A new model with an anatomically accurate human renal collecting system for training in fluoroscopy-guided percutaneous nephrolithotomy access

The value of 3D printing model combined PCNL in kidney stones: a systematic review and meta-analysis

INTRODUCTION

With the continuous advancement of medical imaging, 3D printing technology is emerging. This technology allows for the representation of complex objects in a model form. This research aims to delve into the irreplaceable value of percutaneous nephrolithotomy (PCNL) in conjunction with 3D printed models in urinary stone surgery. This forward-looking approach provides doctors with a new perspective, enabling them to plan and execute surgeries with greater precision, ultimately delivering a safer and more efficient treatment experience for patients. We evaluated the literature on PCNL for the kidney stones with the introduction of 3D printing models and conducted a meta-analysis. The assessed parameters included stone clearance rate, operation time, hospital stay, blood loss, puncture accuracy, and the rate of complications.

EVIDENCE ACQUISITION

We systematically searched the EMBASE, PubMed, Cochrane Library, SCIE, and Chinese Biomedical Literature Search databases for articles related to PCNL (Percutaneous Nephrolithotomy) with 3D printing models from January 2000 to January 2023. Data were managed and screened using Excel . Meta-analysis was performed for operation time, stone clearance rate, blood loss, puncture accuracy, length of hospital stay, and complications in PCNL combined with 3D printing model for kidney stone treatment. The quality of included articles was assessed using the risk of bias tool by the Cochrane Collaboration. Sensitivity analysis was conducted to assess the reliability of the results. Data were recorded using StataSE 17 software, and publication bias was examined using Egger's linear regression test.

EVIDENCE SYNTHESIS

We followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to conduct a systematic search and screening of literature relevant to the use of 3D printed models in the treatment of kidney stones. We conducted an extensive literature search across several major academic databases, including EMBASE, PubMed, Cochrane Library, SCIE, and Chinese Biomedical Literature Search databases, to ensure comprehensive coverage of relevant studies. Following the PRISMA process of screening and analysis, we ultimately included 10 randomized controlled trials with a combined sample of 608 for systematic review.

CONCLUSIONS

Across these studies, we identified the introduction of 3D printing models prior to surgery for kidney stones resulted in significant advantages for the experimental group compared to the control group in terms of operation time, stone clearance rates, puncture accuracy, hospital stay, blood loss, and the incidence of complications, providing valuable insights for further research and clinical practice.

A new training model using the self-healing properties of supramolecular hydrogels for endoscopic combined intrarenal surgery

The combination of hydronephrosis formation, ureteroscopic imaging, and ultrasound delineation has not been included in any non-biological training model of percutaneous nephrolithotomy or endoscopic combined intrarenal surgery. We aimed to develop a realistic kidney phantom using the self-healing properties of supramolecular hydrogels for percutaneous nephrolithotomy and endoscopic combined intrarenal surgery and evaluate its suitability as a training model.Expert and resident urologists performed ultrasound-guided renal pelvic punctures and flexible ureteroscopies for endoscopic combined intrarenal surgery using a training model. Subsequently, the training model was evaluated using a 17-item Likert scale questionnaire (range, 1-5 points). After being filled with carrageenan, the collecting system was inflated, and the relationship between the collecting system volume and collecting system pressure was determined. The durability of the model was verified by repeatedly inserting a 16-Fr access sheath. Five novices and seven urology experts performed the procedure. The mean questionnaire score was 4.25 (standard deviation, 0.37). The model was able to hold 50 mL of air, and the pressure in the collecting system ranged from 6 to 33 mmHg. Repeated punctures were possible even when a 16-Fr access sheath was inserted. Our new training model included the self-healing properties of supramolecular hydrogels, which are tough and flexible and can be evaluated using ultrasonography. According to the questionnaire score, the model was highly satisfactory and has potential as a new educational tool.

Three-Dimensional Printing and Bioprinting in Renal Transplantation and Regenerative Medicine: Current Perspectives

For patients with end-stage kidney disease (ESKD), renal transplantation is the treatment of choice, constituting the most common solid organ transplantation. This study aims to provide a comprehensive review regarding the application of three-dimensional (3D) printing and bioprinting in renal transplantation and regenerative medicine. Specifically, we present studies where 3D-printed models were used in the training of surgeons through renal transplantation simulations, in patient education where patients acquire a higher understanding of their disease and the proposed operation, in the preoperative planning to facilitate decision-making, and in fabricating customized, tools and devices. Three-dimensional-printed models could transform how surgeons train by providing surgical rehearsal platforms across all surgical specialties, enabling training with tissue realism and anatomic precision. The use of 3D-printed models in renal transplantations has shown a positive impact on surgical outcomes, including the duration of the operation and the intraoperative blood loss. Regarding 3D bioprinting, the technique has shown promising results, especially in the field of microfluidic devices, with the development of tissue demonstrating proximal tubules, glomerulus, and tubuloinerstitium function, and in renal organoid development. Such models can be applied for renal disease modeling, drug development, and renal regenerative medicine.

