Prediction of metabolic syndrome and its associated risk factors in patients with chronic kidney disease using machine learning techniques

INTRODUCTION

Chronic kidney disease (CKD) and metabolic syndrome (MS) are recognized as public health problems which are related to overweight and cardiometabolic factors. The aim of this study was to develop a model to predict MS in people with CKD.

METHODS

This was a prospective cross-sectional study of patients from a reference center in São Luís, MA, Brazil. The sample included adult volunteers classified according to the presence of mild or severe CKD. For MS tracking, the k-nearest neighbors (KNN) classifier algorithm was used with the following inputs: gender, smoking, neck circumference, and waist-to-hip ratio. Results were considered significant at p < 0.05.

RESULTS

A total of 196 adult patients were evaluated with a mean age of 44.73 years, 71.9% female, 69.4% overweight, and 12.24% with CKD. Of the latter, 45.8% had MS, the majority had up to 3 altered metabolic components, and the group with CKD showed statistical significance in: waist circumference, systolic blood pressure, diastolic blood pressure, and fasting blood glucose. The KNN algorithm proved to be a good predictor for MS screening with 79% accuracy and sensitivity and 80% specificity (area under the ROC curve - AUC = 0.79).

CONCLUSION

The KNN algorithm can be used as a low-cost screening method to evaluate the presence of MS in people with CKD.

Hand Sewn Anastomosis Skill Acquisition and In Vivo Transfer Using 3D-Printed Small Bowel Simulator

INTRODUCTION

General surgery residents need to master the hand-sewn bowel anastomosis (HSBA) technique. However, practice opportunities outside of the operating room are rare, and commercial simulators are often costly. The objective of this study is to assess the efficacy of a new, affordable silicone small bowel simulator, made with a three-dimensional (3D) printed mold, as a training tool to learn this technique.

METHODS

This was a single-blinded pilot randomized controlled trial comparing two groups of eight junior surgical residents. All participants completed a pretest using an inexpensive, custom developed 3D-printed simulator. Next, participants randomized to the experimental group practiced the HSBA skill at home (eight sessions), while those randomized to the control group did not receive any hands-on practice opportunities. A posttest was done using the same simulator as for the pretest and practice sessions, and the retention-transfer test was performed on an anesthetized porcine model. Pretests, posttests and retention-transfer tests were filmed and graded by a blinded evaluator using assessments of technical skills, quality of final product, and tests of procedural knowledge.

RESULTS

The experimental group significantly improved after practicing with the model (P = 0.01), while an equivalent improvement was not noted in the control group (P = 0.07). Moreover, the experimental group's performance remained stable between the posttest and the retention-transfer test (P = 0.95).

CONCLUSIONS

Our 3D-printed simulator is an affordable and efficacious tool to teach residents the HSBA technique. It allows development of surgical skills that are transferable to an in vivo model.

3D-printed procedural task trainer for the aspiration of penile corpus cavernosa in ischaemic priapism

OBJECTIVE

The development and initial clinical assessment of a novel 3D-printed procedural task trainer for the aspiration of penile corpus cavernosa in ischaemic priapism.

METHODS

A task trainer for the aspiration of penile corpus cavernosa was designed and manufactured using commercially available 3D printing equipment. The trainer was assessed in two separate training sessions led by faculty investigators. Participants in the sessions were asked to complete a post-procedure survey with regards to the utility and realism of the task trainer.

RESULTS

The participants (n = 14) covered a broad spectrum of clinician types. The trainer was perceived by the participants as being anatomically realistic, and especially while under drapes provided a reasonable facsimile of real clinical setup. The trainer proved resilient to multiple attempts at aspiration by multiple participants.

CONCLUSIONS

Participant and facilitator feedback indicates that the task trainer is a useful platform to train for what is a low frequency, but high stakes, procedure. Small numbers of participants preclude statistical rigour and certainty regarding overall performance of the trainer. However, the uniformity in the responses would suggest that this is indeed a task trainer that is 'fit for purpose'.

