3D Rapid Prototyping for Otolaryngology-Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling

Multidisciplinary Advanced Surgical Planning for Slide Tracheoplasty Using 3D-Printed Models

OBJECTIVE

The objective of this study was to develop and assess multidisciplinary advanced surgical planning (ASP) sessions using three dimensional (3D) printed models for cervicothoracic slide tracheoplasty (CST). We hypothesized that these sessions would improve surgeon confidence, streamline intraoperative planning, and highlight the utility of 3D modeling.

METHODS

3D-printed patient-specific trachea models were used in pre-operative ASP sessions consisting of a multidisciplinary case discussion and hands-on slide tracheoplasty simulation. Participants completed a survey rating realism, utility, impact on the final surgical plan, and pre- and post-session confidence. Statistical analysis was performed via Wilcoxon and Kruskal-Wallis tests.

RESULTS

Forty-eight surveys were collected across nine sessions and 27 different physicians. On a 5-point Likert scale, models were rated as "very realistic", "very useful" (both median of 4, IQR 3-4 and 4-5, respectively). Overall confidence increased by 1.4 points (+/- 0.7, p < 0.0001), with the largest change seen in those with minimal prior slide tracheoplasty experience (p = 0.005). Participants felt that the sessions "strongly" impacted their surgical plan or anticipated performance (median 4, IQR 4-5), regardless of training level or experience.

CONCLUSION

3D-printed patient-specific models were successfully implemented in ASP sessions for CST. Models were deemed very realistic and very useful by surgeons across multiple specialties and training levels. Surgical planning sessions also strongly impacted the final surgical plan and increased surgeon confidence for CST.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:3395-3401, 2024.

An update on simulation training in rhinology: a systematic review of evidence

BACKGROUND

Rhinological procedures demand a high degree of technical expertise and anatomical knowledge. Because of limited surgical opportunities, ethical considerations and the complexity of these procedures, simulation-based training has become increasingly important. This review aimed to evaluate the effectiveness of simulation models used in rhinology training.

METHODS

Searches were conducted on PubMed, Embase, Cochrane and Google Scholar for studies conducted between July 2012 and July 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis ('PRISMA') protocol defined a final list of articles. Each validated study was assigned a level of evidence and a level of recommendation based on the Oxford Centre of Evidence-Based Medicine classification.

RESULTS

Following exclusions, 42 articles were identified which encompassed six types of simulation models and 26 studies evaluated validity. The rhinological skills assessed included endoscopic sinus surgery (n = 28), skull base/cerebrospinal fluid leak repair (n = 14), management of epistaxis and/or sphenopalatine artery ligation (n = 8), and septoplasty and septorhinoplasty (n = 6). All studies reported the beneficial impact of their simulation models on trainee development.

CONCLUSION

Simulation training in rhinology is a valuable adjunct to traditional surgical education. Although evidence is of moderate quality, the findings highlight the importance of simulation-based training in rhinology training.

Application of 3D-Printed Model in the Cervical Spine Osteochondroma Surgery: A Case Report

A 73-year-old woman having a throat lump sensation and dysphagia for the past several months presented at our otorhinolaryngology outpatient clinic. A physical examination disclosed a protruding subepithelial mass over the right tonsil fossa. The mass was not tender and had no mucosal lesions or signs of active infection. Therefore, we arranged face and neck computed tomography scans, which reported a solitary osseous lesion over the anterior-right aspect of the C1-2 joint. Considering the rarity and unfamiliar anatomy of this disease, we built a 3D-printed model to assist with the surgical rehearsal of the procedure as well as with a preoperation discussion with the patient and her family. We arranged a combined Otolaryngology-Neurosurgery department approach after discussion with the neurosurgeon and successfully removed the lesion without sacrificing the overlying longus capitis muscle. The pathology examination revealed no evidence of malignancy. The final diagnosis was cervical spine solitary osteochondroma. The patient had a complete recovery of both oral cavity and normal swallowing function. No tumor recurred during the 3-year follow-up. On the basis of this case, in-house 3D-printing technology can offer a rapid, reliable model for an interdisciplinary team to use to enhance personalized presurgical planning, thus providing better patient engagement during hospitalization.

Training models and simulators for endoscopic transsphenoidal surgery: a systematic review

Endoscopic transsphenoidal surgery is a novel surgical technique requiring specific training. Different models and simulators have been recently suggested for it, but no systematic review is available. To provide a systematic and critical literature review and up-to-date description of the training models or simulators dedicated to endoscopic transsphenoidal surgery. A search was performed on PubMed and Scopus databases for articles published until February 2023; Google was also searched to document commercially available. For each model, the following features were recorded: training performed, tumor/arachnoid reproduction, assessment and validation, and cost. Of the 1199 retrieved articles, 101 were included in the final analysis. The described models can be subdivided into 5 major categories: (1) enhanced cadaveric heads; (2) animal models; (3) training artificial solutions, with increasing complexity (from "box-trainers" to multi-material, ct-based models); (4) training simulators, based on virtual or augmented reality; (5) Pre-operative planning models and simulators. Each available training model has specific advantages and limitations. Costs are high for cadaver-based solutions and vary significantly for the other solutions. Cheaper solutions seem useful only for the first stages of training. Most models do not provide a simulation of the sellar tumor, and a realistic simulation of the suprasellar arachnoid. Most artificial models do not provide a realistic and cost-efficient simulation of the most delicate and relatively common phase of surgery, i.e., tumor removal with arachnoid preservation; current research should optimize this to train future neurosurgical generations efficiently and safely.

Synthesis, Optical Properties, and In Vivo Biodistribution Performance of Polymethine Cyanine Fluorophores

Near-infrared (NIR) cyanine dyes showed enhanced properties for biomedical imaging. A systematic modification within the cyanine skeleton has been made through a facile design and synthetic route for optimal bioimaging. Herein, we report the synthesis of 11 NIR cyanine fluorophores and an investigation of their physicochemical properties, optical characteristics, photostability, and in vivo performance. All synthesized fluorophores absorb and emit within 610-817 nm in various solvents. These dyes also showed high molar extinction coefficients ranging from 27,000 to 270,000 cm-1 M-1, quantum yields 0.01 to 0.33, and molecular brightness 208-79,664 cm-1 M-1 in the tested solvents. Photostability data demonstrate that all tested fluorophores 28, 18, 20, 19, 25, and 24 are more photostable than the FDA-approved indocyanine green. In the biodistribution study, most compounds showed tissue-specific targeting to selectively accumulate in the adrenal glands, lymph nodes, or gallbladder while excreted to the hepatobiliary clearance route. Among the tested, compound 23 showed the best targetability to the bone marrow and lymph nodes. Since the safety of cyanine fluorophores is well established, rationally designed cyanine fluorophores established in the current study will expand an inventory of contrast agents for NIR imaging of not only normal tissues but also cancerous regions originating from these organs/tissues.