Classification and clinical significance of the posterior group of renal calyces

To study the anatomical orientation of the posterior group of calyces based on reconstructed images of computerized tomography urography (CTU) and provide a novel classification with its clinical significance. Clinical data of a total of 1321 patients, who underwent CTU examination in our hospital were retrospectively analyzed. Among these, a total of 2642 3-dimensional reconstructed images of CTU scans were considered in this study. Based on the morphology of the renal calyces and the influence on the establishment of surgical access, the posterior group renal calyces are classified into 3 major types including pot-belly type, classically branched and elongated branched. The classically branched type is further classified into 3 sub-types: a, b and c, based on the association of minor calyces of the posterior group to the major calyces. Type a is derived from 1 group of major calyces only, type b is derived from 2 groups of major calyces simultaneously, and type c is derived from 3 groups of major calyces simultaneously. Statistical findings revealed that all kidneys possess posterior group calyces. The percentage of occurrence of pot-belly type, classically branched and elongated branched is 8.06%, 73.13%, and 18.81%, respectively. The anatomical typing of the classical branching type occurred in 19.36%, 68.17%, and 12.47% for types a, b, and c, respectively. In this study, the posterior group calyces were found to be present across all patients. The posterior group calyces were highest in the classical branching type, of which anatomical typing was highest in type b. The typing of the posterior group of calyces could provide an anatomical basis for percutaneous nephrolithotomy (PCNL) puncture from the posterior group.

Additive Manufacturing of 3D Anatomical Models-Review of Processes, Materials and Applications

The methods of additive manufacturing of anatomical models are widely used in medical practice, including physician support, education and planning of treatment procedures. The aim of the review was to identify the area of additive manufacturing and the application of anatomical models, imitating both soft and hard tissue. The paper outlines the most commonly used methodologies, from medical imaging to obtaining a functional physical model. The materials used to imitate specific organs and tissues, and the related technologies used to produce, them are included. The study covers publications in English, published by the end of 2022 and included in the Scopus. The obtained results emphasise the growing popularity of the issue, especially in the areas related to the attempt to imitate soft tissues with the use of low-cost 3D printing and plastic casting techniques.

Role of three dimensional (3D) printing in endourology: An update from EAU young academic urologists (YAU) urolithiasis and endourology working group

The management of nephrolithiasis has been complemented well by modern technological advancements like virtual reality, three-dimensional (3D) printing etc. In this review, we discuss the applications of 3D printing in treating stone disease using percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS). PCNL surgeries, when preceded by a training phase using a 3D printed model, aid surgeons to choose the proper course of action, which results in better procedural outcomes. The 3D printed models have also been extensively used to train junior residents and novice surgeons to improve their proficiency in the procedure. Such novel measures include different approaches employed to 3D print a model, from 3D printing the entire pelvicalyceal system with the surrounding tissues to 3D printing simple surgical guides.

Effect of a three-dimensional (3D) printed kidney model on patient understanding of the percutaneous nephrolithotomy procedure: a preliminary study

Three-dimensional (3D) printed anatomical models can provide cognitive anatomical information. We aimed to study the effect of a 3D printed kidney model on patient understanding of kidney anatomy and the percutaneous nephrolithotomy (PCNL) procedure as well as the overall patient satisfaction with the model. Seven patients who underwent PCNL were enrolled in the study. Personalized 3D printed kidney models were constructed based on the patients' computed tomography images. Patients completed two questionnaires regarding their understanding and satisfaction with the use of the 3D printed kidney model before and after using the model during informed consent. The mean age of the study population was 58.0 years. Comparison of patient understanding and satisfaction between the two questionnaires showed a general trend toward better understanding and improved satisfaction with use of 3D printed kidney models. Statistically significant results were seen for understanding of kidney anatomy, stone size, procedure, and satisfaction (p values 0.046, 0.025, 0.046, and 0.046, respectively). Five of the seven patients (71.4%) answered that the model was very useful. However, none of the patients answered that the cost was appropriate. In the current study, patients showed improved understanding of the kidney anatomy and the PCNL procedure and higher satisfaction with using the 3D printed kidney model during informed consent. With further studies using larger patient numbers and decreased production cost, using 3D printed kidney models has the potential to be a useful adjunct for patient understanding during PCNL.

Development and Validation of a Novel Skills Training Model for PCNL, an ESUT project

BACKGROUND AND AIM

The aim of this study is to validate a totally non biologic training model that combines the use of ultrasound and X ray to train Urologists and Residents in Urology in PerCutaneous NephroLithotripsy (PCNL).

METHODS

The training pathway was divided into three modules: Module 1, related to the acquisition of basic UltraSound (US) skill on the kidney; Module 2, consisting of correct Nephrostomy placement; and Module 3, in which a complete PCNL was performed on the model. Trainees practiced on the model first on Module 1, than in 2 and in 3. The pathway was repeated at least three times. Afterward, they rated the performance of the model and the improvement gained using a global rating score questionnaire.

RESULTS

A total of 150 Urologists took part in this study. Questionnaire outcomes on this training model showed a mean 4.21 (range 1-5) of positive outcome overall. Individual constructive validity showed statistical significance between the first and the last time that trainees practiced on the PCNL model among the three different modules. Statistical significance was also found between residents, fellows and experts scores. Trainees increased their skills during the training modules.