Application of 3D Printing in Bone Grafts

The application of 3D printing in bone grafts is gaining in importance and is becoming more and more popular. The choice of the method has a direct impact on the preparation of the patient for surgery, the probability of rejection of the transplant, and many other complications. The aim of the article is to discuss methods of bone grafting and to compare these methods. This review of literature is based on a selective literature search of the PubMed and Web of Science databases from 2001 to 2022 using the search terms “bone graft”, “bone transplant”, and “3D printing”. In addition, we also reviewed non-medical literature related to materials used for 3D printing. There are several methods of bone grafting, such as a demineralized bone matrix, cancellous allograft, nonvascular cortical allograft, osteoarticular allograft, osteochondral allograft, vascularized allograft, and an autogenic transplant using a bone substitute. Currently, autogenous grafting, which involves removing the patient’s bone from an area of low aesthetic importance, is referred to as the gold standard. 3D printing enables using a variety of materials. 3D technology is being applied to bone tissue engineering much more often. It allows for the treatment of bone defects thanks to the creation of a porous scaffold with adequate mechanical strength and favorable macro- and microstructures. Bone tissue engineering is an innovative approach that can be used to repair multiple bone defects in the process of transplantation. In this process, biomaterials are a very important factor in supporting regenerative cells and the regeneration of tissue. We have years of research ahead of us; however, it is certain that 3D printing is the future of transplant medicine.

Simulation device for shoulder reductions: overview of prototyping, testing, and design instructions

BACKGROUND

Shoulder dislocations are common occurrences, yet there are few simulation devices to train medical personnel on how to reduce these dislocations. Reductions require a familiarity with the shoulder and a nuanced motion against strong muscle tension. The goal of this work is to describe the design of an easily replicated, low-cost simulator for training shoulder reductions.

MATERIALS AND METHODS

An iterative, stepwise engineering design process was used to design and implement ReducTrain. A needs analysis with clinical experts led to the selection of the traction-countertraction and external rotation methods as educationally relevant techniques to include. A set of design requirements and acceptance criteria was established that considered durability, assembly time, and cost. An iterative prototyping development process was used to meet the acceptance criteria. Testing protocols for each design requirement are also presented. Step-by-step instructions are provided to allow the replication of ReducTrain from easily sourced materials, including plywood, resistance bands, dowels, and various fasteners, as well as a 3D-printed shoulder model, whose printable file is included at a link in the Additional file 1: Appendix.

RESULTS

A description of the final model is given. The total cost for all materials for one ReducTrain model is under US $200, and it takes about 3 h and 20 min to assemble. Based on repetitive testing, the device should not see any noticeable changes in durability after 1000 uses but may exhibit some changes in resistance band strength after 2000 uses.

DISCUSSION

The ReducTrain device fills a gap in emergency medicine and orthopedic simulation. Its wide variety of uses points to its utility in several instructional formats. With the rise of makerspaces and public workshops, the construction of the device can be easily completed. While the device has some limitations, its robust design allows for simple upkeep and a customizable training experience.

CONCLUSION

A simplified anatomical design allows for the ReducTrain model to serve as a viable training device for shoulder reductions.

Advances in 3D bioprinting technology for functional corneal reconstruction and regeneration

Corneal transplantation constitutes one of the major treatments in severe cases of corneal diseases. The lack of cornea donors as well as other limitations of corneal transplantation necessitate the development of artificial corneal substitutes. Biosynthetic cornea model using 3D printing technique is promising to generate artificial corneal structure that can resemble the structure of the native human cornea and is applicable for regenerative medicine. Research on bioprinting artificial cornea has raised interest into the wide range of materials and cells that can be utilized as bioinks for optimal clarity, biocompatibility, and tectonic strength. With continued advances in biomaterials science and printing technology, it is believed that bioprinted cornea will eventually achieve a level of clinical functionality and practicality as to replace donated corneal tissues, with their associated limitations such as limited or unsteady supply, and possible infectious disease transmission. Here, we review the literature on bioprinting strategies, 3D corneal modelling, material options, and cellularization strategies in relation to keratoprosthesis design. The progress, limitations and expectations of recent cases of 3D bioprinting of artifial cornea are discussed. An outlook on the rise of 3D bioprinting in corneal reconstruction and regeneration is provided.

Process-oriented metrics to provide feedback and assess the performance of students who are learning surgical procedures: The percutaneous dilatational tracheostomy case

PURPOSE

Assessing competency in surgical procedures is key for instructors to distinguish whether a resident is qualified to perform them on patients. Currently, assessment techniques do not always focus on providing feedback about the order in which the activities need to be performed. In this research, using a Process Mining approach, process-oriented metrics are proposed to assess the training of residents in a Percutaneous Dilatational Tracheostomy (PDT) simulator, identifying the critical points in the execution of the surgical process.