External Ventricular Drain Placement Teleproctoring Using a Novel Camera-Projector Navigation System: A Proof-of-Concept Study

BACKGROUND

Teleproctoring is an emerging method of bedside clinical teaching; however, its feasibility has been limited by the available technologies. The use of novel tools that incorporate 3-dimensional environmental information and feedback might offer better bedside teaching options for neurosurgical procedures, including external ventricular drain placement.

METHODS

A platform with a camera-projector system was used to proctor medical students on placing external ventricular drains on an anatomic model as a proof-of-concept study. Three-dimensional depth information of the model and surrounding environment was captured by the camera system and provided to the proctor who could provide projected annotations in a geometrically compensated manner onto the head model in real time. The medical students were randomized to identify Kocher's point on the anatomic model with or without the navigation system. The time required to identify Kocher's point and the accuracy were measured as a proxy for determining the effectiveness of the navigation proctoring system.

RESULTS

Twenty students were enrolled in the present study. Those in the experimental group identified Kocher's point an average of 130 seconds faster than did the control group (P < 0.001). The mean diagonal distance from Kocher's point was 8.0 ± 4.29 mm for the experimental group compared with 23.6 ± 21.98 mm for the control group (P = 0.053). Of the 10 students randomized to the camera-projector system arm, 70% were accurate to within 1 cm of Kocher's point compared with 40% of the control arm (P > 0.05).

CONCLUSIONS

Camera-projector systems for bedside procedure proctoring and navigation are a viable and valuable technology. We demonstrated its viability for external ventricular drain placement as a proof-of-concept. However, the versatility of this technology indicates that that it could be useful for a variety of even more complex neurosurgical procedures.

Model-assisted marsupialization of a large odontogenic keratocyst in the maxillofacial region using a multicolored 3D-printed model: A novel approach in surgical planning and teaching

3D printing can improve surgical planning and coordination between the healthcare team and serve as a valuable educational tool for students.

Abstract

Although the occurrence of odontogenic keratocysts (OKCs) in the maxillofacial region is not uncommon, their aggressive growth behavior requires advanced surgical techniques for minimal recurrence. The current case report describes the use of a multicolored 3D-printed model as an interactive visual aid for the surgical planning and management of an OKC treated with a minimally invasive surgical decompression technique. A cone-beam computed tomography scan of the patient showed a profound OKC involving the left side of the body of the mandible. A 3D printer was used to print a multicolor resin model of the patient's OKC lesion within the mandible. The printed model was successfully used as a planning tool for surgical intervention (i.e., marsupialization and enucleation) of the OKC. The model was also used as a handheld interactive visual aid for dental students, so they could more effectively understand the anatomical and surgical complexity of the case. The novel use of the multicolor 3D-printed model for treatment of this OKC improved visualization of the lesion during surgical planning and was a valuable teaching tool for educational discussion of this case.

Mental workload during endoscopic sinus surgery is associated with surgeons' skill levels

Introduction

Surgeons' mental workload during endoscopic sinus surgery (ESS) has not been fully evaluated. The assessment was challenging due to the great diversity of each patient's anatomy and the consequence variety of surgical difficulties. In this study, we examined the mental workload of surgeons with various surgical skill levels during ESS under the standardized condition provided by novel-designed 3D sinus models.

Materials and methods

Forty-seven participants performed a high-fidelity ESS simulation with 3D-printed sinus models. Surgeons' mental workload was assessed with the national aeronautics and space administration-task load index (NASA-TLX). Associations between the total and subscales score of NASA-TLX and surgical skill index, including the board certification status, the number of experienced ESS cases, and the objective structured assessment of technical skills (OSATS), were analyzed. In addition, 10 registrars repeated the simulation surgery, and their NASA-TLX score was compared before and after the repetitive training.

Results

The total NASA-TLX score was significantly associated with OSATS score (p = 0.0001). Primary component analysis classified the surgeons' mental burden into three different categories: (1) the skill-level-dependent factors (temporal demand, effort, and performance), (2) the skill-level-independent factors (mental and physical demand), and (3) frustration. After the repetitive training, the skill-level-dependent factors were alleviated (temporal demand; z = -2.3664, p = 0.0091, effort; z = -2.1704, p = 0.0346, and performance; z = -2.5992, p = 0.0017), the independent factors were increased (mental demand; z = -2.5992, p = 0.0023 and physical demand; z = -2.2509, p = 0.0213), and frustration did not change (p = 0.3625).

Conclusion

Some of the mental workload during ESS is associated with surgical skill level and alleviated with repetitive training. However, other aspects remain a burden or could worsen even when surgeons have gained surgical experience. Routine assessment of registrars' mental burdens would be necessary during surgical training to sustain their mental health.

Investigating the effectiveness of three-dimensionally printed anatomical models compared with plastinated human specimens in learning cardiac and neck anatomy: A randomized crossover study

Three-dimensional printing (3DP) technology has been increasingly applied in health profession education. Yet, 3DP anatomical models compared with the plastinated specimens as learning scaffolds are unclear. A randomized-controlled crossover study was used to evaluate the objective outcomes of 3DP models compared with the plastinated specimens through an introductory lecture and team study for learning relatively simple (cardiac) and complex (neck) anatomies. Given the novel multimaterial and multicolored 3DP models are replicas of the plastinated specimens, it is hypothesized that 3DP models have the same educational benefits to plastinated specimens. This study was conducted in two phases in which participants were randomly assigned to 3DP (n = 31) and plastinated cardiac groups (n = 32) in the first phase, whereas same groups (3DP, n = 15; plastinated, n = 18) used switched materials in the second phase for learning neck anatomy. The pretest, educational activities and posttest were conducted for each phase. Miller's framework was used to assess the cognitive outcomes. There was a significant improvement in students' baseline knowledge by 29.7% and 31.3% for Phase 1; 31.7% and 31.3% for Phase 2 plastinated and 3DP models. Posttest scores for cardiac (plastinated, 3DP mean ± SD: 57.0 ± 13.3 and 60.8 ± 13.6, P = 0.27) and neck (70.3 ± 15.6 and 68.3 ± 9.9, P = 0.68) phases showed no significant difference. In addition, no difference observed when cognitive domains compared for both cases. These results reflect that introductory lecture plus either the plastinated or 3DP modes were effective for learning cardiac and neck anatomy.