CONCLUSION

This PCNL training model allows for the acquisition of technical knowledge and skills as US basic skill, Nephrostomy placement and entire PCNL procedure. Its structured use could allow a better and safer training pathway to increase the skill in performing a PCNL.

Fabrication of low-cost realistic three-dimensional static kidney phantom for ultrasound-guided biopsy applications

Background:

The rapid growth of using ultrasound-guided interventional procedures, including biopsy and drainage, which considered painful procedures, leads to improving the practice cycle of ultrasound-guided procedures. Fabrication of low-cost tissue-mimicking phantoms that serve as a training tool medium for kidney needle biopsy procedures has dramatically overcome the drawbacks associated with these practices, such as reducing the number of miss lesions, medical errors, and recurrence rate as well as these phantoms are widely available and considered a good substitute for cadavers which were not always available and relativity expensive. However, several drawbacks are associated with current kidney phantom models, mainly the short shelf life and the high fabrication cost.

Methods:

This study aims to fabricate a realistic three-dimensional static mature human kidney phantom from low cost and available material for training on ultrasound-guided interventional procedures mainly biopsy test; the material used to fabricate our model is the gelatin-agar mixture.

Results:

This model proved that it is a tissue-mimicking material by measuring their acoustic properties which nearly the same as real human kidney tissue.

Conclusion:

The results of practicing interventional procedures on our phantom model showed good and easy uses for interventional procedures training as well as make it a preferable and economically affordable model.

A new model of inexpensive portable homemade PERC Mentor (IPHOM) and its validation

Background

Percutaneous nephrolithotomy (PCNL) is a complex surgery and has a flat learning curve. Due to this and the ethical issues, trainees do not get enough hands on exposure. Virtual simulator is very expensive and bulky. Animal model requires legal clearance. This inexpensive portable homemade PERC Mentor (IPHOM) teaches all the major aspects of PCNL surgery. This article has shown the way to make this model and its validation study.

Methods

IPHOM can be made at home with carton box, ball bearings, LED torch and some hospital wastes. After a short demonstration of IPHOM, 14 residents and 4 urologists were given 8 tasks to perform on it followed by 15-min supervised practice exercise on day 0 and day 1. Their performance was reassessed on day 2 and 3. Response to 17 feedback points was recorded on a seven-point Likert scale.

Results

There was significant difference between the performance of expert and novice on day 0. Expert completed all the tasks in less time and no. of attempts. The time for tract dilatation and duration of radiation exposure were significantly less in the expert group. The performance of both expert and novice improved on day 2 and 3, but the improvement was significantly more in novice. Response to the feedback points showed no difference between expert and novice (p > .05).

Conclusions

We have found that training on IPHOM has improved the concept and skills of PCNL in residents. The simplicity and low cost of the model make it constructible at home.

A review of simulation training and new 3D computer-generated synthetic organs for robotic surgery education

We conducted a comprehensive review of surgical simulation models used in robotic surgery education. We present an assessment of the validity and cost-effectiveness of virtual and augmented reality simulation, animal, cadaver and synthetic organ models. Face, content, construct, concurrent and predictive validity criteria were applied to each simulation model. There are six major commercial simulation machines available for robot-assisted surgery. The validity of virtual reality (VR) simulation curricula for psychomotor assessment and skill acquisition for the early phase of robotic surgery training has been demonstrated. The widespread adoption of VR simulation has been limited by the high cost of these machines. Live animal and cadavers have been the accepted standard for robotic surgical simulation since it began in the early 2000s. Our review found that there is a lack of evidence in the literature to support the use of animal and cadaver for robotic surgery training. The effectiveness of these models as a training tool is limited by logistical, ethical, financial and infection control issues. The latest evolution in synthetic organ model training for robotic surgery has been driven by new 3D-printing technology. Validated and cost-effective high-fidelity procedural models exist for robotic surgery training in urology. The development of synthetic models for the other specialties is not as mature. Expansion into multiple surgical disciplines and the widespread adoption of synthetic organ models for robotic simulation training will require the ability to engineer scalability for mass production. This would enable a transition in robotic surgical education where digital and synthetic organ models could be used in place of live animals and cadaver training to achieve robotic surgery competency.

New Technologies for Kidney Surgery Planning 3D, Impression, Augmented Reality 3D, Reconstruction: Current Realities and Expectations

Purpose of review

We aim to summarize the current state of art about 3D applications in urology focusing on kidney surgeries. In addition we aim to provide a snapshot about future perspective of intraoperative applications of augmented reality (AR).

Recent findings

A variety of applications in different fields have been proposed. Many applications concern current realities and 3D reconstruction, while some others are about future perspective. The majority of recent studies have focused their attention on preoperative surgical planning, patient education, surgical training, and AR.

Summary

The disposability of 3D models in healthcare scenarios might improve surgical outcomes, learning curves of novice surgeons and residents, as well as patients’ understanding and compliance, allowing a more shared surgical decision-making.