MATERIALS AND METHODS

A reference process model of the procedure was defined, and video recordings of student training sessions in the PDT simulator were collected and tagged to generate event logs. Three process-oriented metrics were proposed to assess the performance of the residents in training.

RESULTS

Although the students were proficient in classic metrics, they did not reach the optimum in process-oriented metrics. Only in 25% of the stages the optimum was achieved in the last session. In these stages, the four more challenging activities were also identified, which account for 32% of the process-oriented metrics errors.

CONCLUSIONS

Process-oriented metrics offer a new perspective on surgical procedures performance, providing a more granular perspective, which enables a more specific and actionable feedback for both students and instructors.

A Novel Ocular Tonometry Task Trainer

The measurement of intraocular pressure via ocular tonometry is a skill necessary for the evaluation of emergency department patients with ocular complaints. Accurate results inform the use of time-sensitive medications or invasive procedures. We sought to develop and evaluate an affordable, realistic, and reproducible task trainer to allow Emergency Medicine residents and medical students to practice tonometry. We placed an angiocatheter into the vitreous chamber of a swine eye through the optic nerve stump and sealed it with a purse string suture and cyanoacrylate glue. This allowed us to connect intravenous extension tubing and use a saline-filled syringe to repeatedly adjust intraocular pressure in real time. Optionally, this model can be mounted in a polystyrene foam mannequin head to enhance realism and facilitate practice. The task trainer was implemented in medical student and Emergency Medicine resident education at Vanderbilt University Medical Center. Thirty-six learners participated in the study, all of whom completed pre-course and post-course surveys. Among all learners, the mean comfort with performing tonometry improved significantly (3.26 to 7.64 {Z = -4.95, p < 0.005}). The mean confidence in the accuracy of measurements also increased (3.11 to 7.56 {Z = -4.8, p < 0.005}). On a 10-point scale, learners felt this task trainer was highly helpful in increasing their comfort with and the ability to perform tonometry (mean 9.19 {SD 1.19}). We have developed a low-cost and easily constructed ocular tonometry task trainer that resulted in significant improvement in learner comfort and confidence.

Multidisciplinary Simulation Improves Resident Confidence for Pregnant Patients Requiring Surgical Intervention

Introduction: Hepatocellular adenomas are a rare but serious cause of bleeding, which is further complicated by pregnancy. Interprofessional cooperation is a key component of residency education, thus simulations designed to integrate multiple programs are mutually beneficial. This simulation details surgical and obstetric management of a pregnant patient in hemorrhagic shock from a bleeding hepatocellular adenoma. Objectives for the study were to evaluate learners’ confidence to 1) prioritize the care of a pregnant patient with hemoperitoneum and hemorrhagic shock, 2) demonstrate interdisciplinary collaboration with other specialties, 3) apply massive transfusion protocol (MTP) in the appropriate clinical setting, and 4) analyze critical decisions for evaluating pregnant females with severe abdominal pain.

Methods: Obstetric, general surgery, and anesthesia residents, along with labor and delivery nurses participated in a simulated clinical scenario that focused on the management of a pregnant patient in hemorrhagic shock. The learners evaluated the educational session using a standard Return on Investment in Learning survey immediately following the session.

Results: A total of 23 residents and medical students gave feedback on the experience. The main learning objectives were met with increased confidence in the four learning objectives by 77.3-95.4% of responders. Overall, greater than 90% of participants felt the simulation was relevant to their training and realistic, with 100% responding that the course provided new, or clarified existing information for them.

Conclusion: A multidisciplinary simulation-based educational intervention was successful in improving learner confidence in managing a complicated surgical emergency in a pregnant patient with inter-residency cooperation.

Development and Learner-Based Assessment of a Novel, Customized, 3D Printed Small Bowel Simulator for Hand-Sewn Anastomosis Training

Hand-sewn bowel anastomosis (HSBA) is an essential skill for surgical residents to learn, as it is used in numerous surgical procedures. However, the opportunities to practice this skill before attempting it on patients are limited. Practice on simulators can help improve this technique, but there is a paucity of realistic, cost-efficient simulators for the acquisition of HSBA skills.

