4.25 ± 0.67 N, n = 3; AA aneurysm: 5.31 ± 2.71 N, n = 3; P = 0.6177) and compressive modulus (three-material composite: 0.39 ± 0.03 MPa, n = 6; AA aneurysm: 0.36 ± 0.12 MPa, n = 4; P = 0.4485).
Conclusion: The study has shown that the insertions of fibres and/or support material in a TGPF930 structure can control the mechanical properties of the 3D printed composites. We were able to simulate ex vivo passive tissue characteristics of aortas, therefore improving on the current homogeneous 3D printed TGPF930 material often used in surgical education.
surgical simulation; 3D printing; simulation; ascending aortic tissue; biomechanics; 3D printed composite