Patient-specific 3-dimensional Printed Kidney Designed for 4D Surgical Navigation: A Novel Aid to Facilitate Minimally Invasive Off-clamp Partial Nephrectomy in Complex Tumor Cases

Objective To report our initial experience with a novel style of 3-dimensional (3D) printed kidney, which we call "4D" surgical navigation in minimally invasive off-clamp partial nephrectomy (PN). Materials and Methods Ten patients with a R.E.N.A.L. nephrometry score ≥8 renal mass underwent minimally invasive off-clamp PN navigated with the aid of a patient-specific 3D printed kidney. To enhance the advantage of a 3D printed organ, we herein designed our 3D printed kidneys so that the tumor and its margin could be removed. This tumor removability allowed surgeons and patients to preoperatively visualize both the pre- and posttumor-resection kidney status, which we termed "4D" surgical navigation. Before patients consented to surgery, the surgical procedure and perioperative risks were explained to each patient using the patient-specific 3D printed kidney; subsequently, surgeons asked patients whether the 3D printed kidney model had helped them better understand their surgery than they would have without the model. Results All minimally invasive off-clamp PNs were successfully completed with acceptable perioperative outcomes and negative surgical margins. The 3D printed tumors together with their margins were nearly identical to the surgical specimens. All patients responded that their specific 3D printed kidney models had helped them understand their disease and the operations they underwent. Conclusion This is the first report of a novel 3D printed organ style, which we termed "4D" surgical navigation. Use of the current 3D printed kidney models helped surgeons to perform minimally invasive off-clamp PN in complex tumor cases and also helped patients to more fully understand the operation.