Repetitive simulation training with novel 3D ‐printed sinus models for functional endoscopic sinus surgeries

Background

The purpose of this study was to find a utility of a newly developed 3D‐printed sinus model and to evaluate the educational benefit of simulation training with the models for functional endoscopic sinus surgery (FESS).

Material and methods

Forty‐seven otolaryngologists were categorized as experts (board‐certified physicians with ≥200 experiences of FESS, n = 9), intermediates (board‐certified physicians with <200 experiences of FESS, n = 19), and novices (registrars, n = 19). They performed FESS simulation training on 3D‐printed models manufactured from DICOM images of computed tomography (CT) scan of real patients. Their surgical performance was assessed with the objective structured assessment of technical skills (OSATS) score and dissection quality evaluated radiologically with a postdissection CT scan. First we evaluated the face, content, and constructive values. Second we evaluated the educational benefit of the training. Ten novices underwent training (training group) and their outcomes were compared to the remaining novices without training (control group). The training group performed cadaveric FESS surgeries before and after the repetitive training.

Results

The feedback from experts revealed high face and content value of the 3D‐printed models. Experts, intermediates, and novices demonstrated statistical differences in their OSATS scores (74.7 ± 3.6, 58.3 ± 10.1, and 43.1 ± 11.1, respectively, p < .001), and dissection quality (81.1 ± 13.1, 93.7 ± 15.1, and 126.4 ± 25.2, respectively, p < .001). The training group improved their OSATS score (41.1 ± 8.0 to 61.1 ± 6.9, p < .001) and dissection quality (122.1 ± 22.2 to 90.9 ± 10.3, p = .013), while the control group not. After training, 80% of novices with no prior FESS experiences completed surgeries on cadaver sinuses.

Conclusion

Repeated training using the models revealed an initial learning curve in novices, which was confirmed in cadaveric mock FESS surgeries.

Level of evidence

N/A

In Vitro Nasal Tissue Model for the Validation of Nasopharyngeal and Midturbinate Swabs for SARS-CoV-2 Testing

Large-scale population testing is a key tool to mitigate the spread of respiratory pathogens, such as the current COVID-19 pandemic, where swabs are used to collect samples in the upper airways (e.g., nasopharyngeal and midturbinate nasal cavities) for diagnostics. However, the high volume of supplies required to achieve large-scale population testing has posed unprecedented challenges for swab manufacturing and distribution, resulting in a global shortage that has heavily impacted testing capacity worldwide and prompted the development of new swabs suitable for large-scale production. Newly designed swabs require rigorous preclinical and clinical validation studies that are costly and time-consuming (i.e., months to years long); reducing the risks associated with swab validation is therefore paramount for their rapid deployment. To address these shortages, we developed a 3D-printed tissue model that mimics the nasopharyngeal and midturbinate nasal cavities, and we validated its use as a new tool to rapidly test swab performance. In addition to the nasal architecture, the tissue model mimics the soft nasal tissue with a silk-based sponge lining, and the physiological nasal fluid with asymptomatic and symptomatic viscosities of synthetic mucus. We performed several assays comparing standard flocked and injection-molded swabs. We quantified the swab pickup and release and determined the effect of viral load and mucus viscosity on swab efficacy by spiking the synthetic mucus with heat-inactivated SARS-CoV-2 virus. By molecular assay, we found that injected molded swabs performed similarly or superiorly in comparison to standard flocked swabs, and we underscored a viscosity-dependent difference in cycle threshold values between the asymptomatic and symptomatic mucuses for both swabs. To conclude, we developed an in vitro nasal tissue model that corroborated previous swab performance data from clinical studies; this model will provide to researchers a clinically relevant, reproducible, safe, and cost-effective validation tool for the rapid development of newly designed swabs.

Simulation training in endoscopic skull base surgery: A scoping review

Objective

Methods

Results

Conclusions

Development of a cadaveric head and neck cancer model and three-dimensional analysis of margins in surgical navigation-aided ablations

INTRODUCTION

The adequacy of the surgical resection is the main controllable variable that is in the hands of the surgical team. There exists an unmet need to increase the rate of negative margins, particularly in cancers invading the craniofacial area. The study aimed 1) at developing a gross tumor model to be utilized for research, educational, and training purposes and 2) establishing the 3-dimensional relationship between the outer surface of the surgical specimen and tumor surface and test the effect of guiding ablations on cadavers with surgical navigation (SN).

MATERIAL AND METHODS

Seven cadaver heads were employed to create 24 craniofacial tumor models. Simulation of tumor resections was performed by 8 surgeons. Fourteen and 10 resections were performed with and without SN-guidance, respectively. Gross specimens underwent computed tomography and 3-dimensional analysis through dedicated software. Task load was assessed through a validated questionnaire. Tumor model reliability was studied based on visual analogue scale rate by surgeons and radiologists.

RESULTS

SN reduced the rate of margin involvement, particularly by decreasing the percentage of the gross specimen outer surface involvement in areas uncovered by normal bony structures. The workload of SN-aided ablations was found to be medium-to-somewhat-high. Tumor model reliability was deemed satisfactory except for the extension to bony structures.

CONCLUSIONS

A gross tumor model for head and neck cancers involving the craniofacial area was developed and resulted satisfactorily reliable from both a surgical and radiologic standpoint. SN reduced the rate of margin involvement, particularly by improving delineation of bone-uncovered areas.

In Vitro Nasal Tissue Model for the Validation of Nasopharyngeal and Mid-turbinate Swabs for SARS-CoV-2 Testing

Large-scale population testing is a key tool to mitigate the spread of respiratory pathogens, as in the current COVID-19 pandemic, where swabs are used to collect samples in the upper airways (e.g. nasopharyngeal and mid-turbinate nasal cavities) for diagnostics. However, the high volume of supplies required to achieve large-scale population testing has posed unprecedented challenges for swab manufacturing and distribution, resulting in a global shortage that has heavily impacted testing capacity world-wide and prompted the development of new swabs suitable for large-scale production. Newly designed swabs require rigorous pre-clinical and clinical validation studies that are costly and time consuming ( i . e . months to years long); reducing the risks associated with swab validation is therefore paramount for their rapid deployment. To address these shortages, we developed a 3D-printed tissue model that mimics the nasopharyngeal and mid-turbinate nasal cavities, and we validated its use as a new tool to rapidly test swab performance. In addition to the nasal architecture, the tissue model mimics the soft nasal tissue with a silk-based sponge lining, and the physiological nasal fluid with asymptomatic and symptomatic viscosities of synthetic mucus. We performed several assays comparing standard flocked and injection-molded swabs. We quantified the swab pick-up and release, and determined the effect of viral load and mucus viscosity on swab efficacy by spiking the synthetic mucus with heat-inactivated SARS-CoV-2 virus. By molecular assays, we found that injected molded swabs performed similarly or superiorly in comparison to standard flocked swabs and we underscored a viscosity-dependent difference in cycle threshold values between the asymptomatic and symptomatic mucus for both swabs. To conclude, we developed an in vitro nasal tissue model, that corroborated previous swab performance data from clinical studies, with the potential of providing researchers with a clinically relevant, reproducible, safe, and cost-effective validation tool for the rapid development of newly designed swabs.

