Three-Dimensional Printed Models for Lateral Skull Base Surgical Training: Anatomy and Simulation of the Transtemporal Approaches

BACKGROUND

Three-dimensional (3D) printing holds great potential for lateral skull base surgical training; however, studies evaluating the use of 3D-printed models for simulating transtemporal approaches are lacking.

OBJECTIVE

To develop and evaluate a 3D-printed model that accurately represents the anatomic relationships, surgical corridor, and surgical working angles achieved with increasingly aggressive temporal bone resection in lateral skull base approaches.

METHODS

Cadaveric temporal bones underwent thin-slice computerized tomography, and key anatomic landmarks were segmented using 3D imaging software. Corresponding 3D-printed temporal bone models were created, and 4 stages of increasingly aggressive transtemporal approaches were performed (40 total approaches). The surgical exposure and working corridor were analyzed quantitatively, and measures of face validity, content validity, and construct validity in a cohort of 14 participants were assessed.

RESULTS

Stereotactic measurements of the surgical angle of approach to the mid-clivus, residual bone angle, and 3D-scanned infill volume demonstrated comparable changes in both the 3D temporal bone models and cadaveric specimens based on the increasing stages of transtemporal approaches (PANOVA <.003, <.007, and <.007, respectively), indicating accurate representation of the surgical corridor and working angles in the 3D-printed models. Participant assessment revealed high face validity, content validity, and construct validity.

CONCLUSION

The 3D-printed temporal bone models highlighting key anatomic structures accurately simulated 4 sequential stages of transtemporal approaches with high face validity, content validity, and construct validity. This strategy may provide a useful educational resource for temporal bone anatomy and training in lateral skull base approaches.

Sterility of 3D-Printed Orthopedic Implants Using Fused Deposition Modeling

The use of 3-dimensional (3D) printing in orthopedics is developing rapidly and impacting the areas of preoperative planning, surgical guides, and simulation. As this technology continues to improve, the greatest impact of 3D printing may be in low- and middle-income countries where surgical items are in short supply. This study investigated sterility of 3D-printed ankle fracture fixation plates and cortical screws. The hypothesis was that the process of heated extrusion in fused deposition modeling printing would create sterile prints in a timely fashion that would not require postproduction sterilization. A free computer-assisted design program was used to design the implant models. One control group and 8 study groups were printed. Print construct, orientation, size, and postproduction sterilization differed among the groups. Sterility was assessed using thioglycollate broth cultures at 24 hours, 48 hours, and 7 days. Positive growth was speciated for aerobic and anaerobic bacteria. Print time and failed prints were recorded. Control samples were 100% positive for bacterial growth. All test samples remained sterile at all time points (100%). Speciation of control samples was obtained, and Staphylococcus was the most common species. Print times varied; however, no print time exceeded 6.75 minutes. Eighteen prints (17%) failed in the printing process. These findings demonstrate an intrinsic sterilization process associated with fused deposition modeling 3D printing and indicate the feasibility of 3D-printed surgical implants and equipment for orthopedic applications. With future research, 3D-printed implants may be a treatment modality to assist orthopedic surgeons in low- and middle-income countries. [Orthopedics. 2020; 43(1): 46-51.].

Three-dimensional printing as a tool in otolaryngology training: a systematic review

OBJECTIVE

Three-dimensional printing is a revolutionary technology that is disrupting the status quo in surgery. It has been rapidly adopted by otolaryngology as a tool in surgical simulation for high-risk, low-frequency procedures. This systematic review comprehensively evaluates the contemporary usage of three-dimensional printed otolaryngology simulators.

METHOD

A systematic review of the literature was performed with narrative synthesis.

RESULTS

Twenty-two articles were identified for inclusion, describing models that span a range of surgical tasks (temporal bone dissection, airway procedures, functional endoscopic sinus surgery and endoscopic ear surgery). Thirty-six per cent of articles assessed construct validity (objective measures); the other 64 per cent only assessed face and content validity (subjective measures). Most studies demonstrated positive feedback and high confidence in the models' value as additions to the curriculum.

CONCLUSION

Whilst further studies supported with objective metrics are merited, the role of three-dimensional printed otolaryngology simulators is poised to expand in surgical training given the enthusiastic reception from trainees and experts alike.

Three-dimensional Printing Technology in Orthopaedics

Three-dimensional (3-D) printing technology is affecting how orthopaedic surgeries are planned and executed. Like many innovations, 3-D printers are becoming smaller, more affordable, and more accessible. Free access to open-source 3-D imaging software has also made clinical implementation of this technology widely feasible. Within the last decade, 3-D printing advancements have improved the way orthopaedic surgeons can approach both common and complex cases. Advanced imaging studies can be used to create musculoskeletal models, which can then be used to create custom orthopaedic guides and instruments. Similarly, 3-D printing is being applied to improve the field of biologic therapies in orthopaedics. Application of 3-D printing technology has been associated with important improvements in education, preoperative planning, surgical care, and patient-specific devices and treatments. Improvements in cost-effectiveness, access, and usability of 3-D printing technology have made it possible for orthopaedic surgeons to use this powerful tool using desktop 3-D printers in their clinic or office. The types of printers and materials available to print are constantly expanding, but many of the basic 3-D printing principles persist throughout these advances in the field. A clear understanding of this technology is important to the clinical implementation of 3-D printing for current and future practice of orthopaedic care.

