Research of the implication of Three-dimensional printing technology on kidney surgery
Mar 18, 2022
Contact: Audrey Hu audrey.hu@wecistanche.com
Francesco Esperto, Francesco Pratal & at al.
Introduction
Three-dimensional printing (3DP) has emerged in the late 1980s, but its application in the medical field dates to the 2000s [1]. Until recently, its use was limited mostly to orthopedics and dentistry. As three-dimensional (3D) printers have become more widespread and affordable, a rapid increase in the use of 3DP(Three-dimensional printing) in medicine has been registered. Currently, several types of technologies are available for printing such as binder jetting, material jetting, vat photopolymerization technologies, and powder bed fusion; furthermore, 3D(three-dimensional) printers can now generate objects from different materials such as plastics, wax, ceramics, and metal [2]. In recent years, 3DP(Three-dimensional printing)-technology (3DPT)(Three-dimensional printing technology ) allowed manufacturing models to produce facsimiles of patients’ organs, even entire body parts, to be used for training purposes and to improve surgical planning. Moreover, the introduction of artificial realities created with the help of software (virtual realities VR, augmented realities) represents a further step in 3DPT(Three-dimensional printing technology ) allowing the surgeon to perform guided surgery without giving up concentration on the operating field. The aim of this review is to examine the application of 3DP(Three-dimensional printing) in kidney surgery; in particular, we focus on surgical planning, patient education, training, and augmented reality (AR). 3DP(Three-dimensional printing) and Surgical Planning Pre-operative planning are crucial to improve surgical outcomes and to reduce possible intra- or postoperative complications. 3D (three-dimensional) models (3DM) could play an important role in helping surgeons to properly understand patient-specific anatomy and guiding their intraoperative decisions.3D anatomical replicas printed directly from patients' DICOM images(CT scan or MRI) have been used to aid information in the preoperative planning of complex surgical procedures and trying to reduce perioperative complications[3]. Surgical planning with 3DM(Three-dimensional models) has significant advantages over the current two-dimensional (2D) images. Surgeons have a more realistic overview and better comprehension of the area in which they're going to perform surgery. Possible benefits provided from these models are better decision-making and consequently increased surgical confidence.
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Applications of 3DP(Three-dimensional printing) in Nephron Sparing Surgery (NSS) More than half of the publications about 3DM(Three-dimensional models) in urology re-ported surgical planning as their primary outcome. In the era of nephron-sparing surgery (NSS), due to the complex anatomy and vasculature, the potential prolonged renal ischemia, and the often unclear tumor depth invasion, is not surprising that the majority of studies have focused their attention on kidney cancer [3].
Even if ablative techniques and active surveillance are possible choices in selected patients, surgical treatment for renal masses still represents the gold standard and has evolved, through years, to an NSS approach. Until 2011, there were no studies proving better outcomes of partial nephrectomy (PN)instead of radical nephrectomy (RN)[4]. In 2012, Sun and colleagues demonstrated for the first time that, in multivariable analysis, patients who underwent PN were significantly less likely to die for other-causes mortality (OCM) compared with the RN cohort (p =0.04), stating that PN should be offered "whenever technically feasible"[5]. Nevertheless, feasible does not always mean easy: higher R.E.N.A.L.score masses are more prone to result in higher Clavien-Dindo post-operative complications(p=0.043)and a significant drop in postoperative renal function(p=0.004), due to surgical complexity [6]. Prior to considering surgical outcomes, preoperative planning can strongly be influenced by 3DM(Three-dimensional models), especially in the case of complex renal masses.
Urology has moved from open to minimally invasive surgery (MIS)and from radical organ extirpation to NSS. As a result, surgeons need to rely on models that can give them a better understanding of patients' diseases helping in improving surgical planning. Silberstein et al. in 2014 performed 5 PNs (4 robotic and 1 open) with complete excision of renal masses after creating 5 customized, patient-specific,3D kidney models [7]. The main characteristic of these models was the enhanced renal lesions suspicious for malignancy. In this study, all interventions were successfully performed with an average ischemia time of 21 min, all surgical margins were negative, and complications were minimal. A preliminary report by Zhang et al. showed that in patients with T1 renal masses eligible for NSS,3DMs(Three-dimensional models) had higher scores in surgical planning [8]. Furthermore, the two surgeons involved stated that intraoperative consultation of the 3DM was helpful for the relationship of the tumor with surrounding tissues, depth of resection, and avoidance of key structures injuries such as renal hilum. However, no specific questions regarding how the 3DMs(Three-dimensional models) impacted surgical planning decisions were administered.