Three-dimensionally printed non-biological simulator for percutaneous nephrolithotomy training

Objective: We sought to improve the educational and pre-operative training on various stages of percutaneous nephrolithotomy (PCNL) under fluoroscopic and ultrasound guidance. We developed a three-dimensional (3D) printed simulator (3D-printed PCNL model) for urological trainees.Methods: 40 s year urology residents were randomly assigned into two groups, completing PCNL surgical steps on a URO Mentor™ surgical simulator (Group A) or on our new 3D-printed PCNL model (Group B). Following the training, both groups completed a standardized questionnaire (Likert scale from 0 to 10) which we used to asses the learning curve associated with PCNL training.Results: The mean score of Group A was 65.2/80 while Group B was 76.1/80. Mann-Whitney U-test showed no significant difference between the groups (U = 16, p < 0.05).Conclusion: The 3D-printed PCNL model developed is a novel and highly effective tool that can facilitate enhanced endourological education and personalized pre-operative planning for urolithiasis cases. According to the criteria tested, residents who used our 3D-printed PCNL models performed better under all metrics.

Developing Neuraxial and Regional Pain Procedural Skills Through Innovative 3-Dimensional Printing Technology

Context

Various forms of simulation-based training, including training models, increase training opportunities and help assess performance of a task. However, commercial training models for lumbar puncture and epidural procedures are costly.

Objective

To assess medical students’ and residents’ perception of 3-dimensional (3D)-printed lumbar, cervical, and pelvic models for mastering joint injection techniques and to determine the utility of ultrasonography-guided needle procedure training.

Methods

Osteopathic medical students and residents used in-house 3D-printed gel joint models during an injection ultrasonography laboratory for mastering lumbar epidural, caudal epidural, sacroiliac, and facet joint injection techniques. After the laboratory, they answered a 17-item survey about their perception of the importance of the models in medical education and future practice. The survey also evaluated comfort levels with performing joint injections after using the models, overall satisfaction with the models, and likelihood of using models in the future.

Results

Thirty-six medical students and residents participated. Both students and residents agreed that 3D-printed models were easy to use, aided understanding of corresponding procedures, and increased comfort with performing joint injections (all P<.001). Most participants (35 [97.2%]) believed that the models were reasonable alternatives to commercial models. Over half felt capable of successfully performing cervical or pelvic (22 [61.1%]) and lumbar epidural (23 [63.9%]) injections. The majority of participants (34 [94.4%]) would like to use the models in the future for personal training purposes. Overall, 100% believed that the 3D-printed models were a useful tool for injection training.

Conclusions

Results suggest that 3D-printed models provided realistic training experience for injection procedures and seemed to allow participants to quickly master new injection techniques. These models offer a visual representation of human anatomy and could be a cost-saving alternative to commercial trainers.

Personalized Renal Collecting System Mockup for Procedural Training Under Ultrasound Guidance

Objective: In recent years, there has been increasing interest in the use of ultrasound guidance for endoscopic and percutaneous procedures. Kidney mockups could be used for training, however, available mockups are normally incompatible with ultrasound imaging. We developed a reproducible method to manufacture an ultrasound-compatible collecting system mockup that can be made at urology laboratories. Methods: Positive and negative molding methods were used. A three-dimensional (3D) digital model of a urinary collecting system and the overlying skin surface were segmented from computed tomography. A containment mold (negative) was made following the shape of the skin surface using 3D printing. A collecting system mold (positive) was also 3D printed, but made of a dissolvable material. The containment mold was filled with a gelatin formula with the collecting system mold submersed in situ within. After the gelatin solidified, a solution was used to dissolve the collecting system mold, but not the gelatin, leaving a cavity with the shape of the collecting system. The gelatin was extracted from the container mockup and the collecting system cavity was filled with water. The mockup was imaged with ultrasound to assess echogenicity and suitability for simulating ultrasound-guided procedures. Results: A clear shape corresponding to the collecting system was observed inside the gel structure. Structural integrity was maintained with no observable manufacturing marks or separation seams. Ultrasound images of the mockup demonstrated clear differentiation at the gelatin/water interface. A mock stone was placed in the collecting system and needle targeted to simulate percutaneous needle access. Conclusion: We developed a simple method to manufacture a personalized mockup of the renal collecting system of a patient that can be used for ultrasound-guided percutaneous needle access. Generic collecting system mockups can be used for training, and patient-specific models can be used to simulate and decide the best access path before a clinical case.

A novel biological model for training in percutaneous renal access

Objective: To develop a new model comprised of a bovine kidney within a chicken carcass for training in percutaneous renal access (PRA) and compare its effectiveness with the traditional mannequin model.

Subjects, materials and methods: The study was conducted from January 2017 to June 2017. The content and the construct validity of the new model were confirmed after which it was compared with the traditional non-biological model for PRA. In all, 20 urology residents, with experience of <20 cases, were enrolled in the study. The parameters assessed were time to puncture, attempts to successful puncture, and fluoroscopy exposure time. They were also asked to complete a subjective assessment questionnaire.

Results: The new ex vivo biological model had both content and construct validity. On comparison with the non-biological model, there was no statistically significant difference between the two models for time to puncture, total fluoroscopy exposure, and also the number of attempts taken for a successful puncture. The participants felt that the new biological model was better than the non-biological model in terms of overall assessment, tissue feel, and confidence in training. But the non-biological model scored better than the new biological model for ease of puncture and model preparation.

