Mechanical and functional validation of a perfused, robot-assisted partial nephrectomy simulation platform using a combination of 3D printing and hydrogel casting

• Published in: World journal of urology Vol. 38; no. 7; pp. 1631 - 1641
• Main Authors: Melnyk, Rachel, Ezzat, Bahie, Belfast, Elizabeth, Saba, Patrick, Farooq, Shamroz, Campbell, Timothy, McAleavey, Stephen, Buckley, Mark, Ghazi, Ahmed
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2020; Springer Nature B.V
• Subjects: 3-D printers; Animals; Compression; Computed tomography; Freeze-thawing; Hemostasis; Hydrogels; Hydrogels - administration & dosage; Image processing; Kidney; Kidneys; Mechanical properties; Medicine; Medicine & Public Health; Models, Anatomic; Nephrectomy; Nephrectomy - methods; Nephrology; Oncology; Perfusion; Polymers; Printing, Three-Dimensional; Robotic Surgical Procedures; Robots; Segmentation; Simulation; Swine; Topic Paper; Urology; Inanimate model; Partial nephrectomy; Simulation; Mechanical testing; 3D printing; High fidelity; Perfused kidney model
• ISSN: 0724-4983; 1433-8726
• DOI: 10.1007/s00345-019-02989-z

Introduction and objectives
There is a scarcity of high-fidelity, life-like, standardized and anatomically correct polymer-based kidney models for robot-assisted partial nephrectomy (RAPN) simulation training. The purpose of this technical report is to present mechanical and functional testing data as evidence for utilizing a perfused hydrogel kidney model created utilizing 3D printed injection casts for RAPN simulation and training.
Methods
Anatomically correct, tumor-laden kidney models were created from 3D-printed casts designed from a patient's CT scan and injected with poly-vinyl alcohol (PVA). A variety of testing methods quantified Young’s modulus in addition to comparing the functional effects of bleeding and suturing among fresh porcine kidneys and various formulations of PVA kidneys.
Results
7% PVA at three freeze–thaw cycles (7%-3FT) was found to be the formula that best replicates the mechanical properties of fresh porcine kidney tissue, where mean(± SD) values of Young’s modulus of porcine tissue vs 7%-3FT samples were calculated to be 85.97(± 35) kPa vs 80.97(± 9.05) kPa, 15.7(± 1.6) kPa vs 74.56(± 10) kPa and 87.46(± 2.97) kPa vs 83.4(± 0.7) kPa for unconfined compression, indentation and elastography testing, respectively. No significant difference was seen in mean suture tension during renorrhaphy necessary to achieve observable hemostasis and capsular violation during a simulated perfusion at 120 mmHg.
Conclusions
This is the first study to utilize extensive material testing analyses to determine the mechanical and functional properties of a perfused, inanimate simulation platform for RAPN, fabricated using a combination of image segmentation, 3D printing and PVA casting.