Remote Training of Functional Endoscopic Sinus Surgery With Advanced Manufactured 3D Sinus Models and a Telemedicine System

Objective: Traditionally, cadaveric courses have been an important tool in surgical education for Functional Endoscopic Sinus Surgery (FESS). The recent COVID-19 pandemic, however, has had a significant global impact on such courses due to its travel restrictions, social distancing regulations, and infection risk. Here, we report the world-first remote (Functional Endoscopic Sinus Surgery) FESS training course between Japan and Australia, utilizing novel 3D-printed sinus models. We examined the feasibility and educational effect of the course conducted entirely remotely with encrypted telemedicine software.

Methods: Three otolaryngologists in Hokkaido, Japan, were trained to perform frontal sinus dissections on novel 3D sinus models of increasing difficulty, by two rhinologists located in Adelaide, South Australia. The advanced manufactured sinus models were 3D printed from the Computed tomography (CT) scans of patients with chronic rhinosinusitis. Using Zoom and the Quintree telemedicine platform, the surgeons in Adelaide first lectured the Japanese surgeons on the Building Block Concept for a three Dimensional understanding of the frontal recess. They in real time directly supervised the surgeons as they planned and then performed the frontal sinus dissections. The Japanese surgeons were asked to complete a questionnaire pertaining to their experience and the time taken to perform the frontal dissection was recorded. The course was streamed to over 200 otolaryngologists worldwide.

Results: All dissectors completed five frontal sinusotomies. The time to identify the frontal sinus drainage pathway (FSDP) significantly reduced from 1,292 ± 672 to 321 ± 267 s (p = 0.02), despite an increase in the difficulty of the frontal recess anatomy. Image analysis revealed the volume of FSDP was improved (2.36 ± 0.00 to 9.70 ± 1.49 ml, p = 0.014). Questionnaires showed the course's general benefit was 95.47 ± 5.13 in dissectors and 89.24 ± 15.75 in audiences.

Conclusion: The combination of telemedicine software, web-conferencing technology, standardized 3D sinus models, and expert supervision, provides excellent training outcomes for surgeons in circumstances when classical surgical workshops cannot be realized.

Potential of Intraoperative 3D Photography and 3D Visualization in Breast Reconstruction

Although pre- and postoperative three-dimensional (3D) photography are well-established in breast reconstruction, intraoperative 3D photography is not. We demonstrate the process of intraoperative acquisition and visualization of 3D photographs for breast reconstruction and present clinicians' opinions about intraoperative visualization tools.

METHODS

Mastectomy specimens were scanned with a handheld 3D scanner during breast surgery. The 3D photographs were processed to compute morphological measurements of the specimen. Three visualization modalities (screen-based viewing, augmented reality viewing, and 3D printed models) were created to show different representations of the 3D photographs to plastic surgeons. We interviewed seven surgeons about the usefulness of the visualization methods.

RESULTS

The average time for intraoperative acquisition of 3D photographs of the mastectomy specimen was 4 minutes, 8 seconds ± 44 seconds. The average time for image processing to compute morphological measurements of the specimen was 54.26 ± 40.39 seconds. All of the interviewed surgeons would be more inclined to use intraoperative visualization if it displayed information that they are currently missing (eg, the target shape of the reconstructed breast mound). Additionally, the surgeons preferred high-fidelity visualization tools (such as 3D printing) that are easy-to-use and have minimal disruption to their current workflow.

CONCLUSIONS

This study demonstrates that 3D photographs can be collected intraoperatively within acceptable time limits, and quantitative measurements can be computed timely to be utilized within the same procedure. We also report surgeons' comments on usability of visualization methods and of measurements of the mastectomy specimen, which can be used to guide future surgical practice.

3D Printing-A Cutting Edge Technology for Treating Post-Infarction Patients

The increasing complexity of cardiovascular interventions requires advanced peri-procedural imaging and tailored treatment. Three-dimensional printing technology represents one of the most significant advances in the field of cardiac imaging, interventional cardiology or cardiovascular surgery. Patient-specific models may provide substantial information on intervention planning in complex cardiovascular diseases, and volumetric medical imaging from CT or MRI can be translated into patient-specific 3D models using advanced post-processing applications. 3D printing and additive manufacturing have a great variety of clinical applications targeting anatomy, implants and devices, assisting optimal interventional treatment and post-interventional evaluation. Although the 3D printing technology still lacks scientific evidence, its benefits have been shown in structural heart diseases as well as for treatment of complex arrhythmias and corrective surgery interventions. Recent development has enabled transformation of conventional 3D printing into complex 3D functional living tissues contributing to regenerative medicine through engineered bionic materials such hydrogels, cell suspensions or matrix components. This review aims to present the most recent clinical applications of 3D printing in cardiovascular medicine, highlighting also the potential for future development of this revolutionary technology in the medical field.

Three dimensional printed models of the airway for preoperative planning of open Laryngotracheal surgery in children: Surgeon's perception of utility

BACKGROUND

Preoperative planning of open laryngotracheal surgery is important for achieving good results. This study examines the surgeon's perception of the importance of using life size 3D printed models of the pediatric airway on surgical decision making.

METHODS

Life-size three-dimensional models of the upper airway were created based on CT images of children scheduled for laryngotracheal-reconstruction and cricotracheal resection with anastomosis. Five pediatric airway surgeons evaluated the three-dimensional models for determining the surgical approach, incision location and length, graft length, and need for single or double-stage surgery of seven children (median age 4.4 years, M:F ratio 4:3). They rated the importance of the three-dimensional model findings compared to the direct laryngoscopy videos and CT findings for each domain on a validated Likert scale of 1-5.