The Effects of a Functional Three-dimensional (3D) Printed Knee Joint Simulator in Improving Anatomical Spatial Knowledge

In recent decades, three-dimensional (3D) printing as an emerging technology, has been utilized for imparting human anatomy knowledge. However, most 3D printed models are rigid anatomical replicas that are unable to represent dynamic spatial relationships between different anatomical structures. In this study, the data obtained from a computed tomography (CT) scan of a normal knee joint were used to design and fabricate a functional knee joint simulator for anatomical education. Utility of the 3D printed simulator was evaluated in comparison with traditional didactic learning in first-year medical students (n = 35), so as to understand how the functional 3D simulator could assist in their learning of human anatomy. The outcome measure was a quiz comprising 11 multiple choice questions based on locking and unlocking of the knee joint. Students in the simulation group (mean score = 85.03%, ±SD 10.13%) performed significantly better than those in the didactic learning group, P < 0.05 (mean score = 70.71%, ±SD 15.13%), which was substantiated by large effect size, as shown by a Cohen's d value of 1.14. In terms of learning outcome, female students who used 3D printed simulators as learning aids achieved greater improvement in their quiz scores as compared to male students in the same group. However, after correcting for the modality of instruction, the sex of the students did not have a significant influence on the learning outcome. This randomized study has demonstrated that the 3D printed simulator is beneficial for anatomical education and can help in enriching students' learning experience.

Safety of Drilling 3-Dimensional-Printed Temporal Bones

Importance

Three-dimensional (3-D) printing of temporal bones is becoming more prevalent. However, there has been no measure of the safety of drilling these models to date. It is unknown whether the heat and sheer from the drill may create harmful volatile organic compounds (VOCs).

Objective

To determine the level of exposure to airborne contaminants when conducting high-speed drilling on 3-D-printed models and to explore whether there is a need for exposure control measures.

Design, Setting, and Participants

In this occupational safety assessment carried out in a temporal bone laboratory, 3 individual 3-D-printed temporal bones were made using 3 different materials commonly cited in the literature: polylactic acid (PLA), photoreactive acrylic resin (PAR), and acrylonitrile butadiene styrene (ABS). Each model was drilled for 40 minutes while the surgeon wore a sampling badge. Sampling was conducted for airborne concentrations of VOCs and total particulate (TP). Monitoring for VOCs was conducted using Assay Technology 521-25 organic vapor badge worn at the surgeon's neckline. Monitoring for TP was conducted using a polyvinyl chloride filter housed inside a cassette and coupled with an SKC AirChek 52 personal air-sampling pump. Samples were collected and analyzed in accordance with NIOSH Method 500.

Main Outcomes and Measures

Presence of VOCs and TP count exposures at Occupational Safety and Health Administration (OSHA) actionable levels.

Results

Results of the VOC sample were less than detection limits except for isopropyl alcohol at 0.24 ppm for PAR. The TP samples were less than the detection limit of 1.4 mg/m3. The results are below all applicable OSHA Action Levels and Permissible Exposure Limits for all contaminants sampled for.

Conclusions and Relevance

Drilling 3-D-printed models made from PLA, ABS, and PAR was safe by OSHA standards. Continued monitoring and safety testing are needed as 3-D-printed technologies are introduced to our specialty.

Assessment of Middle Ear Anatomy Teaching Methodologies Using Microscopy versus Endoscopy: A Randomized Comparative Study

Teaching methodologies for the anatomy of the middle ear have not been investigated greatly due to the middle ear's highly complex structure and hidden location inside of the temporal bone. The aim of this randomized study was to quantitatively compare the suitability of using microscope- and endoscope-based methods for teaching the anatomy of the middle ear. We hypothesize that the endoscopic approach will be more efficient compared to the microscopic approach. To answer the study questions, 33 sixth-year medical students, residents and otorhinolaryngology specialists were randomized either into the endoscopy or the microscopy group. Their anatomical knowledge was assessed using a structured anatomical knowledge test before and after each session. Each participant received tutoring on a human cadaveric specimen using one of the two methods. They then performed a hands-on dissection. After 2-4 weeks, the same educational curriculum was repeated using the other technique. The mean gains in anatomical knowledge for the specialists, residents, and medical students were +19.0%, +34.6%, and +23.4%, respectively. Multivariate analyses identified a statistically significant increase in performance for the endoscopic method compared to the microscopic technique (P < 0.001). For the recall of anatomical structures during dissection, the endoscopic method outperformed the microscopic technique independently of the randomization or the prior training level of the attendees (P < 0.001). In conclusion, the endoscopic approach to middle ear anatomy education is associated to an improved gain in knowledge as compared to the microscopic approach. The participants subjectively preferred the endoscope for educational purposes.