Conclusion: The present model is inexpensive and easy to construct, and has both content and construct validity. It is a feasible model for fluoroscopy-guided PRA.

Abbreviations: 3D: three-dimensional; PCNL: percutaneous nephrolithotomy; PRA: percutaneous renal access; VR: virtual reality

3D printing technology and its role in urological training

PURPOSE

Surgical simulation and 3D printing have both been gaining traction exclusively over the past decade, and now have started to appear simultaneously in current research. The opinion that surgical simulation should be part of surgery curricula is becoming ever more apparent. In this review, we highlight and briefly examine the 3D printing workflow, and each facet of the current body of literature using this technology in the augmentation of surgical training, in addition to the challenges currently faced.

METHODS

A broad literature search was conducted pertaining to the utilisation of 3D printing in urology, aiming to sample the majority of use-cases of this fairly novel technology. The 3D printing workflow, current use-cases of 3D printing as applied to urological training, and challenges faced have been described.

RESULTS

A respectable number of surgical use-cases utilising 3D printing technology in their development were identified, including but not limited to percutaneous nephrolithotomy, partial nephrectomy, renal transplantation, laparoscopic pyeloplasty, prostate brachytherapy, transurethral resection of bladder tumours, urethrovesical anastomosis simulation devices, in addition to laparoscopic trainers and robotic surgery phantoms.

CONCLUSION

Over the last decade, urology has taken this cutting-edge technology in its stride; flaunting its efficacy in the augmentation of a number of procedural training applications. The number of use cases for this technology is only expected to rise as its virtues are demonstrated, the ease of use and availability of 3D printing units advances, and costs abated.

A High-Fidelity Phantom for the Simulation and Quantitative Evaluation of Transurethral Resection of the Prostate

Transurethral resection of the prostate (TURP) is a minimally invasive endoscopic procedure that requires experience and skill of the surgeon. To permit surgical training under realistic conditions we report a novel phantom of the human prostate that can be resected with TURP. The phantom mirrors the anatomy and haptic properties of the gland and permits quantitative evaluation of important surgical performance indicators. Mixtures of soft materials are engineered to mimic the physical properties of the human tissue, including the mechanical strength, the electrical and thermal conductivity, and the appearance under an endoscope. Electrocautery resection of the phantom closely resembles the procedure on human tissue. Ultrasound contrast agent was applied to the central zone, which was not detectable by the surgeon during the surgery but showed high contrast when imaged after the surgery, to serve as a label for the quantitative evaluation of the surgery. Quantitative criteria for performance assessment are established and evaluated by automated image analysis. We present the workflow of a surgical simulation on a prostate phantom followed by quantitative evaluation of the surgical performance. Surgery on the phantom is useful for medical training, and enables the development and testing of endoscopic and minimally invasive surgical instruments.

Anterior Lumbar Interbody Fusion Using a Personalized Approach: Is Custom the Future of Implants for Anterior Lumbar Interbody Fusion Surgery?

BACKGROUND

Spine surgery has the potential to benefit from the use of three-dimensional (3D) printing technology (additive manufacturing), particularly in cases of complex anatomic diseases. Custom devices have the potential to reduce operative times, reduce blood loss, provide immediate stability, and improve fusion rates.

CASE DESCRIPTION

A 34-year-old man presented with 3-year history of bilateral L5 radiculopathy caused by bilateral L5 pars defect, L5/S1 degenerative disc disease, and severe foraminal stenosis. Anterior lumbar interbody fusion surgery was determined to be the most efficacious method for distraction of the disc space to increase the foraminal volume and stabilization of the motion segment. Surgical decompression and reconstruction was performed in combination with a 3D printed custom interbody implant. Custom design features included corrective angulation to restore lumbar lordosis, preplanned screw holes in the 3D implant, and device end plate interface geometry designed to shape-match with the patient's end plate anatomy.

CONCLUSIONS

The use of patient-specific implants has reduced operative time significantly, which may offset costs of increased time spent preplanning the procedure. Surgical procedures can be preplanned using 3D models reconstructed from patient computed tomography and/or magnetic resonance imaging scans. Planning can be aided by 3D printed models of patient anatomy, which surgeons can use in training before performing complex procedures. When considering implants and prostheses, the use of 3D printing allows a superior anatomic fit for the patient compared with generic devices, with the potential to improve restoration of nonpathologic anatomy.

A realistic, durable, and low-cost training model for percutaneous renal access using ballistic gelatin

OBJECTIVE

The purpose of this study was to design and implement a realistic, durable, and low-cost training model for percutaneous renal access.

MATERIAL AND METHODS

Ballistic gelatin mixed with radiographic contrast was poured into surgical gloves to create a radio-dense renal collecting system. The collecting system model was then embedded in a pure ballistic gelatin block resting upon a clear acrylic glass base. Finally, the model was covered by a visually opaque polyurethane foam cover with chalk sticks positioned to simulate ribs. Experienced attending urologists and interventional radiologists, urology residents, and medical students used the model to access the upper, middle, and lower renal calyces under fluoroscopic guidance. Outcomes included model durability, realism rated by participants on a visual analogue scale, and cost.