RESULTS

The mean rating for all domains was 3.6 ± 0.63 ("moderately important" to "very important"), and the median rating was 4 ("very important"). There was full agreement between raters for length of incision and length of graft. The between-rater agreement was 0.608 ("good") for surgical approach, 0.585 ("moderate") for incision location, and 0.429 ("moderate") for need for single- or two-stage surgery.

CONCLUSION

Patient-specific three-dimensional printed models of children's upper airways were scored by pediatric airway surgeons as being moderately to very important for preoperative planning of open laryngotracheal surgery. Large-scale, objective outcome studies are warranted to establish the reliability and efficiency of these models.

Pre-contoured reconstruction plate fabricated via three-dimensional printed bending support

A mandibular continuity defect can be repaired using either a prosthetic device or autogenous bone. A titanium reconstruction plate can be used with a localized or vascularized flap over the defect of the mandible. Unfortunately, the plate may fail due to plate exposure, screw loosening, fracture, or infection, and will need to be removed. Plate exposure though the skin or mucosa is one of the main reasons for failure. In the present work, the authors introduced a lingually positioned reconstruction plate fabricated via three-dimensional printed bending support. This custom reconstruction plate can avoid plate re-exposure as well as reduce surgical errors and operation time.

A Personalized 3D-Printed Model for Obtaining Informed Consent Process for Thyroid Surgery: A Randomized Clinical Study Using a Deep Learning Approach with Mesh-Type 3D Modeling

The aim of this study was to evaluate the usefulness of a personalized 3D-printed thyroid model that characterizes a patient's individual thyroid lesion. The randomized controlled prospective clinical trial (KCT0005069) was designed. Fifty-three of these patients undergoing thyroid surgery were randomly assigned to two groups: with or without a 3D-printed model of their thyroid lesion when obtaining informed consent. We used a U-Net-based deep learning architecture and a mesh-type 3D modeling technique to fabricate the personalized 3D model. The mean 3D printing time was 258.9 min, and the mean price for production was USD 4.23 for each patient. The size, location, and anatomical relationship of the tumor and thyroid gland could be effectively presented using the mesh-type 3D modeling technique. The group provided with personalized 3D-printed models showed significant improvement in all four categories (general knowledge, benefits and risks of surgery, and satisfaction; all p < 0.05). All patients received a personalized 3D model after surgery and found it helpful to understand the disease, operation, and possible complications and their overall satisfaction (all p < 0.05). In conclusion, the personalized 3D-printed thyroid model may be an effective tool for improving a patient's understanding and satisfaction during the informed consent process.

Image-guided surgery in otolaryngology: A review of current applications and future directions in head and neck surgery

Image-guided surgery (IGS) has become a widely adopted technology in otolaryngology. Since its introduction nearly three decades ago, IGS technology has developed rapidly and improved real-time intraoperative visualization for a diverse array of clinical indications. As usability, accessibility, and clinical experiences with IGS increase, its potential applications as an adjunct in many surgical procedures continue to expand. Here, we describe the basic components of IGS and review both the current state and future directions of IGS in otolaryngology, with attention to current challenges to its application in surgery of the nonrigid upper aerodigestive tract.

Visual and haptic perceptibility of 3D printed skeletal models in orthognathic surgery

OBJECTIVE

To assess the anatomical and tactile quality of 3D printed models derived from medical printers for application in orthognathic surgery.

METHODS

A CBCT-scan of an 18 years old female patient was acquired with NewTom VGi evo (NewTom, Verona, Italy). Thereafter, mandibular bone was segmented and isolated from the scan using Mimics inPrint 2.0 software (Materialise NV, Leuven, Belgium). Six printers with different technologies were utilized for printing skeletal models, which included stereolithography (ProX800, 3D Systems, Rock Hill, SC, USA), digital light processing (Perfactory 4 mini XL, Envisiontec, Dearborn, MI, USA), fused deposition modeling (uPrint SE, Stratasys, Eden Prairie, MI, US), colorjet (ProJet CJP 660Pro, 3D Systems, Rock Hill, SC, USA), multijet (Objet Connex 350, Stratasys, Eden Prairie, MN, USA) and selective laser sintering (EOSINT P700, EOS GmbH, Munich, Germany). A questionnaire was designed, where 22 maxillofacial residents scored whether the printed models were able to mimic bone color, texture and anatomy. Five maxillofacial surgeons performed bone cutting with screw insertion/removal to assess the tactile perceptibility.

RESULTS

In relation to texture and cortical and medullary anatomy replication, Perfactory 4 mini XL printer showed the highest mean score, whereas, Objet Connex 350 scored highest for color replication. The haptic feedback for cutting and screw insertion/removal varied for each printer, however, overall it was found to be highest for ProX800, whereas, EOSINT P700 was found to be least favorable.

CONCLUSIONS

The digital light processing based Perfactory 4 mini XL printer offered the most acceptable anatomical model, whereas, deficiencies existed for the replication of haptic feedback to that of real bone with each printer.

CLINICAL SIGNIFICANCE

The study outcomes provide pearls and pitfalls of 3D printed models utilizing various printers and technologies. There is a need for research on multi-material printing as such to improve the haptic feedback of skeletal models and render the models more human bone-like to improve surgical planning and clinical training.

Additive Manufacturing of Resected Oral and Oropharyngeal Tissue: A Pilot Study

Better visualization of tumor structure and orientation are needed in the postoperative setting. We aimed to assess the feasibility of a system in which oral and oropharyngeal tumors are resected, photographed, 3D modeled, and printed using additive manufacturing techniques. Three patients diagnosed with oral/oropharyngeal cancer were included. All patients underwent preoperative magnetic resonance imaging followed by resection. In the operating room (OR), the resected tissue block was photographed using a smartphone. Digital photos were imported into Agisoft Photoscan to produce a digital 3D model of the resected tissue. Physical models were then printed using binder jetting techniques. The aforementioned process was applied in pilot cases including carcinomas of the tongue and larynx. The number of photographs taken for each case ranged from 63 to 195. The printing time for the physical models ranged from 2 to 9 h, costs ranging from 25 to 141 EUR (28 to 161 USD). Digital photography may be used to additively manufacture models of resected oral/oropharyngeal tumors in an easy, accessible and efficient fashion. The model may be used in interdisciplinary discussion regarding postoperative care to improve understanding and collaboration, but further investigation in prospective studies is required.

Accuracy of 3-dimensional printing of dental casts: A proposal for quality standardization

STATEMENT OF PROBLEM

A digital workflow in fixed prosthodontics may use a 3D printer to obtain a cast for porcelain application. Standards exist that define the accuracy of traditional casts, but the accuracy requirements of 3D-printed casts have not been defined.