3D-printed pediatric temporal bone models for surgical training: a patient-specific and low-cost alternative

Aim: To determine the usefulness of low-cost 3D-printed pediatric temporal bone models and to define if they could be used as a tool for large-scale surgical training based on their affordability. Materials & methods: Prototypes of a pediatric temporal bone were printed using fused deposition modeling 3D printing technique. The prototypes were drilled. The surgical simulation experience was registered by means of a Likert scale questionnaire. Results: The prototypes adequately simulated a cadaveric temporal bone. The costs associated with production were low compared with other commercial models making it a cost-effective alternative for a temporal bone laboratory. Conclusion: Printed temporal bones created by means of fused deposition modeling are useful for surgical simulation and training in otolaryngology, and it is possible to achieve detailed low-cost models.

Development of augmented-reality applications in otolaryngology-head and neck surgery

OBJECTIVES/HYPOTHESIS

Augmented reality (AR) allows for the addition of transparent virtual images and video to one's view of a physical environment. Our objective was to develop a head-worn, AR system for accurate, intraoperative localization of pathology and normal anatomic landmarks during open head and neck surgery.

STUDY DESIGN

Face validity and case study.

METHODS

A protocol was developed for the creation of three-dimensional (3D) virtual models based on computed tomography scans. Using the HoloLens AR platform, a novel system of registration and tracking was developed. Accuracy was determined in relation to actual physical landmarks. A face validity study was then performed in which otolaryngologists were asked to evaluate the technology and perform a simulated surgical task using AR image guidance. A case study highlighting the potential usefulness of the technology is also presented.

RESULTS

An AR system was developed for intraoperative 3D visualization and localization. The average error in measurement of accuracy was 2.47 ± 0.46 millimeters (1.99, 3.30). The face validity study supports the potential of this system to improve safety and efficiency in open head and neck surgical procedures.

CONCLUSIONS

An AR system for accurate localization of pathology and normal anatomic landmarks of the head and neck is feasible with current technology. A face validity study reveals the potential value of the system in intraoperative image guidance. This application of AR, among others in the field of otolaryngology-head and neck surgery, promises to improve surgical efficiency and patient safety in the operating room.

LEVEL OF EVIDENCE

2b Laryngoscope, 129:S1-S11, 2019.

Multi-material three dimensional printed models for simulation of bronchoscopy

Background

Bronchoscopy involves exploration of a three-dimensional (3D) bronchial tree environment using just two-dimensional (2D) images, visual cues and haptic feedback. Sound knowledge and understanding of tracheobronchial anatomy as well as ample training experience is mandatory for technical mastery. Although simulated modalities facilitate safe training for inexperienced operators, current commercial training models are expensive or deficient in anatomical accuracy, clinical fidelity and patient representation. The advent of Three-dimensional (3D) printing technology may resolve the current limitations with commercial simulators. The purpose of this report is to develop and test the novel multi-material three-dimensional (3D) printed airway models for bronchoscopy simulation.

Methods

Using material jetting 3D printing and polymer amalgamation, human airway models were created from anonymized human thoracic computed tomography images from three patients: one normal, a second with a tumour obstructing the right main bronchus and third with a goitre causing external tracheal compression. We validated their efficacy as airway trainers by expert bronchoscopists. Recruited study participants performed bronchoscopy on the 3D printed airway models and then completed a standardized evaluation questionnaire.

Results

The models are flexible, life size, anatomically accurate and patient specific. Five expert respiratory physicians participated in validation of the airway models. All the participants agreed that the models were suitable for training bronchoscopic anatomy and access. Participants suggested further refinement of colour and texture of the internal surface of the airways. Most respondents felt that the models are suitable simulators for tracheal pathology, have a learning value and recommend it to others for use in training.

Conclusion

Using material jetting 3D printing to create patient-specific anatomical models is a promising modality of simulation training. Our results support further evaluation of the printed airway model as a bronchoscopic trainer, and suggest that pathological airways may be simulated using this technique.

From CT scanning to 3D printing technology: a new method for the preoperative planning of a transcutaneous bone-conduction hearing device

SUMMARY

The aim of the present study was to assess the feasibility and utility of 3D printing technology in surgical planning of a transcutaneous bone-conduction hearing device (Bonebridge^®) (BB), focusing on the identification of the proper location and placement of the transducer. 3D printed (3DP) models of three human cadaveric temporal bones, previously submitted to CT scan, were created with the representation of a topographic bone thickness map and the sinus pathway on the outer surface. The 3DP model was used to detect the most suitable location for the BB. A 3DP transparent mask that faithfully reproduced the surface of both the temporal bone and the 3DP model was also developed to correctly transfer the designated BB area. The accuracy of the procedure was verified by CT scan: a radiological marker was used to evaluate the degree of correspondence of the transducer site between the 3DP model and the human temporal bone. The BB positioning was successfully performed on all human temporal bones, with no difficulties in finding the proper location of the transducer. A mean error of 0.13 mm was found when the transducer site of the 3DP model was compared to that of the human temporal bone. The employment of 3D printing technology in surgical planning of BB positioning showed feasible results. Further studies will be required to evaluate its clinical applicability.