This technical report describes the development of our simulator that consists of a small bowel manufactured from silicone and a 3D-printed clamp system to hold the bowel in place. Our simulator was co-designed by a clinical team of surgeons and then assessed for perceived acceptability and effectiveness by 16 junior residents in various surgical specialties at our faculty. A majority of the learners rated our simulator to be a good or very good learning tool for HSBA, although they suggested some minor improvements.

Overall, our silicone small bowel model appears to be an effective and inexpensive way to acquire this surgical skill.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

Role of 3D printing technology in paediatric teaching and training: a systematic review

BACKGROUND

In the UK, undergraduate paediatric training is brief, resulting in trainees with a lower paediatric knowledge base compared with other aspects of medicine. With congenital conditions being successfully treated at childhood, adult clinicians encounter and will need to understand these complex pathologies. Patient-specific 3D printed (3DP) models have been used in clinical training, especially for rarer, complex conditions. We perform a systematic review to evaluate the evidence base in using 3DP models to train paediatricians, surgeons, medical students and nurses.

METHODS

Online databases PubMed, Web of Science and Embase were searched between January 2010 and April 2020 using search terms relevant to "paediatrics", "education", "training" and "3D printing". Participants were medical students, postgraduate trainees or clinical staff. Comparative studies (patient-specific 3DP models vs traditional teaching methods) and non-comparative studies were included. Outcomes gauged objective and subjective measures: test scores, time taken to complete tasks, self-reported confidence and personal preferences on 3DP models. If reported, the cost of and time taken to produce the models were noted.

RESULTS

From 587 results, 15 studies fit the criteria of the review protocol, with 5/15 being randomised controlled studies and 10/15 focussing on cardiovascular conditions. Participants using 3DP models demonstrated improved test scores and faster times to complete procedures and identify anatomical landmarks compared with traditional teaching methods (2D diagrams, lectures, videos and supervised clinical events). User feedback was positive, reporting greater user self-confidence in understanding concepts with users wishing for integrated use of 3DP in regular teaching. Four studies reported the costs and times of production, which varied depending on model complexity and printer. 3DP models were cheaper than 'off-the-shelf' models available on the market and had the benefit of using real-world pathologies. These mostly non-randomised and single-centred studies did not address bias or report long-term or clinically translatable outcomes.

CONCLUSIONS

3DP models were associated with greater user satisfaction and good short-term educational outcomes, with low-quality evidence. Multicentred, randomised studies with long-term follow-up and clinically assessed outcomes are needed to fully assess their benefits in this setting.

PROSPERO REGISTRATION NUMBER

CRD42020179656.

A focused simulation-based optimization of print time and material usage with respect to orientation, layer height and support settings for multi-pathological anatomical models in inverted vat photopolymerization 3D printing

Background

3D printing of anatomical models requires multi-factorial decision making for optimal model manufacturing. Due to the complex nature of the printing process, there are frequently multiple potentialities based on the desired end goal. The task of identifying the most optimal combination of print control variables is inherently subjective and rests on sound operator intuition. This study investigates the effect of orientation, layer and support settings on print time and material usage. This study also presents a quantitative optimization framework to jointly optimize print time and material usage as a function of those settings for multi-pathological anatomical models.

Methods

Seven anatomical models representing different anatomical regions (cardiovascular, abdominal, neurological and maxillofacial) were selected for this study. A reference cube was also included in the simulations. Using PreForm print preparation software the print time and material usage was simulated for each model across 4 orientations, 2 layer heights, 2 support densities and 2 support tip sizes. A 90–10 weighted optimization was performed to identify the 5 most optimal treatment combinations that resulted in the lowest print time (90% weight) and material usage (10% weight) for each model.

Results

The 0.1 mm layer height was uniformly the most optimal setting across all models. Layer height had the largest effect on print time. Orientation had a complex effect on both print time and material usage in certain models. The support density and the support tip size settings were found to have a relatively minor effect on both print time and material usage. Hollow models had a larger support volume fraction compared to solid models.

Conclusions

The quantitative optimization framework identified the 5 most optimal treatment combinations for each model using a 90–10 weighting for print time and material usage. The presented optimization framework could be adapted based on the individual circumstance of each 3D printing lab and/or to potentially incorporate additional response variables of interest.