PURPOSE

The purpose of this retrospective study was to investigate how the accuracy of 3D-printed casts affected prosthesis fit and whether they correctly reproduced interproximal contacts.

MATERIAL AND METHODS

Copings with different die spacings were used to test different 3D-printed casts of the same dental arch. The accuracy of the 3D casts was assessed by imaging and comparing the resulting standard tessellation language (STL) files with the original through a matching software program. Accuracy scores were then correlated with a score measuring how well the copings fit the casts. The first data set was obtained from a patient receiving restoration of the 4 maxillary incisors. The teeth were prepared, the dental arch was imaged intraorally, and 10 resin casts were printed with four 3D printers. Two sets of 4 zirconia test copings were prepared, and 3 clinicians assessed their fit on each cast. A further set of casts was created from a second patient requiring prosthetic restoration for 5 adjacent teeth to assess whether undersizing affected the best fit of the copings on their dies.

RESULTS

The clinical scores and accuracy scores did not correlate. The results suggested that printed dies showing a certain degree of undersizing might provide a better fit than those showing better correspondence to the actual anatomic structure. The oversized dies were the worst. Only 7 of 17 casts being assessed were deemed suitable for veneering of the copings. The undersized casts tested clinically better than casts printed by using the same printer under standard settings.

CONCLUSIONS

This retrospective study indicated that 3D-printed casts that do not allow copings to fit appropriately usually show mean excess oversizing. Axially undersizing the printed dies on casts might allow a better fit of copings to be veneered.

3D-printed patient individualised models vs cadaveric models in an undergraduate oral and maxillofacial surgery curriculum: Comparison of student's perceptions

BACKGROUND

Recent advances in 3D printing technology have enabled the emergence of new educational and clinical tools for medical professionals. This study provides an exemplary description of the fabrication of 3D-printed individualised patient models and assesses their educational value compared to cadaveric models in oral and maxillofacial surgery.

METHODS

A single-stage, controlled cohort study was conducted within the context of a curricular course. A patient's CT scan was segmented into a stereolithographic model and then printed using a fused filament 3D printer. These individualised patient models were implemented and compared against cadaveric models in a curricular oral surgery hands-on course. Students evaluated both models using a validated questionnaire. Additionally, a cost analysis for both models was carried out. P-values were calculated using the Mann-Whitney U test.

RESULTS

Thirty-eight fourth-year dental students participated in the study. Overall, significant differences between the two models were found in the student assessment. Whilst the cadaveric models achieved better results in the haptic feedback of the soft tissue, the 3D-printed individualised patient models were regarded significantly more realistic with regard to the anatomical correctness, the degree of freedom of movement and the operative simulation. At 3.46 € (compared to 6.51 €), the 3D-printed patient individualised models were exceptionally cost-efficient.

CONCLUSIONS

3D-printed patient individualised models presented a realistic alternative to cadaveric models in the undergraduate training of operational skills in oral and maxillofacial surgery. Whilst the 3D-printed individualised patient models received positive feedback from students, some aspects of the model leave room for improvement.

3D printed bone models in oral and cranio-maxillofacial surgery: a systematic review

AIM

This systematic review aimed to evaluate the use of three-dimensional (3D) printed bone models for training, simulating and/or planning interventions in oral and cranio-maxillofacial surgery.

MATERIALS AND METHODS

A systematic search was conducted using PubMed® and SCOPUS® databases, up to March 10, 2019, by following the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) protocol. Study selection, quality assessment (modified Critical Appraisal Skills Program tool) and data extraction were performed by two independent reviewers. All original full papers written in English/French/Italian and dealing with the fabrication of 3D printed models of head bone structures, designed from 3D radiological data were included. Multiple parameters and data were investigated, such as author's purpose, data acquisition systems, printing technologies and materials, accuracy, haptic feedback, variations in treatment time, differences in clinical outcomes, costs, production time and cost-effectiveness.

RESULTS

Among the 1157 retrieved abstracts, only 69 met the inclusion criteria. 3D printed bone models were mainly used as training or simulation models for tumor removal, or bone reconstruction. Material jetting printers showed best performance but the highest cost. Stereolithographic, laser sintering and binder jetting printers allowed to create accurate models with adequate haptic feedback. The cheap fused deposition modeling printers exhibited satisfactory results for creating training models.

CONCLUSION

Patient-specific 3D printed models are known to be useful surgical and educational tools. Faced with the large diversity of software, printing technologies and materials, the clinical team should invest in a 3D printer specifically adapted to the final application.

Multimaterial and multicolor 3D-printed model in training of transnasal endoscopic surgery for pituitary adenoma

OBJECTIVE

The aim of the present study was to investigate the practical value of a multimaterial and multicolor 3D-printed model in anatomical teaching, surgical training, and preoperative planning of transnasal endoscopic surgery for pituitary adenoma.

METHODS

Multimodality neuroimaging data were obtained in a 42-year-old healthy male volunteer and a 40-year-old female patient with an invasive nonfunctional pituitary adenoma. Three 3D-printed models were produced: a monomaterial and monocolor model, a monomaterial and multicolor model, and a multimaterial and multicolor model. The effects on anatomical teaching and surgical training for exposing the vidian nerve were assessed by 12 residents, and the training effect was validated on cadavers. The practical values for preoperative planning were evaluated by 6 experienced neurosurgeons. All evaluations were based on 5-point Likert questionnaires.

RESULTS

The multimaterial and multicolor model was superior to the monomaterial models in surgical training for exposing the vidian nerve (Fisher test; p < 0.05). In addition, the multimaterial and multicolor model was superior to the monomaterial models in anatomical teaching and preoperative planning (Friedman test; p < 0.05).

CONCLUSIONS

Multimaterial and multicolor 3D printing technology makes it convenient and efficient to produce a practical model for simulating individualized and complex anatomical structures in the sellar region. Furthermore, the multimaterial model can provide a more realistic manipulative experience for surgical training and facilitate the preoperative planning.

WITHDRAWN: Simulation-based training in endoscopic endonasal surgery: Assessment of the cyrano simulator

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Human Inner-ear Malformation Types Captured in 3D

OBJECTIVES

Capture the human inner-ear malformation types in 3D by segmenting the inner-ear structures from clinical CT (computed tomography) and MR (magnetic resonance) image datasets. Volumetric analysis was done to find the variations in the volume of cochlear part alone from complete inner-ear followed by 3D printing from the 3D segmented models.