Challenges in creating dissectible anatomical 3D prints for surgical teaching

Three-dimensional (3D) printing, or additive manufacturing, is now a widely used tool in pre-operative planning, surgical teaching and simulator training. However, 3D printing technology that produces models with accurate haptic feedback, biomechanics and visuals for the training surgeon is not currently available. Challenges and opportunities in creating such surgical models will be discussed in this review paper. Surgery requires proper tissue handling as well as knowledge of relevant anatomy. To prepare doctors properly, training models need to take into account the biomechanical properties of the anatomical structures that will be manipulated in any given operation. This review summarises and evaluates the current biomechanical literature as it relates to human tissues and correlates the impact of this knowledge on developing high fidelity 3D printed surgical training models. We conclude that, currently, a printer technology has not yet been developed which can replicate many of the critical qualities of human tissue. Advances in 3D printing technology will be required to allow the printing of multi-material products to achieve the mechanical properties required.

Development and evaluation of rhinoplasty spreader graft suture simulator for novice surgeons

OBJECTIVE

Surgical simulators aimed at mimicking elements of rhinoplasty surgery, specifically those aimed at improving cartilage suturing, are not available. Here, we present a surgical simulator for spreader graft placement that uses cartilage rather than synthetic materials and gauge improvement using objective measures for suture placement accuracy, speed, and efficiency of hand motion.

METHODS

Twenty-two otolaryngologists in two groups (residents [10] and experts [12]) were instructed to secure the two spreader graft specimen into position with three mattress sutures on a nose model that used porcine septal cartilage as a proxy for the human counterpart. Hand motion was tracked using an electromagnetic position sensing device. The time required to complete the suture task, total hand displacement, cumulative number of hand motion direction changes, and accuracy of suture insertion were measured. These measurements were compared between the two cohort groups for construct validity. The subjects completed a survey to evaluate realism and value of the model.

RESULTS

The expert group had a lower mean time required to complete the task (P < 0.05), total hand displacement (P < 0.01), and number of hand motion direction changes (P < 0.001). No significant difference was observed between the two groups in suture precision measurement. The subjects agreed on the face validity and usefulness of the trainer.

CONCLUSIONS

Our study suggests that the simulator may be a useful tool to objectively gauge suturing efficiency. Devices such as this may be useful for developing skill with suturing cartilage tissue and potentially be used to assess resident acquisition of surgical skill.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:344-350, 2019.

New frontiers and emerging applications of 3D printing in ENT surgery: a systematic review of the literature

3D printing systems have revolutionised prototyping in the industrial field by lowering production time from days to hours and costs from thousands to just a few dollars. Today, 3D printers are no more confined to prototyping, but are increasingly employed in medical disciplines with fascinating results, even in many aspects of otorhinolaryngology. All publications on ENT surgery, sourced through updated electronic databases (PubMed, MEDLINE, EMBASE) and published up to March 2017, were examined according to PRISMA guidelines. Overall, 121 studies fulfilled specific inclusion criteria and were included in our systematic review. Studies were classified according to the specific field of application (otologic, rhinologic, head and neck) and area of interest (surgical and preclinical education, customised surgical planning, tissue engineering and implantable prosthesis). Technological aspects, clinical implications and limits of 3D printing processes are discussed focusing on current benefits and future perspectives.

A novel three-dimensional-printed paranasal sinus-skull base anatomical model

PURPOSE

A novel precision three-dimensional (3D)-printed paranasal sinus-skull base anatomical model was generated with a commercial grade desktop 3D printer. A specific page-turning pattern was employed in this model, to display the internal spatial structure of the paranasal sinus.

METHODS

The CT image data of paranasal sinus were imported into the Mimics software to construct a 3D digital paranasal sinus-skull base model. Then, the model was sliced in the coronal position and loaded into the 3D printer to print each slice of the paranasal sinus-skull base model at a ratio of 1:1 in size. Based on CT image data, nine senior doctors assessed the simulation and accuracy of the anatomical structure features of the paranasal sinus-skull base, and the advantages and educational value of the 3D printing model using a seven-point Likert scale.

RESULTS

A life-like 3D paranasal sinus-skull base structural model was successfully printed, with its internal spatial details clearly displayed. Nine senior doctors all thought that the profile of the printed anatomical structure was similar to that displayed by CT scan; however, the model provided more 3D spatial visual information. In addition, the model was considered to be of great value in the anatomy teaching and complicated surgery of the paranasal sinus-skull base, which had a material cost of only 3 dollars.

CONCLUSIONS

The 3D printed paranasal sinus-skull base model has 3D visual functions, which provides a novel tool for anatomical studies on paranasal sinus, resident training, pre-surgical education and surgical planning.