Three-Dimensional Modeling in Training, Simulation, and Surgical Planning in Open Vascular and Endovascular Neurosurgery: A Systematic Review of the Literature

BACKGROUND

The expanding use of three-dimensional (3D) printing in open vascular and endovascular neurosurgery presents a promising new tool in resident learning as well as operative planning. Recent studies have investigated the accuracy, efficacy, and practicality of 3D-printed models of patient-specific disease.

OBJECTIVE

To review the literature exploring 3D modeling in neurovascular and endovascular surgery for training, simulation, and surgical preparation.

METHODS

A systematic search of the PubMed database was conducted using keywords relating to 3D printing and neurovascular or endovascular surgery. Articles were manually screened to include those that focused on resident training, surgical simulation, or preoperative planning. Information on fabrication method, materials, cost, and validation measures was collected.

RESULTS

A total of 27 articles were identified that met inclusion criteria. Twenty-one studies used 3D printing to produce aneurysm models, 5 produced arteriovenous malformation models, and 1 produced aneurysm and arteriovenous malformation models. Stereolithography was the most common fabrication method used, with acrylonitrile butadiene styrene and VeroClearTangoPlus (Stratasys) being the most frequently used materials. The mean manufacturing cost per model was U.S. $624.83. Outcomes included model measurement accuracy, concordance of intraoperative devices with those selected preoperatively, and qualitative feedback.

CONCLUSIONS

Models generated by 3D printing are anatomically accurate and aid in resident learning as well as operative planning in open vascular and endovascular neurosurgery. As advancements in printing methods are made and manufacturing costs decrease, this tool may supplement training on a wider scale in a field in which direct exposure to cases is limited.

Metodologias ativas no cateterismo periférico venoso: desenvolvimento de habilidades com simulador de baixo custo

RESUMO Objetivo Conhecer a percepção de estudantes de enfermagem sobre a contribuição do uso do simulador de baixo custo no desenvolvimento de habilidades técnicas para o cateterismo periférico venoso. Método Estudo descritivo de abordagem qualitativa, realizado em universidade pública do sul do Brasil com 25 estudantes de enfermagem. Os dados foram coletados em 2019, por meio de questionário acerca do cateterismo periférico venoso, desenvolvido com apoio de simulador de baixo custo. Para análise, seguiu-se a proposta operativa de Minayo. Resultados A partir dos dados, surgiram duas categorias. 1) Desenvolvimento de habilidades para cateterismo periférico venoso: os estudantes apontaram que o uso do simulador possibilita compreender cada etapa do procedimento e identificar onde precisam aperfeiçoar a técnica, preparando-os para o contato com o paciente. 2) Dificuldades encontradas na utilização do simulador de baixo custo. Os estudantes destacaram a baixa fidelidade do simulador e a limitação do treinamento por simulação sem comunicação. Conclusões e implicações para a prática Os estudantes percebem o simulador de baixo custo como uma relevante ferramenta para o desenvolvimento de habilidades do cateterismo periférico venoso, sugerem seu aperfeiçoamento para aumentar a fidelidade e a incorporação da comunicação no momento da punção para o maior realismo da experiência simulada.

The Manufacturing of 3D Printed models for the Neurotraumatological Education of Military Surgeons

Introduction

When deployed abroad, military surgeons frequently have to deal with casualties involving head trauma. The emergency treatments, as well as craniotomies, are often performed by non-neurosurgeons qualified with basic neurotraumatological skills. Previous neurotrauma courses for education of non-neurosurgeons in Germany teach surgical emergency skills but do not include the training of skills needed to successfully utilize imaging in surgical planning, which is of importance for the safety and success of the treatment. To overcome these limitations, 3D printed models of neurotrauma cases were fabricated for application in the training of non-neurosurgeons.

Materials and Methods

Five models of actual neurotrauma cases from our neurosurgical department were segmented from CT scans and 3D printed using multi-part fused deposition modeling. Model quality was assessed with respect to the representation of pre-defined anatomical landmarks. The models were then fixed to a wooden mount with a central light source and covered by a latex mask for skin simulation. Surgical planning by means of craniometric measurements on the basis of available CT scans of the corresponding patients was then applied to the model.

