Validation of a kidney model made of N‐composite gel as a training tool for laparoscopic partial nephrectomy

DOI: 10.1111/iju.14240 To ensure patient safety, it is necessary for surgeons to practice surgical procedures before carrying them out. In addition, to improve their skill levels and shorten learning curves and procedure times, surgeons are required to practice procedures outside of the operating room. Simulation tools meet such demands. LPN is now considered to be the standard treatment for small kidney tumors. However, mastering this technique is difficult. RICOH (Tokyo, Japan) have produced a kidney tumor model made of N-composite gel. As this is a translucent material, the model makes it possible to visually confirm the internal structure of the kidney. In addition, although it is soft, N-composite gel is elastic and so feels similar to a real kidney. The aim of the present study was to examine the effectiveness of this model as a tool for practicing LPN. In this observational study, medical interns, urology residents and attending urologists were recruited from our institution and consented to participate in the study. The participants were categorized into laparoscopic novices (<20 laparoscopic procedures completed) and laparoscopic experts (>20 laparoscopic procedures completed and having the appropriate surgical skill qualification issued by the Japanese Society of Endourology). All of the participants first watched a brief orientation video demonstrating the task associated with the training model. Both groups carried out the procedure three times. The kidney model included a white urinary tract, yellow tumor and translucent renal parenchyma made of N-composite gel (Fig. 1). The training consisted of two tasks – tumor excision and renal reconstruction. After completing the procedure, all participants completed a questionnaire that assessed the realism of the model (face validity) and its utility as a training tool (content validity) based on 5-point scales (1 being worst and 5 being best). All performances were recorded and scored in a blinded fashion by a single expert surgeon. The participants’ performances were scored based on the GOALS system. In addition to the expert scoring, objective parameters, such as excision and reconstruction time, tumor margin status, maximum gap between the two sides of the incision, and total split length (total length of the split in the kidney), were recorded. A total of 16 participants were recruited for this study, including eight novices and eight experts. The results of face and content validity are shown in Table S1, and were considered to be high (total face average 3.8 and total content average 4.2). The results regarding the construct validity are shown in Table S2. Significant differences in total procedure time and GOALS score were detected between the novices and experts (3848 s vs 2767 s and 30.5 vs 64.5). This indicates the construct validity. As for the improvement from the first to third procedures, significant improvements in excision and total procedure time were detected in novices compared with experts. Thus, the novices showed greater improvements in skill level. The results of comparisons between the first and third procedures in each group are shown in Figure S1. In the novice group, significant improvements in excision and total procedure time were seen from the first to third procedure (666 vs 355.5 s and 1527.5 vs 1173.5 s). Even in the expert group, cutting time was improved (435.5 vs 263.5 s). However, suturing time was not shortened in either group. We believe three practice sessions yielded a training effect for cutting technique, but that more practice is required for improvement of suturing technique. This study had several limitations. The model is less realistic than an animal kidney. For example, no bleeding occurs during the procedure, because it does not include blood vessels. Various reports have described surgical training involving porcine kidneys and silicone models. Practicing surgical techniques using animals will become increasingly difficult, due to the cost implications and the associated ethical issues. Therefore, it is important to develop