The precision and reliability evaluation of 3-dimensional printed damaged bone and prosthesis models by stereo lithography appearance

Recently, clinical application of 3D printed model was increasing. However, there was no systemic study for confirming the precision and reliability of 3D printed model. Some senior clinical doctors mistrusted its reliability in clinical application. The purpose of this study was to evaluate the precision and reliability of stereolithography appearance (SLA) 3D printed model.Some related parameters were selected to research the reliability of SLA 3D printed model. The computed tomography (CT) data of bone/prosthesis and model were collected and 3D reconstructed. Some anatomical parameters were measured and statistical analysis was performed; the intraclass correlation coefficient (ICC) was used to was used to evaluate the similarity between the model and real bone/prosthesis. the absolute difference (mm) and relative difference (%) were conducted. For prosthesis model, the 3-dimensional error was measured.There was no significant difference in the anatomical parameters except max height (MH) of long bone. All the ICCs were greater than 0.990. The maximum absolute and relative difference were 0.45 mm and 1.10%; The 3-dimensional error analysis showed that positive/minus distance were 0.273 mm/0.237 mm.The application of SLA 3D printed model in diagnosis and treatment process of complex orthopedic disease was reliable and precise.

An Assembled Prototype Multimaterial Three-Dimensional-Printed Model of the Neck for Computed Tomography- and Ultrasound-Guided Interventional Procedures

A low-cost, semirealistic, multimaterial prototype phantom of the neck was developed for computed tomography- and ultrasound-guided interventions, using three-dimensional (3D) printing with a variety of materials as well as through molding techniques. This dual-modality phantom can be used by trainees for practicing procedures and can also serve as a prototype for developing more complex and realistic 3D-printed models, particularly with the continued development and advancement in multimaterial 3D printing technologies.

Otologic Skills Training

This article presents a summary of the current simulation training for otologic skills. There is a wide variety of educational approaches, assessment tools, and simulators in use, including simple low-cost task trainers to complex computer-based virtual reality systems. A systematic approach to otologic skills training using adult learning theory concepts, such as repeated and distributed practice, self-directed learning, and mastery learning, is necessary for these educational interventions to be effective. Future directions include development of measures of performance to assess efficacy of simulation training interventions and, for complex procedures, improvement in fidelity based on educational goals.

3D printing and modelling of customized implants and surgical guides for non-human primates

BACKGROUND

Primate neurobiologists use chronically implanted devices such as pedestals for head stabilization and chambers to gain access to the brain and study its activity. Such implants are skull-mounted, and made from a hard, durable material, such as titanium.

NEW METHOD

Here, we present a low-cost method of creating customized 3D-printed cranial implants that are tailored to the anatomy of individual animals. We performed pre-surgical computed tomography (CT) and magnetic resonance (MR) scans to generate three-dimensional (3D) models of the skull and brain. We then used 3D modelling software to design implantable head posts, chambers, and a pedestal anchorage base, as well as craniotomy guides to aid us during surgery. Prototypes were made from plastic or resin, while implants were 3D-printed in titanium. The implants underwent post-processing and received a coating of osteocompatible material to promote bone integration.

RESULTS

Their tailored fit greatly facilitated surgical implantation, and eliminated the gap between the implant and the bone. To date, our implants remain robust and well-integrated with the skull.

COMPARISON WITH EXISTING METHOD(S)

Commercial-off-the-shelf solutions typically come with a uniform, flat base, preventing them from sitting flush against the curved surface of the skull. This leaves gaps for fluid and tissue ingress, increasing the risk of microbial infection and tissue inflammation, as well as implant loss.

CONCLUSIONS

The use of 3D printing technology enabled us to quickly and affordably create unique, complex designs, avoiding the constraints levied by traditional production methods, thereby boosting experimental success and improving the wellbeing of the animals.

Creating an Optimal 3D Printed Model for Temporal Bone Dissection Training

Objective:

Making a 3-dimensional (3D) temporal bone model is simple using a plaster powder bed and an inkjet printer. However, it is difficult to reproduce air-containing spaces and precise middle ear structures. The objective of this study was to overcome these problems and create a temporal bone model that would be useful both as a training tool and for preoperative simulation.

Methods:

Drainage holes were made to remove excess materials from air-containing spaces, ossicle ligaments were manually changed to bony structures, and small and/or soft tissue structures were colored differently while designing the 3D models. The outcomes were evaluated by 3 procedures: macroscopic and endoscopic inspection of the model, comparison of computed tomography (CT) images of the model to the original CT, and assessment of tactile sensation and reproducibility by 20 surgeons performing surgery on the model.

Results:

Macroscopic and endoscopic inspection, CT images, and assessment by surgeons were in agreement in terms of reproducibility of model structures. Most structures could be reproduced, but the stapes, tympanic sinus, and mastoid air cells were unsatisfactory. Perioperative tactile sensation of the model was excellent.

Conclusions:

Although this model still does not embody perfect reproducibility, it proved sufficiently practical for use in surgical training.