RESULTS

The ballistic gelatin model was durable and anatomically realistic. Each model sustained over 200 needle punctures with no significant compromise in structural integrity or any contrast leakage. Attending and resident physicians considered it to provide an accurate simulation of renal access and medical students and residents considered the model to be a practical training modality (residents 8.4/10 vs. medical students 9.4/10). The total cost for one model was $60.

CONCLUSION

The ballistic gelatin collecting system provided a realistic, durable, and low-cost renal access training model. This could allow trainees to develop skills without compromising patient safety.

Introduction of an ex-vivo pig model for teaching percutaneous nephrolithotomy access techniques

INTRODUCTION

In North America, obtaining access for percutaneous nephrolithotomy (PCNL) is not often performed by urologists. Hands-on training sessions help to ensure this skill continues within the urological community. An ex-vivo pig kidney model was developed for simulation. This model uses porcine tissues with a fluoroscopic C-arm and standard PCNL equipment. The bullseye or triangulation techniques are both possible. We propose this as a high-fidelity tool for teaching PCNL access.

METHODS

The pig kidney, fat, ribs, flank, and skin were arranged anatomically on a table with fluoroscopy. Hands-on training was provided to residents and urologists using the ex-vivo pig model and a silicone-based percutaneous access model. Questionnaires were given at the end of the session.

RESULTS

There was a total 14 responders for each model, with incomplete responses on two surveys. A total of 15% of responders for the pig model and 7% of responders for the silicone model had previous percutaneous access experience. For the pig model, 93% of trainees agreed or strongly agreed that the model was easy to use, and 79% of the silicone model trainees felt the same. After the session, 50% of silicone model trainees and 86% of pig model trainees reported increased confidence in their ability to obtain PCNL access. All the pig model trainees and 71% of the silicone model trainees felt that the simulation activity was worthwhile.

CONCLUSIONS

The inexpensive but anatomically realistic ex-vivo pig model using real-world equipment provides trainees with an excellent tool to learn PCNL access.

3D printing of surgical hernia meshes impregnated with contrast agents: in vitro proof of concept with imaging characteristics on computed tomography

BACKGROUND

Selected medical implants and other 3D printed constructs could potentially benefit from the ability to incorporate contrast agents into their structure. The purpose of the present study is to create 3D printed surgical meshes impregnated with iodinated, gadolinium, and barium contrast agents and characterize their computed tomography (CT) imaging characteristics. Commercial fused deposition layering 3D printing was used to construct surgical meshes impregnated with imaging contrast agents in an in vitro model. Polycaprolactone (PCL) meshes were printed containing iodinated, gadolinium, or barium contrast; control PCL meshes without contrast were also fabricated. The three different contrast agents were mixed with PCL powder and directly loaded into the 3D printer. CT images of the three contrast-containing meshes and the control meshes were acquired and analyzed using small elliptical regions of interest to record the Hounsfield units (HU) of each mesh. Subsequently, to test their solubility and sustainability, the contrast-containing meshes were placed in a 37 °C agar solution for 7 days and imaged by CT at days 1, 3 and 7.

RESULTS

All 3D printed meshes were visible on CT. Iodinated contrast meshes had the highest attenuation (2528 mean HU), significantly higher than both and gadolinium (1178 mean HU) and barium (592 mean HU) containing meshes. Only barium meshes sustained their visibility in the agar solution; the iodine and gadolinium meshes were poorly perceptible and had significantly lower mean HU compared to their pre-agar solution imaging, with iodine and gadolinium present in the adjacent agar at day 7 CT.

CONCLUSION

3D prints embedded with contrast materials through this method displayed excellent visibility on CT; however, only barium mesh maintained visibility after 7 days incubation on agar at human body temperature. This method of 3D printing with barium may have potential applications in a variety of highly personalized and CT visible medical devices.

The Anatomic Structure of a Fused Renal Pyramid and Its Clinical Significance in the Establishment of Percutaneous Renal Access

OBJECTIVE

To explore the clinical significance of the fused renal pyramid (FRP) in establishing percutaneous renal access, and the anatomic basis for avoiding vascular injury caused by puncturing through this renal pyramid with the aim of achieving accurate puncture in percutaneous nephrolithotomy.

MATERIALS AND METHODS

Sixty-two cadaveric kidneys and 105 porcine kidneys were selected for the assessment of regional anatomy, to explore the anatomic structure of the FRP and determine its frequency. Then, we compared the effects of 4 different puncture paths on the occurrence of renal vascular injury when respectively punctured through the normal renal pyramid (group A), the centerline of one side pyramid of the FRP (group B), the center of the entire FRP (group C) and the renal column (group D).

RESULTS

The incidence of FRP in human kidneys is not low. The artery in the kidney can be divided into 6 grades. The grade IV branch-interlobar artery courses through the FRP. There was significant difference in the degree of arterial injury between the group A and C (P = .003), while no significant difference between the group A and B (P = .151). There was significant difference in the proportion of interlolar artery injury between group A and C (P <.001), while no significant difference between group A and B (P = .239).