MATERIALS AND METHODS

Using 3D slicer freeware, the complete inner-ear structures were segmented from anonymized CT and MR image by setting a tight grey-scale threshold to avoid capturing unwanted structures followed by volumetric analysis of the cochlear part alone. 3D printing was done using Form labs desktop 3D printer.

RESULTS

We identified 2x normal anatomy (NA) cochlea, 1x enlarged vestibular aqueduct syndrome (EVAS), 3x incomplete partition (IP) type-I, 4x IP type-II, 3x IP type-III, 5x common cavity (CC) and 5x cochlear hypoplasia (CH). 3D segmented models along with the 3D printed models showed huge variation in size, shape and the anatomy among the image data-sets analyzed. Volumetric analysis showed that on average, volume of CC was above 150mm3, volume of CH fell below 80mm3, Volume of NA, EVAS and IP-I were all around 85-105mm3 whereas the volume of IP-II was around 50mm3.

CONCLUSION

Visualizing human inner-ear malformation types in 3D both as computer models and as 3D printed models is a whole-new experience as demonstrated in this study. The volumetric analysis showed a huge variation among the volume of cochlear part alone among the malformation types.

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.

Applications of three-dimensional printing in orbital diseases and disorders

PURPOSE OF REVIEW

To comprehensively review the applications of advanced three-dimensional printing technology in the management of orbital abnormalities.

RECENT FINDINGS

Three-dimensional printing has added value in the preoperative planning and manufacturing of patient-specific implants and surgical guides in the reconstruction of orbital trauma, congenital defects and tumor resection. In view of the costs and time, it is reserved as strategy for large and complex craniofacial cases, in particular those including the bony contour. There is anecdotal evidence of a benefit of three-dimensional printing in the manufacturing of prostheses for the exenterated and anophthalmic socket, and in the fabrication of patient-specific boluses, applicators and shielding devices for orbital radiation therapy. In addition, three-dimensional printed healthy and diseased orbits as phantom tangible models may augment the teaching and learning process of orbital surgery.

SUMMARY

Three-dimensional printing allows precision treatment tailored to the unique orbital anatomy of the patient. Advancement in technology and further research are required to support its wider use in orbital clinical practice.

Validation of Animal Models for Simulation Training in Pediatric Laryngotracheal Reconstruction

OBJECTIVES

To assess and compare the face (FV) and content validity (CV) of three ex vivo animal models for simulation training in pediatric laryngotracheal reconstruction (LTR).

METHODS

Feasibility of performing LTR was assessed on the head and neck of three different animals (lamb/suckling-pig/rabbit) and laryngeal dimensions and qualitative observations were recorded. A 19-item five-point Likert scale questionnaire was completed for each model to assess FV and CV. Data was prospectively collected and analyzed using descriptive and nonparametric statistics.

RESULTS

All three models were suitable for LTR simulation with laryngeal dimensions corresponding to 0-2 years (rabbit), 5-10 (pig) and >10 years (lamb model). Five trainees and five expert pediatric otolaryngologists performed LTR on each model. The overall median FV score was 5 for the lamb model (IQR 4-5), 3 for the rabbit (IQR 2-3), and 4 for the pig (IQR 4-4). The overall median CV score was 5 for the lamb (IQR 5-5), 2 for the rabbit (IQR 2-3), and 4 for the pig model (IQR 4-4). Comparison of the models demonstrated the lamb to be favored as the most realistic and practical model for simulation training in pediatric LTR, with both the lamb and the porcine model attaining validation thresholds.

CONCLUSION

Our study is the first comparative validation assessment of animal models for use in pediatric LTR simulation and it supports the use of ex vivo lamb and porcine models for use in LTR surgical skills training. The lamb model was the favored simulation model while the rabbit was considered inferior for simulation training in pediatric LTR.

LEVEL OF EVIDENCE

3b.

Three-Dimensional Printing: Current Use in Rhinology and Endoscopic Skull Base Surgery

Background

In the discipline of rhinology and endoscopic skull base surgery (ESBS), 3-dimensional (3D) printing has found meaningful application in areas including preoperative surgical planning as well as in surgical education. However, its scope of use may be limited due to the perception among surgeons that there exists a prohibitively high initial investment in resources and time to acquire the requisite technical expertise. Nevertheless, given the ever decreasing cost of advancing technology coupled with the need to understand the complex spatial relationships of the paranasal sinuses and skull base, the use of 3D printing in rhinology and ESBS is poised to blossom.

Objective

Help the reader identify current or potential future uses of 3D printing technology relevant to their rhinologic clinical or educational practice.

Methods

A review of published literature relating to 3D printing in rhinology and ESBS was performed.

Results

Results were reviewed and organized into 5 overarching categories including an overview of the 3D printing process as well as applications of 3D printing including (1) surgical planning, (2) custom prosthetics and implants, (3) patient education, and (4) surgical teaching and assessment.

Conclusion

In the discipline of rhinology and ESBS, 3D printing finds use in the areas of presurgical planning, patient education, prosthesis creation, and trainee education. As this technology moves forward, these products will be more broadly available to providers in the clinical and educational setting. The possible applications are vast and have great potential to positively impact surgical training, patient satisfaction, and most importantly, patient outcomes.

Physical Simulation Models in Oral and Maxillofacial Surgery: A New Concept in 3-Dimensional Modeling for Removal of Impacted Third Molars

A medical-grade computed tomography scan of a mandible was obtained. A DICOM (Digital Imaging and Communications in Medicine) series was exported in 1-mm slices and digitally 3-dimensionally reconstructed to create a stereolithography file. The mandible stereolithography file was digitally manipulated to create sites for simulated placement of third molar teeth and then 3-dimensionally printed in a plastic material. Third molar tooth models were coated in red box wax, simulating a ligament space, and then submerged into the mandible site using laboratory stone. A layer of GI-Mask (Coltene/Whaldent AG, Altstätten, Switzerland) was placed over the impacted third molar site for soft tissue simulation.

Haptic, Physical, and Web-Based Simulators: Are They Underused in Maxillofacial Surgery Training?

PURPOSE

Surgical residencies have increasingly incorporated both digital and mannequin simulation into their training programs. The aim of our review was to identify all digital and mannequin maxillofacial simulators available for education and training, highlight their benefit, and critically assess the evidence in support of these educational resources.

MATERIALS AND METHODS

We performed a comprehensive literature review of all peer-reviewed publications of digital and mannequin simulators that met the inclusion criteria, defined as any simulator used in education or training. All simulators used in surgical planning were excluded. Before the query, it was hypothesized that most studies would be descriptive in nature and supported by low levels of evidence. Literature search strategies included the use of multiple combinations of key search terms, review of titles and abstracts, and precise identification of the use of the simulator described. All statistics were descriptive.