Computer-Aided Design and 3-Dimensional Printing for Costal Cartilage Simulation of Airway Graft Carving

Autologous cartilage grafting during open airway reconstruction is a complex skill instrumental to the success of the operation. Most trainees lack adequate opportunities to develop proficiency in this skill. We hypothesized that 3-dimensional (3D) printing and computer-aided design can be used to create a high-fidelity simulator for developing skills carving costal cartilage grafts for airway reconstruction. The rapid manufacturing and low cost of the simulator allow deployment in locations lacking expert instructors or cadaveric dissection, such as medical missions and Third World countries. In this blinded, prospective observational study, resident trainees completed a physical simulator exercise using a 3D-printed costal cartilage grafting tool. Participant assessment was performed using a Likert scale questionnaire, and airway grafts were assessed by a blinded expert surgeon. Most participants found this to be a very relevant training tool and highly rated the level of realism of the simulation tool.

The role of three-dimensional printed models of skull in anatomy education: a randomized controlled trail

Three-dimensional (3D) printed models represent educational tools of high quality compared with traditional teaching aids. Colored skull models were produced by 3D printing technology. A randomized controlled trial (RCT) was conducted to compare the learning efficiency of 3D printed skulls with that of cadaveric skulls and atlas. Seventy-nine medical students, who never studied anatomy, were randomized into three groups by drawing lots, using 3D printed skulls, cadaveric skulls, and atlas, respectively, to study the anatomical structures in skull through an introductory lecture and small group discussions. All students completed identical tests, which composed of a theory test and a lab test, before and after a lecture. Pre-test scores showed no differences between the three groups. In post-test, the 3D group was better than the other two groups in total score (cadaver: 29.5 [IQR: 25–33], 3D: 31.5 [IQR: 29–36], atlas: 27.75 [IQR: 24.125–32]; p = 0.044) and scores of lab test (cadaver: 14 [IQR: 10.5–18], 3D: 16.5 [IQR: 14.375–21.625], atlas: 14.5 [IQR: 10–18.125]; p = 0.049). Scores involving theory test, however, showed no difference between the three groups. In this RCT, an inexpensive, precise and rapidly-produced skull model had advantages in assisting anatomy study, especially in structure recognition, compared with traditional education materials.

Current Status of Simulation in Otolaryngology: A Systematic Review

OBJECTIVE

Otolaryngology is a highly technical and demanding specialty and the requirements for surgical trainees to acquire proficiency remains challenging. Simulation has been purported to be an effective tool in assisting with this. The aim of this systematic review is to identify the available otolaryngology simulators, their status of validation, and evaluation the level of evidence behind each training model and thereby establish a level of recommendation.

DESIGN

PubMed, ERIC, and Google Scholar databases were searched for articles that described otolaryngology simulators or training models between 1980 and April 2016. Any validation studies for simulators were also retrieved. Titles and abstracts were screened for relevance using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines. Level of evidence (LoE) and Level of recommendation (LoR) was awarded to each study and model, respectively.

RESULTS

A total of 70 studies were identified describing 64 simulators. Out of these, at least 54 simulators had 1 validation study. Simulators for the ear and temporal bone surgery were the most common (n = 32), followed by laryngeal and throat (n = 20) and endoscopic sinus surgery (n = 12). Face validity was evaluated by 29 studies, 20 attempted to show construct, 20 assessed content, 20 transfer, and only 2 assessed concurrent validity. Of the validation assessments, 2 were classified as Level 1b, 10 Level 2a, and 48 Level 2b. No simulators received the highest LoR, but 8 simulators received a LoR of 2.

CONCLUSIONS

Despite the lack of evidence in outcome studies and limited number of high-validity otolaryngology simulators, the role of simulation continues to grow across surgical specialties Hence, it is imperative that the simulators are of high validity and construct for trainees to practice and rehearse surgical skills to develop confidence.

Three-dimensional printing of a sinus pericranii model: technical note

BACKGROUND

Sinus pericranii (SP) is a rare venous malformation consisting of a single or multiple abnormal emissary veins communicating between intracranial sinuses and dilated epicranial veins. There is no consensus concerning diagnosis, management, and treatment of SP.

TECHNICAL NOTE

We report the case of a 4-month-old infant with a SP for whom we used a three-dimensional printed model in order to define the angioarchitecture, improve management, and help parents' understanding of this uncommon condition.

Surgical applications of three-dimensional printing: a review of the current literature & how to get started

Three dimensional (3D) printing involves a number of additive manufacturing techniques that are used to build structures from the ground up. This technology has been adapted to a wide range of surgical applications at an impressive rate. It has been used to print patient-specific anatomic models, implants, prosthetics, external fixators, splints, surgical instrumentation, and surgical cutting guides. The profound utility of this technology in surgery explains the exponential growth. It is important to learn how 3D printing has been used in surgery and how to potentially apply this technology. PubMed was searched for studies that addressed the clinical application of 3D printing in all surgical fields, yielding 442 results. Data was manually extracted from the 168 included studies. We found an exponential increase in studies addressing surgical applications for 3D printing since 2011, with the largest growth in craniofacial, oromaxillofacial, and cardiothoracic specialties. The pertinent considerations for getting started with 3D printing were identified and are discussed, including, software, printing techniques, printing materials, sterilization of printing materials, and cost and time requirements. Also, the diverse and increasing applications of 3D printing were recorded and are discussed. There is large array of potential applications for 3D printing. Decreasing cost and increasing ease of use are making this technology more available. Incorporating 3D printing into a surgical practice can be a rewarding process that yields impressive results.