CONCLUSION

It is necessary to carefully identify and bypass the FRP when establishing a percutaneous renal access. If unavoidable, the puncture path should be on the centerline of one side pyramid of the FRP.

L5 En-Bloc Vertebrectomy with Customized Reconstructive Implant: Comparison of Patient-Specific Versus Off-the-Shelf Implant

BACKGROUND

Spine surgery has the potential to benefit from additive manufacturing/3-dimensional printing (3DP) technology with complex anatomical pathologies requiring reconstruction, with the potential to customize surgery to reduce operative times, reduce blood loss, provide immediate stability, and potentially improve fusion rates. We report a unique case of intraoperative trial placement of a custom patient-specific implant (PSI) versus the final implantation of a customizable off-the-shelf (OTS) implant. Data collected for comparison included time to implant, ease of implantation, firmness of press-fit, and fixation options after implantation.

CASE DESCRIPTION

A 64-year-old man presented with low back pain. Computed tomography and magnetic resonance imaging revealed a solitary lesion in the L5 vertebral body, confirmed by positron emission tomography scan. Removal of the L5 vertebral body was performed, and reconstruction was achieved with an expandable cage. The time of implant insertion was minimal with the PSI (90 seconds) versus the OTS (>40 minutes). Immediate press-fit and "firmness" of implantation was clearly superior with the PSI, although this was an intraoperative subjective assessment. Other benefits include integral fixation that is predetermined with the PSI, reduced time and blood loss, and ease of bone grafting with a PSI.

CONCLUSIONS

Use of 3DP has been able to reduce operative time significantly. Surgeons can train before performing complex procedures, which enhances their presurgical planning, with the goal to maximize patient outcomes. When considering implants and prostheses, the use of 3DP allows a superior anatomical fit for the patient, with the potential to improve restoration of anatomy.

From medical imaging data to 3D printed anatomical models

Anatomical models are important training and teaching tools in the clinical environment and are routinely used in medical imaging research. Advances in segmentation algorithms and increased availability of three-dimensional (3D) printers have made it possible to create cost-efficient patient-specific models without expert knowledge. We introduce a general workflow that can be used to convert volumetric medical imaging data (as generated by Computer Tomography (CT)) to 3D printed physical models. This process is broken up into three steps: image segmentation, mesh refinement and 3D printing. To lower the barrier to entry and provide the best options when aiming to 3D print an anatomical model from medical images, we provide an overview of relevant free and open-source image segmentation tools as well as 3D printing technologies. We demonstrate the utility of this streamlined workflow by creating models of ribs, liver, and lung using a Fused Deposition Modelling 3D printer.

Soft 3D-Printed Phantom of the Human Kidney with Collecting System

Organ models are used for planning and simulation of operations, developing new surgical instruments, and training purposes. There is a substantial demand for in vitro organ phantoms, especially in urological surgery. Animal models and existing simulator systems poorly mimic the detailed morphology and the physical properties of human organs. In this paper, we report a novel fabrication process to make a human kidney phantom with realistic anatomical structures and physical properties. The detailed anatomical structure was directly acquired from high resolution CT data sets of human cadaveric kidneys. The soft phantoms were constructed using a novel technique that combines 3D wax printing and polymer molding. Anatomical details and material properties of the phantoms were validated in detail by CT scan, ultrasound, and endoscopy. CT reconstruction, ultrasound examination, and endoscopy showed that the designed phantom mimics a real kidney’s detailed anatomy and correctly corresponds to the targeted human cadaver’s upper urinary tract. Soft materials with a tensile modulus of 0.8–1.5 MPa as well as biocompatible hydrogels were used to mimic human kidney tissues. We developed a method of constructing 3D organ models from medical imaging data using a 3D wax printing and molding process. This method is cost-effective means for obtaining a reproducible and robust model suitable for surgical simulation and training purposes.

Simulation for Percutaneous Renal Access: Where Are We?

OBJECTIVES

Percutaneous renal access (PCA) is a challenging step during percutaneous nephrolithotomy. The aim of this study is to review the literature for different types of simulators described for PCA.

METHODS

Databases of Medline, Embase, Cochrane Library, OvidSP, and Google Scholar were systematically searched until May 2016. The studies were analyzed regarding the type of simulator (nonbiologic, biologic, live animal, and virtual reality [VR]), type of validity (face, content, construct, and predictive), cost-effectiveness, and whether these simulators have been used for training and/or assessment of PCA. In addition, the study looked at the educational impact of these simulators in terms of the transfer of PCA skills to the operating room.

RESULTS

Several bench, animal, and VR simulators for training in PCA were identified. Only few studies were found on assessment of PCA skills. Biological bench models used porcine or bovine kidneys wrapped within foam, silicone, chicken carcass, or full-thickness skin flap alone. Other biological models used additional subcutaneous fascia, muscle, or ribs. Nonbiological models used prototypes, including 3D printing. Only one study reported the use of anesthetized live pig for training. The PERC Mentor™ was the only VR simulator, which has been validated for training and assessment of PCA skills. However, none of these studies assessed the educational impact of PCA simulators. Furthermore, most of the studies did not address the validity and the cost of the simulator.

