Visualization of parenchymal deformation during renorrhaphy: a novel deformation index in a simulated kidney model

The objective of this study is to evaluate mechanical tension on the renal parenchyma during partial nephrectomy using a novel index and compare the effects of different suture techniques on strain in a simulated model. A kidney-shaped urethane resin model with surface markers was created to measure deformation. Three-dimensional scanning assessed deformation before and after suturing. Strain values were calculated using finite-element shape functions on a triangular mesh. Distance from the centerline of the suture was also measured. The standard suturing method was defined as continuous stitches using self-retaining barbed sutures. Based on this standard, variations were introduced in suture material, suturing technique (continuous or interrupted), number of stitches, and the distance from the defect edge. Seven suture patterns were tested. Deformation values were higher when sutures were placed farther from the defect margin and lower when placed closer. Interrupted, tight, sparse, and multifilament suture patterns produced strain values similar to those of the standard technique. Narrow suture pattern tended to have longer distances from the centerline than the wide suture pattern. Interrupted and multifilament suture patterns also showed slightly longer distances than the standard pattern. This is the first study to visualize and quantify strain distribution during renorrhaphy using deformation values. The findings suggest that the distance of suture placement from the limbus may impact parenchymal strain. Despite limitations such as a small sample size and use of simulated models, these results offer insights into optimizing renorrhaphy techniques to minimize tissue stress. Future studies with larger sample sizes are warranted.