Three-Dimensional Printing and Its Applications in Otorhinolaryngology-Head and Neck Surgery

Objective Three-dimensional (3D)-printing technology is being employed in a variety of medical and surgical specialties to improve patient care and advance resident physician training. As the costs of implementing 3D printing have declined, the use of this technology has expanded, especially within surgical specialties. This article explores the types of 3D printing available, highlights the benefits and drawbacks of each methodology, provides examples of how 3D printing has been applied within the field of otolaryngology-head and neck surgery, discusses future innovations, and explores the financial impact of these advances. Data Sources Articles were identified from PubMed and Ovid MEDLINE. Review Methods PubMed and Ovid Medline were queried for English articles published between 2011 and 2016, including a few articles prior to this time as relevant examples. Search terms included 3-dimensional printing, 3 D printing, otolaryngology, additive manufacturing, craniofacial, reconstruction, temporal bone, airway, sinus, cost, and anatomic models. Conclusions Three-dimensional printing has been used in recent years in otolaryngology for preoperative planning, education, prostheses, grafting, and reconstruction. Emerging technologies include the printing of tissue scaffolds for the auricle and nose, more realistic training models, and personalized implantable medical devices. Implications for Practice After the up-front costs of 3D printing are accounted for, its utilization in surgical models, patient-specific implants, and custom instruments can reduce operating room time and thus decrease costs. Educational and training models provide an opportunity to better visualize anomalies, practice surgical technique, predict problems that might arise, and improve quality by reducing mistakes.

[Simulation in surgical training]

BACKGROUND

Patient safety during operations hinges on the surgeon's skills and abilities. However, surgical training has come under a variety of restrictions. To acquire dexterity with decreasingly "simple" cases, within the legislative time constraints and increasing expectations for surgical results is the future challenge.

OBJECTIVES

Are there alternatives to traditional master-apprentice learning?

MATERIALS AND METHODS

A literature review and analysis of the development, implementation, and evaluation of surgical simulation are presented.

RESULTS

Simulation, using a variety of methods, most important physical and virtual (computer-generated) models, provides a safe environment to practice basic and advanced skills without endangering patients. These environments have specific strengths and weaknesses.

CONCLUSIONS

Simulations can only serve to decrease the slope of learning curves, but cannot be a substitute for the real situation. Thus, they have to be an integral part of a comprehensive training curriculum. Our surgical societies have to take up that challenge to ensure the training of future generations.

Current Applications and Future Perspectives of the Use of 3D Printing in Anatomical Training and Neurosurgery

3D printing is a form of rapid prototyping technology, which has led to innovative new applications in biomedicine. It facilitates the production of highly accurate three dimensional objects from substrate materials. The inherent accuracy and other properties of 3D printing have allowed it to have exciting applications in anatomy education and surgery, with the specialty of neurosurgery having benefited particularly well. This article presents the findings of a literature review of the Pubmed and Web of Science databases investigating the applications of 3D printing in anatomy and surgical education, and neurosurgery. A number of applications within these fields were found, with many significantly improving the quality of anatomy and surgical education, and the practice of neurosurgery. They also offered advantages over existing approaches and practices. It is envisaged that the number of useful applications will rise in the coming years, particularly as the costs of this technology decrease and its uptake rises.

Preoperative preparation for otologic surgery: temporal bone simulation

PURPOSE OF REVIEW

The field of temporal bone simulation (TBS) has largely focused on the development and validation of simulators as training and assessment tools. As technology has progressed over the years, researchers have, however, envisioned new clinical applications for simulators extending to preoperative surgical planning and case rehearsal. The purpose of this article was to review the current state of the art in TBS and to highlight recent advancements in the field. Because of space limitations, we will limit our discussion to computer-based virtual reality simulators.

RECENT FINDINGS

A review of the recent literature on TBS revealed very limited application of virtual reality simulators for preoperative preparation. Current evidence suggests limitations in fidelity preclude successful patient-specific case rehearsal using virtual reality simulation. Further investigation and clinical evaluation are required to validate its use outside of training and skill assessment.

SUMMARY

This article provides an overview of the current use of virtual reality simulators with emphasis on preoperative planning. We evaluate the limitations of the technology, and discuss potential areas of improvement for the future. More studies are necessary to assess the value of virtual reality simulation for preoperative preparation.

A Novel Temporal Bone Simulation Model Using 3D Printing Techniques

HYPOTHESIS

An inexpensive temporal bone model for use in a temporal bone dissection laboratory setting can be made using a commercially available, consumer-grade 3D printer.