RESULTS

The primary search yielded 259 results, from which 22 total simulators published on from 2001 to 2016 were identified using the inclusion and exclusion criteria: 10 virtual reality haptic-based simulators, 6 physical model simulators, and 6 Web-based simulators used for a variety of procedures such as dental skills, instrument handling, orthognathic surgery (Le Fort I osteotomy, vertical ramus osteotomy, bilateral sagittal split ramus osteotomy), genioplasty, bone grafting, sinus surgery, cleft lip repair, orbital floor repair, and oral biopsy. Only 9 formalized studies were completed; these were classified as low-level evidence-based cohort studies (Levels IV and V). All other simulator reports were descriptive in nature. There were no studies with high levels of evidence completed (Level I to III).

CONCLUSIONS

The results of this review suggest that, although seemingly beneficial to the trainee in maxillofacial surgery, simulation in education in this field is an underused commodity because of the significant lack of scientific and validated study designs reported on in the literature thus far. The maxillofacial and simulation communities would benefit from studies on utility and efficacy with higher levels of evidence.

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.

3D Printed Surgical Simulation Models as educational tool by maxillofacial surgeons

INTRODUCTION

The aim of this study was to evaluate whether inexpensive 3D models can be suitable to train surgical skills to dental students or oral and maxillofacial surgery residents. Furthermore, we wanted to know which of the most common filament materials, acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA), can better simulate human bone according to surgeons' subjective perceptions.

MATERIALS AND METHODS

Upper and lower jaw models were produced with common 3D desktop printers, ABS and PLA filament and silicon rubber for soft tissue simulation. Those models were given to 10 blinded, experienced maxillofacial surgeons to perform sinus lift and wisdom teeth extraction. Evaluation was made using a questionnaire.

RESULTS

Because of slightly different density and filament prices, each silicon-covered model costs between 1.40-1.60 USD (ABS) and 1.80-2.00 USD (PLA) based on 2017 material costs. Ten experienced raters took part in the study. All raters deemed the models suitable for surgical education. No significant differences between ABS and PLA were found, with both having distinct advantages.

CONCLUSION

The study demonstrated that 3D printing with inexpensive printing filaments is a promising method for training oral and maxillofacial surgery residents or dental students in selected surgical procedures. With a simple and cost-efficient manufacturing process, models of actual patient cases can be produced on a small scale, simulating many kinds of surgical procedures.

Optimization of 3D Print Material for the Recreation of Patient-Specific Temporal Bone Models

Objective:

Identify the 3D printed material that most accurately recreates the visual, tactile, and kinesthetic properties of human temporal bone

Subjects and Methods:

Fifteen study participants with an average of 3.6 years of postgraduate training and 56.5 temporal bone (TB) procedures participated. Each participant performed a mastoidectomy on human cadaveric TB and five 3D printed TBs of different materials. After drilling each unique material, participants completed surveys to assess each model’s appearance and physical likeness on a Likert scale from 0 to 10 (0 = poorly representative, 10 = completely life-like). The 3D models were acquired by computed tomography (CT) imaging and segmented using 3D Slicer software.

Results:

Polyethylene terephthalate (PETG) had the highest average survey response for haptic feedback (HF) and appearance, scoring 8.3 (SD = 1.7) and 7.6 (SD = 1.5), respectively. The remaining plastics scored as follows for HF and appearance: polylactic acid (PLA) averaged 7.4 and 7.6, acrylonitrile butadiene styrene (ABS) 7.1 and 7.2, polycarbonate (PC) 7.4 and 3.9, and nylon 5.6 and 6.7.

Conclusion:

A PETG 3D printed temporal bone models performed the best for realistic appearance and HF as compared with PLA, ABS, PC, and nylon. The PLA and ABS were reliable alternatives that also performed well with both measures.

Geometric and mechanical evaluation of 3D-printing materials for skull base anatomical education and endoscopic surgery simulation - A first step to create reliable customized simulators

INTRODUCTION

Endoscopic skull base surgery allows minimal invasive therapy through the nostrils to treat infectious or tumorous diseases. Surgical and anatomical education in this field is limited by the lack of validated training models in terms of geometric and mechanical accuracy. We choose to evaluate several consumer-grade materials to create a patient-specific 3D-printed skull base model for anatomical learning and surgical training.

METHODS

Four 3D-printed consumer-grade materials were compared to human cadaver bone: calcium sulfate hemihydrate (named Multicolor), polyamide, resin and polycarbonate. We compared the geometric accuracy, forces required to break thin walls of materials and forces required during drilling.

RESULTS

All materials had an acceptable global geometric accuracy (from 0.083mm to 0.203mm of global error). Local accuracy was better in polycarbonate (0.09mm) and polyamide (0.15mm) than in Multicolor (0.90mm) and resin (0.86mm). Resin and polyamide thin walls were not broken at 200N. Forces needed to break Multicolor thin walls were 1.6-3.5 times higher than in bone. For polycarbonate, forces applied were 1.6-2.5 times higher. Polycarbonate had a mode of fracture similar to the cadaver bone. Forces applied on materials during drilling followed a normal distribution except for the polyamide which was melted. Energy spent during drilling was respectively 1.6 and 2.6 times higher on bone than on PC and Multicolor.

CONCLUSION

Polycarbonate is a good substitute of human cadaver bone for skull base surgery simulation. Thanks to short lead times and reasonable production costs, patient-specific 3D printed models can be used in clinical practice for pre-operative training, improving patient safety.

3D printing materials and their use in medical education: a review of current technology and trends for the future

3D printing is a new technology in constant evolution. It has rapidly expanded and is now being used in health education. Patient-specific models with anatomical fidelity created from imaging dataset have the potential to significantly improve the knowledge and skills of a new generation of surgeons. This review outlines five technical steps required to complete a printed model: They include (1) selecting the anatomical area of interest, (2) the creation of the 3D geometry, (3) the optimisation of the file for the printing and the appropriate selection of (4) the 3D printer and (5) materials. All of these steps require time, expertise and money. A thorough understanding of educational needs is therefore essential in order to optimise educational value. At present, most of the available printing materials are rigid and therefore not optimum for flexibility and elasticity unlike biological tissue. We believe that the manipuation and tuning of material properties through the creation of composites and/or blending materials will eventually allow for the creation of patient-specific models which have both anatomical and tissue fidelity.