A novel suture-free nephroplication with 4D-printed biodegradable bag for giant hydronephrosis: initial experience from hydromechanics and clinical application

Background: Giant hydronephrosis as an rare condition is often caused by chronic ureteral obstruction. Nephroplication is a crucial procedure to improve urinary drainage in the kidney-sparing surgery for patients with giant hydronephrosis. However, traditional nephroplication via suturing kidney has technical difficulty and many potential risks. Materials and methods: We devised a novel suture-free nephroplication by using a 4 dimension (4D)-printed biodegradable bag. Structures of the bag were observed by a scanning electron microscope. Hydromechanical analysis was conducted to explore the mechanism of this novel surgery. Patients with giant hydronephrosis caused by ureteropelvic junction obstruction (UPJO) were recruited. Computed tomography (CT) and renal emission computed tomography (ECT) were used to evaluate the renal morphology and function in preoperative examination and follow-up. Results: 4D-printed biodegradable bag was fabricated using polycaprolactone (PCL). Hydromechanical analysis indicated that reduced space of renal pelvis after the nephroplication could improve urinary drainage. Finally, three patients were recruited, and underwent this novel suture-free nephroplication successfully. Postoperative CT and renal ECT performed at three months after the operation revealed significant recovery of affected kidney. Among them, the glomerular filtration rate (GFR) of affected kidneys in two patients increased from less than 10 mL/min to 13.11 mL/min and 14.30 mL/min respectively, indicating the significant recovery of split renal function. Conclusions: This is a novel suture-free nephroplication for treating benign giant hydronephrosis, in which the 4D-printed biodegradable bag simplified and standardized surgical procedures significantly. Initial experience from clinical application is encouraging, suggesting that the nephrectomy for patients with benign giant hydronephrosis might be avoided. Future investigations on long-term outcomes of this new surgery are warranted.