BACKGROUND

Several models for a simulated temporal bone have been described but use commercial-grade printers and materials to produce these models. The goal of this project was to produce a plastic simulated temporal bone on an inexpensive 3D printer that recreates the visual and haptic experience associated with drilling a human temporal bone.

METHODS

Images from a high-resolution CT of a normal temporal bone were converted into stereolithography files via commercially available software, with image conversion and print settings adjusted to achieve optimal print quality. The temporal bone model was printed using acrylonitrile butadiene styrene (ABS) plastic filament on a MakerBot 2x 3D printer. Simulated temporal bones were drilled by seven expert temporal bone surgeons, assessing the fidelity of the model as compared with a human cadaveric temporal bone. Using a four-point scale, the simulated bones were assessed for haptic experience and recreation of the temporal bone anatomy.

RESULTS

The created model was felt to be an accurate representation of a human temporal bone. All raters felt strongly this would be a good training model for junior residents or to simulate difficult surgical anatomy. Material cost for each model was $1.92.

CONCLUSIONS

A realistic, inexpensive, and easily reproducible temporal bone model can be created on a consumer-grade desktop 3D printer.

Training for Skull Base Surgery with a Colored Temporal Bone Model Created by Three-Dimensional Printing Technology

OBJECTIVE

A 3-dimensional temporal bone model for skull base surgical training was reconstructed via the use of a selective laser sintering technique, which is one of the 3-dimensional printing technologies.

METHODS

The temporal bone model was created in 2 pieces to remove powder material in the mastoid air cells and to place dye into the semicircular canal and the Fallopian canal.

RESULTS

The powder material was minimal, and the decisive structures were identified in color.

CONCLUSIONS

This artificial model will pave the way to a "new era" in surgical training and medical education.

A review of simulation platforms in surgery of the temporal bone

BACKGROUND

Surgery of the temporal bone is a high-risk activity in an anatomically complex area. Simulation enables rehearsal of such surgery. The traditional simulation platform is the cadaveric temporal bone, but in recent years other simulation platforms have been created, including plastic and virtual reality platforms.

OBJECTIVE OF REVIEW

To undertake a review of simulation platforms for temporal bone surgery, specifically assessing their educational value in terms of validity and in enabling transition to surgery.

TYPE OF REVIEW

Systematic qualitative review.

SEARCH STRATEGY

Search of the Pubmed, CINAHL, BEI and ERIC databases.

EVALUATION METHOD

Assessment of reported outcomes in terms of educational value.

RESULTS

A total of 49 articles were included, covering cadaveric, animal, plastic and virtual simulation platforms. Cadaveric simulation is highly rated as an educational tool, but there may be a ceiling effect on educational outcomes after drilling 8-10 temporal bones. Animal models show significant anatomical variation from man. Plastic temporal bone models offer much potential, but at present lack sufficient anatomical or haptic validity. Similarly, virtual reality platforms lack sufficient anatomical or haptic validity, but with technological improvements they are advancing rapidly.

CONCLUSIONS

At present, cadaveric simulation remains the best platform for training in temporal bone surgery. Technological advances enabling improved materials or modelling mean that in the future plastic or virtual platforms may become comparable to cadaveric platforms, and also offer additional functionality including patient-specific simulation from CT data.

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.

Pre-operative simulation of pediatric mastoid surgery with 3D-printed temporal bone models

OBJECTIVES

As the process of additive manufacturing, or three-dimensional (3D) printing, has become more practical and affordable, a number of applications for the technology in the field of pediatric otolaryngology have been considered. One area of promise is temporal bone surgical simulation. Having previously developed a model for temporal bone surgical training using 3D printing, we sought to produce a patient-specific model for pre-operative simulation in pediatric otologic surgery. Our hypothesis was that the creation and pre-operative dissection of such a model was possible, and would demonstrate potential benefits in cases of abnormal temporal bone anatomy.

METHODS

In the case presented, an 11-year-old boy underwent a planned canal-wall-down (CWD) tympano-mastoidectomy for recurrent cholesteatoma preceded by a pre-operative surgical simulation using 3D-printed models of the temporal bone. The models were based on the child's pre-operative clinical CT scan and printed using multiple materials to simulate both bone and soft tissue structures. To help confirm the models as accurate representations of the child's anatomy, distances between various anatomic landmarks were measured and compared to the temporal bone CT scan and the 3D model.

RESULTS

The simulation allowed the surgical team to appreciate the child's unusual temporal bone anatomy as well as any challenges that might arise in the safety of the temporal bone laboratory, prior to actual surgery in the operating room (OR). There was minimal variability, in terms of absolute distance (mm) and relative distance (%), in measurements between anatomic landmarks obtained from the patient intra-operatively, the pre-operative CT scan and the 3D-printed models.

CONCLUSIONS

Accurate 3D temporal bone models can be rapidly produced based on clinical CT scans for pre-operative simulation of specific challenging otologic cases in children, potentially reducing medical errors and improving patient safety.