After 1 year, Wake et al.selected 10 renal neoplasms scoring more than 5(range 6-10)at R.E.N.A.L.nephrometry score and submitted 2D images before 3DMs(Three-dimensional models) to three experienced urologic oncology surgeons [9]. After submission of models,30-50% of surgeons were prone to change the surgical approach, with the largest impact on transperitoneal or retroperitoneal approach and clamping.
Porpiglia et al.evaluated the usefulness of 3D(three-dimensional) printed kid-ney models and surgeon's perception. Based on their data, 3DMs(Three-dimensional models) seemed to influence surgeons in the choice of the most appropriate type of ischemia(off-clamp vs global ischemia vs partial ischemia) and the type of resection to perform (enucleation or enucleate section) without difference on the basis of surgeons experience [10].
Treatment for kidney disease: Cistanche herb & cistanche extract
However, good planning doesn't always mean good surgical outcomes. Many studies have focused their attention also on results after 3DMs(Three-dimensional models) visualization and to what extent they can influence surgeries. In a feasibility study by Rundstedt et al., a patient-specific presurgical protocol for robot-assisted PN (RAPN)was developed [1].In their study, 10 patients with solid renal masses underwent RAPN after pre-operative rehearsal using 3D(three-dimensional)-printed kidney models made by a silicon-based material.R.E.N.A.L.nephrometry scores were between 7 and 11(mean 8.9). The authors compared the resection times of the model and the tumor. Their results showed no statistically significant difference between the 3DM(Three-dimensional models) and the excised tumor in mean resection time(6:58 vs 8:22 min,p=0.162）and volumes excised（38.50 vs41.79mm³，p=0.976. Only 1/10 patients had positive surgical margins. The authors concluded that pre-surgical rehearsal could significantly im-prove resection strategy, but this study lacks a control group. Another feasibility study investigating how 3D(three-dimensional) printed kidney models can influence surgical procedures was performed by Maddox et al.[12].With the aim of allowing pre-operative and robotic surgical simulation, authors constructed patient-specific physical 3DMs(Three-dimensional models) made with materials that could approximate quite well the properties of renal tissue. Seven models were successfully created, and PN and herniorrhaphy were performed on each replica. After simulation, all patients underwent RAPN with negative surgical margins, reporting an average warm ischemia time of25 min. The mean R.E.N.A.L. nephropathy score was 7.4. Comparing the seven cases and the"Tulane Urology prospectively maintained RAPN database, "surgeries with 3DMs(Three-dimensional models) had larger tumors, fewer complications, longer warm ischemic time, fewer positive margins, and shorter hospitalization, but the only statistically significant finding was a decreased estimated blood loss(EBL)(185.7 vs.235.6 ml, p=0.01), suggesting that preoperative 3DM(Three-dimensional models) rehearsal may decrease the learning curve for trainees and improve surgical outcomes. Otherwise, the authors admitted that further evaluation was needed.
Kyung et al. compared 17 patients who underwent PN aided by prior consultation of 3D(three-dimensional) patient-specific kidney models with a control group consisting of patients who underwent PN from the same surgeon and approximately during the same time period (2014-2015)[13]. Similar to Maddox, the authors found that the only statistically significant difference was diminished intra-operative blood loss(IBL)(182cc vs.310cc, p<0.01). No complications occurred in the 3D printed group. Moreover, patients reported an overall improved understanding of the disease, surgical procedure, and trust in the surgical team after consultation of the 3DM(Three-dimensional models).
Despite the relatively small cohort, the frequent lack of a control group, and the low statistical power, these studies have contributed to support the efficacy of 3DM(Three-dimensional models) simulation before complex renal surgery.
Treatment for kidney disease: Cistanche herb & cistanche extract
Recently, Fan et al.retrospectively analyzed data of 69 patients who underwent 3D(three-dimensional) laparoscopic PN (LPN) and 58 who underwent traditional LPN between January 2016 and February 2018[14]. They reported a significant reduction in warm ischemia time(WIT) in the3D(three-dimensional) group (24.1±5.1 for the 3Dcohort and26.6±4.2min in the traditional LPN,p<0.05), against a longer surgery waiting time(13.6±3.4 days and 7.0 ±0.6 days, respectively,p<0.05). Subgroup analysis according to R.E.N.A.L.scores confirmed that, in patients with scores≥8, the 3D(three-dimensional) group had significantly shorter WIT and less IBL(131.9±78.5vs 179.2±76.1,p<0.05)than the traditional LPN group.