Results

The 3D printed models precisely represented the cranium, the lesion, and anatomical landmarks, which are taken into consideration during surgical planning. Surface covering with washable latex masks ensured sufficient masking of the now non-noticeable lesion within the semi-translucent skull. Surgical planning was performed using washable marker drawings. When lighted, the otherwise non-visible lesion within the semi-translucent 3D printed craniums became visible and facilitated immediate success control for the course participants.

Conclusion

The presented method provided a way to fabricate precise 3D models of neurotrauma cases, which are suitable to teach the application of medical imaging in surgical planning. For further benefit analysis, the application of the presented education tool needs to be investigated within a neurotrauma course.

3D printed bismuth oxide-polylactic acid composites for radio-mimetic computed tomography spine phantoms

Polylactic acid (PLA) composite filaments with varying concentrations of bismuth oxide microparticle additives were fabricated for use with commercially available fused filament fabrication (FFF) printing systems for the production of spine phantoms that mimic the radiopacity of bone. Thermal analysis showed that the additives had limited impact on the glass transition temperature and melting point of the filaments, allowing for their use in commercial FFF systems with standard printer settings. The ultimate strength of the printed test specimens was found to reduce slightly when bismuth oxide was added in high concentrations, with a moderate reduction of 12% compared to PLA at the highest concentration of 30 wt%. The modulus of the specimens increased by up to 24% with the addition of the additive. The radiopacity of specimens printed with the composite filaments were measured by X-ray microcomputed tomography (micro-CT) and clinical computed tomography (CT). The CT number was found to increase by approximately 196 HU per wt% of bismuth oxide added to the filaments. A phantom model of a cervical spine deformity was successfully printed by FFF with a composite filament which was calibrated to mimic the radiopacity of cervical and cortical bone. The results indicate that the composite filaments have direct applicability for the production of phantoms used for education and preoperative planning.

Evaluation of a Patient-Specific, Low-Cost, 3-Dimensional-Printed Transesophageal Echocardiography Human Heart Phantom

OBJECTIVE

Currently available 3-dimensional (3D) modeling and printing techniques allow for the creation of patient-specific models based on 3D medical imaging data. The authors hypothesized that a low-cost, patient-specific, cardiac computed tomography-based phantom, created using desktop 3D printing and casting, would have comparable image quality, accuracy, and usability to an existing commercially available echocardiographic phantom.

DESIGN

Blinded comparative study.

SETTING

Simulation laboratory at a single academic institution.

PARTICIPANTS

Voluntary cardiac anesthesiologists at a single academic institution.

INTERVENTIONS

Stage 1 of the study consisted of an online questionnaire in which a set of basic transesophageal echocardiography (TEE) views obtained from the 3D printed phantom and commercial phantom were presented to participants, who had to identify the views and evaluate their fidelity to clinical images on a Likert scale. In stage 2, participants performed an unblinded basic TEE examination on both phantoms.

MEASUREMENTS AND MAIN RESULTS

The time needed to acquire each basic view was recorded. Overall usability of the phantoms was assessed through a questionnaire. The participants could recognize most of the views. Fidelity ratings for both phantoms were similar (p < 0.05), with the exception of a midesophageal 2-chamber view that was observed better on the 3D printed phantom. The time required to obtain the views was shorter for the 3D printed phantom, although not statistically significant for most views. The overall user experience was better for the 3D phantom for all categories examined (p < 0.05).

CONCLUSIONS

The study suggested that a 3D-printed TEE phantom is comparable with the commercially available one with good usability.

Investigation of the "Superior Facet Rule" Using 3D-Printed Thoracic Vertebrae With Simulated Corticocancellous Interface

BACKGROUND

Pedicle screw placement is the most common method of fixation in the thoracic spine. Use of the "superior facet rule" allows the operator to locate the borders of the pedicle reliably using posterior landmarks alone. This study investigated the ability of 3-dimensionally (3D)-printed thoracic vertebrae, made from combined thermoplastic polymers, to demonstrate pedicle screw cannulation accurately using the superior facet as a reliable landmark.

METHODS

An anonymized computed tomography scan of the thoracic spine was obtained. The T1-T12 thoracic vertebrae were anatomically segmented and 3D-printed. The pedicle diameters and distance from the midpoint of the superior facet to the ventral lamina were recorded. A total of 120 thoracic pedicles in 60 thoracic vertebral models were instrumented using a freehand technique based only on posterior landmarks. The vertebral models were then coronally cut and examined for medial or lateral violations of the pedicle after screw placement.