CONCLUSIONS

While several biological and nonbiological PCA models exist, there is paucity of literature regarding the validity and educational impact of these simulators. The PERC Mentor simulator is the sole validated simulator for training and assessment of PCA skills. However, it is expensive and there is little evidence of its educational impact. Therefore, more research is needed to validate the available simulators and assess their educational impact for urology trainees.

Fabrication and assessment of 3D printed anatomical models of the lower limb for anatomical teaching and femoral vessel access training in medicine

For centuries, cadaveric dissection has been the touchstone of anatomy education. It offers a medical student intimate access to his or her first patient. In contrast to idealized artisan anatomical models, it presents the natural variation of anatomy in fine detail. However, a new teaching construct has appeared recently in which artificial cadavers are manufactured through three-dimensional (3D) printing of patient specific radiological data sets. In this article, a simple powder based printer is made more versatile to manufacture hard bones, silicone muscles and perfusable blood vessels. The approach involves blending modern approaches (3D printing) with more ancient ones (casting and lost-wax techniques). These anatomically accurate models can augment the approach to anatomy teaching from dissection to synthesis of 3D-printed parts held together with embedded rare earth magnets. Vascular simulation is possible through application of pumps and artificial blood. The resulting arteries and veins can be cannulated and imaged with Doppler ultrasound. In some respects, 3D-printed anatomy is superior to older teaching methods because the parts are cheap, scalable, they can cover the entire age span, they can be both dissected and reassembled and the data files can be printed anywhere in the world and mass produced. Anatomical diversity can be collated as a digital repository and reprinted rather than waiting for the rare variant to appear in the dissection room. It is predicted that 3D printing will revolutionize anatomy when poly-material printing is perfected in the early 21st century.

Three-dimensional printing in surgery: a review of current surgical applications

BACKGROUND

Three-dimensional printing (3DP) is gaining increasing recognition as a technique that will transform the landscape of surgical practice. It allows for the rapid conversion of anatomic images into physical objects, which are being used across a variety of surgical specialties. It has been unclear which groups are leading the way in coming up with novel ways of using the technology and what specifically the technology is being used for. The aim of this article was to review the current applications of 3DP in modern surgical practice.

MATERIALS AND METHODS

An electronic search was carried out in MEDLINE, EMBASE, and PsycINFO for terms related to 3DP. These were then screened for relevance and practical applications of the technology in surgery.

RESULTS

Four hundred eighty-eight articles were initially found, and these were eventually narrowed down to 93 full-text articles. It was determined that there were three main areas in which the technology is being used to print: (1) anatomic models, (2) surgical instruments, and (3) implants and prostheses.

CONCLUSIONS

Different specialties are at different stages in the use of the technology. The costs involved with implementing the technology and time taken for printing are important factors to consider before widespread use. For the foreseeable future, this is an exciting and interesting technology with the capacity to radically change health care and revolutionize modern surgery.

Percutaneous stone removal: new approaches to access and imaging

Percutaneous renal access and removal of large renal calculi was first described nearly 40 years ago and has since become the gold standard in management of large and complex renal calculi. In this same time period, technological and medical advances have allowed this procedure to develop in improved efficacy and morbidity. The following review offers an update to new approaches to percutaneous renal access and imaging in the management of large and complex renal calculi.

Sculpturing in urology, or how to make percutaneous nephrolithotomy easier

PURPOSE

To investigate the usefulness of Plasticine biomodeling in surgical percutaneous management of complex renal stone.

PATIENTS AND METHODS

A total of 32 patients with complex renal stones (complete staghorn stones or partial staghorn stone with multiple caliceal stones) were included in this study from 2012 to 2013. Computed tomography (CT) urography with three-dimensional (3D) reconstructions was used as standard preoperative imaging in all patients. Preoperatively, Plasticine replication of the pelvicaliceal system was performed by the operating surgeon, based on the gathered 3D reconstructions. Then the model was taken to the operating room and used as a reference model in a sterile polyethylene bag during the operation.

RESULTS

Percutaneous renal access was achieved successfully in all cases. Twenty-nine (91%) patients were treated in the prone position and only 3 (9%) in supine position. There were 18 (56%) patients who had a single tract, 9 (28%) patients had two tracts, 3 (9%) patients had three tracts, and one (3%) patient needed four tracts. The mean operative time was 92 (±26) minutes. Second-look percutaneous nephrolithotomy (PCNL) was needed in 9 of 32 (28%) patients. All second-look sessions were performed in 2 to 3 days and/or on a normalized temperature. Six of 11 (54.5%) patients with complete staghorn stones needed a second-look PCNL session. Complete stone clearance was confirmed by low-dose CT, performed at 24 hours after surgery, in 89.4% of the patients treated by a single PCNL session and 82% in those who needed second-look sessions. The overall stone-free rate (SFR) in the study after second looks was 87.3%.

CONCLUSIONS

The proposed Plasticine 3D model seems to provide better preoperative renal collecting system appreciation and to serve as a reference tool during the operation, which in turn might increase SFRs and lower the complications rate after PCNL.