Finally, a Japanese group reported their preliminary experience of what they called"4D surgical navigation" in minimally invasive off-clamp PN [15]. It consists of a full-scale size 3D(three-dimensional) printed kidney designed so that the tumor and its margin(2-5 mm around the tumor) could be removed. This feature allowed the surgeon to visualize, during surgical planning, both pre-and post-resection kidneys (the fourth considered dimension was the time). Models helped the surgeons to create a working mental map for resection. Ten patients with complex renal masses(R.E.N.A.L.score≥8)were selected and underwent minimally invasive off-clamp PN with acceptable perioperative outcomes and surgical margins that resulted to be nearly identical to 3D(three-dimensional) printed tumors. A statistically significant difference was found in the time of intraoperative ultrasound with a 3D(three-dimensional) model compared to standard surgeries (mean 3.3 min vs6.3 min, respectively, p=0.021.Moreover, surgeons claimed the usefulness of 3DM(Three-dimensional models) tactile feedback. In contrast,4 to 9h were needed for printing and 3 to 9 days to complete the model. Costs of the models ranged from 450 to 680 dollars.
Treatment for kidney disease: Cistanche herb & cistanche extract
Applications of 3DP(Three-dimensional printing) in Percutaneous Nephrolithotomy (PCNL)
Nephrolithiasis is a common disease, and recent data show a prevalence up to 15% and an overall incidence rate growing [16]. Among endourologic techniques, percutaneous nephrolithotomy (PCNL)represents the gold standard for renal stones larger than 20 mm due to advantages in operative time and morbidity rates [17]. Renal access isn't always performed by urologists due to a not so easy learning curve. In fact, many studies have focused on imaging modalities used for guidance during percutaneous access for both urologists and radiologists. Anyhow, optimal selection of calyx for puncture and nephrostomy tract is one of the most important steps of PCNL surgical planning. Difficulties include performing a trajectory that leads directly to the target stone without affecting neighbor structures. Inadvertent organ injuries as well as multiple tracts before achieving the correct calyx access can lead to an increase in surgery duration, higher complications rates, and consequently to a longer postoperative length of stay (LOS)[18]. In recent years, the rapid development of patient-specific 3D(three-dimensional) segmentation and reconstruction in Urology has led to the combination of patient-specific 3DMs(Three-dimensional models) with preoperative planning for needle guidance during PCNL procedures. In 2015, Gadzhiev et al.proposed a plasticine 3D replica of the pelvicalyceal system on 32 patients with staghorn stones taken to the operating room and used as a reference model [19]. Percutaneous renal access was performed successfully in all cases; more than half(56%)had a single track with an overall stone-free rate (SFR) after a second look of 87.3%.
In 2019, Xu et al.printed 36 patient-specific 3DMs(Three-dimensional models)(3 for each patient) and simulated 3 puncture sites from upper, middle- and lower-pole calyces [20]. The puncture site that achieved the better SFR in the model was then used as a reference during surgery, and a good correspondence was found between the post-operative stone volume of the model and of the patient (p<0.001,95% CD).In late 2019, an Italian group presented a clinical case of a 30-year-old man with a left renal stone (25×15 mm)[21]. A 3D(three-dimensional) digital and physical renal model to aid the surgeon during the procedure in planning and guiding the percutaneous access during PCNL was performed. The patient safely underwent PCNL with 1 single percutaneous puncture(time of puncture 2 min). Overall surgical time was 90 min. A post-operative CT scan confirmed the patient's SFR. Brehmer et al.evaluated how 3D-CT reconstructions could influence the choice of access route and treatment outcomes in 35 patients planned for PCNL(88% with complex renal stone)[22]. Access routes were planned on 3D(three-dimensional)-CT reconstructions using anatomical landmarks(ribs, spinous process, etc.). The results were a change of access plan in 15/28 patients, while in 7 patients, access could not be planned without 3D-CT, totaling 22/35(63%). Sixty-nine percent of these patients (24/35)were stone-free after a single PCNL.
Similarly, Li et al. performed image segmentation and 3D(three-dimensional) reconstruction from CT scan of 15 patients with complex renal stone, including one patient with a horseshoe kidney,8 patients with partial/complete staghorn stones,and6 patients with multiple renal stones [23]. Virtual safe and reliable percutaneous renal access routes were established for each patient by comprehensive planning based on the 3DM (Three-dimensional models) of renal stones. The safest and most effective percutaneous tract for stone clearance was planned on the models and then uploaded onto a screen during the procedure in the operating room. The surgeon could visualize the reconstructed 3DM(Three-dimensional models) adjusting kidney transparency and felt more confident and comfortable with the access aided by the virtual puncture. During lithotripsy, the 3D(three-dimensional) models offered a panoramic view of the stone and collecting system guiding intraoperative nephroscopy. PCNL was completed successfully in all 15 patients, the one-session SFR was 93.3 %, and the final SFR was 100%.
Future studies are required, with larger cohorts, but Manning's hypothesis of "practice before you play" could become the standard of care for complex surgeries [24].
Treatment for kidney disease: Cistanche herb & cistanche extract