RESULTS

A total of 120 pedicle screws were placed successfully within the 3D-printed thoracic vertebral models. Average measurements fell within 1 standard deviation of previous population studies. There were no pedicle wall violations using standard posterior element landmarks for instrumentation. There were 3 lateral violations of the vertebral body wall during screw placement, all attributable to the insertion technique.

CONCLUSIONS

3D-printed thoracic vertebral models using combined thermoplastic polymers can accurately demonstrate the anatomical ultrastructure and posterior element relationships of the superior facet rule for safe thoracic pedicle screw placement. This method of vertebral model prototyping could prove useful for surgical education and demonstrating spinal anatomy.

Cost-Effective Method for 3-Dimensional Printing Dynamic Multiobject and Patient-Specific Brain Tumor Models: Technical Note

BACKGROUND

Three-dimensional (3D) printing is a powerful tool for replicating patient-specific anatomic features for education and surgical planning. The advent of "desktop" 3D printing has created a cost-effective and widely available means for institutions with limited resources to implement a 3D-printing workflow into their clinical applications. The ability to physically manipulate the desired components of a "dynamic" 3D-printed model provides an additional dimension of anatomic understanding. There is currently a gap in the literature describing a cost-effective and time-efficient means of creating dynamic brain tumor 3D-printed models.

METHODS

Using free, open-access software (3D Slicer) for patient imaging to Standard Tessellation Language file conversion, as well as open access Standard Tessellation Language editing software (Meshmixer), both intraaxial and extraaxial brain tumor models of patient-specific pathology are created.

RESULTS

A step-by-step methodology and demonstration of the software manipulation techniques required for creating cost-effective, multidimensional brain tumor models for patient education and surgical planning are exhibited using a detailed written guide, images, and a video display.

CONCLUSIONS

In this technical note, we describe in detail the specific functions of free, open-access software and desktop 3D printing techniques to create dynamic and patient-specific brain tumor models for education and surgical planning.

Investigation of a three-dimensional printed dynamic cervical spine model for anatomy and physiology education

INTRODUCTION

Three-dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high-resolution segmentation and 3D-printingtechnique was investigated for the creation of a dynamic educational model.

METHODS

An anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high-resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3-7 vertebrae were 3D-printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in-vivo measurements. The flexible 3D-printed model was then compared to a static 3D-printed model to determine the educational benefit of demonstrating physiologic concepts.

RESULTS

The canal diameter changes on the flexible 3D-printed model accurately reflected in-vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D-printed model to a cohort of learners.

CONCLUSIONS

Dynamic 3D-printed models can provide educators with a cost-effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex-vivo modeling of case-specific physiologic and pathologic conditions.

The SpineBox: A Freely Available, Open-access, 3D-printed Simulator Design for Lumbar Pedicle Screw Placement

Background

The recent COVID-19 pandemic has demonstrated the need for innovation in cost-effective and easily produced surgical simulations for trainee education that are not limited by physical confines of location. This can be accomplished with the use of desktop three-dimensional (3D) printing technology. This study describes the creation of a low-cost and open-access simulation for anatomical learning and pedicle screw placement in the lumbar spine, which is termed the SpineBox.

Materials and methods

An anonymized CT scan of the lumbar spine was obtained and converted into 3D software files of the L1-L5 vertebral bodies. A computer-assisted design (CAD) software was used to assemble the vertebral models into a simulator unit in anatomical order to produce an easily prototyped simulator. The printed simulator was layered with foam in order to replicate soft tissue structures. The models were instrumented with pedicle screws using standard operative technique and examined under fluoroscopy.

Results

Ten SpineBoxes were created using a single desktop 3D printer, with accurate replication of the cortico-cancellous interface using previously validated techniques. The models were able to be instrumented with pedicle screws successfully and demonstrated quality representation of bony structures under fluoroscopy. The total cost of model production was under $10.

Conclusion

The SpineBox represents the first open-access simulator for the instruction of spinal anatomy and pedicle screw placement. This study aims to provide institutions across the world with an economical and feasible means of spine surgical simulation for neurosurgical trainees and to encourage other rapid prototyping laboratories to investigate innovative means of creating educational surgical platforms in the modern era.