Moving Beyond the Temporal Bone Lab: Creating a Drilling Station in the Otolaryngology Clinic

With the advent of operable 3-dimensional (3D)-printed models, case preparation could occur outside of the cadaveric laboratory. The objective of this study was to design a mobile drilling station that can be used for surgical practice in a variety of clean workplaces. Using materials obtained from hardware stores and online retailers, a wheelable drilling station was constructed to mimic laboratory conditions while also being easily maneuverable into clinic rooms. The station houses the otologic drill, suction, and irrigation mechanisms, is height adjustable, and has a shielded workspace. The mobile drilling station was moved into a microscope-containing otolaryngology clinic room where faculty and trainees were asked to drill a pediatric 3D-printed temporal bone followed by completing an evaluation survey. This is the first mobile drilling station described in the literature and can be easily constructed, mobilized, and used in an otolaryngology clinic for dedicated surgical practice using 3D-printed models.

Developing a production workflow for 3D-printed temporal bone surgical simulators

INTRODUCTION

3D-printed temporal bone models enable the training and rehearsal of complex otological procedures. To date, there has been no consolidation of the literature regarding the developmental process of 3D-printed temporal bone models. A brief review of the current literature shows that many of the key surgical landmarks of the temporal bone are poorly represented in models. This study aims to propose a novel design and production workflow to produce high-fidelity 3D-printed temporal bone models for surgical simulation.

METHODS

Developmental phases for data extraction, 3D segmentation and Computer Aided Design (CAD), and fabrication are outlined. The design and fabrication considerations for key anatomical regions, such as the mastoid air cells and course of the facial nerve, are expounded on with the associated strategy and design methods employed. To validate the model, radiological measurements were compared and a senior otolaryngologist performed various surgical procedures on the model.

RESULTS

Measurements between the original scans and scans of the model demonstrate sub-millimetre accuracy of the model. Assessment by the senior otologist found that the model was satisfactory in simulating multiple surgical procedures.

CONCLUSION

This study offers a systematic method for creating accurate 3D-printed temporal bone models for surgical training. Results show high accuracy and effectiveness in simulating surgical procedures, promising improved training and patient outcomes.

A new 3D-printed temporal bone: 'the SAPIENS'-specific anatomical printed-3D-model in education and new surgical simulations

PURPOSE

Otology and neuro-otology surgeries pose significant challenges due to the intricate and variable anatomy of the temporal bone (TB), requiring extensive training. In the last years 3D-printed temporal bone models for otological dissection are becoming increasingly popular. In this study, we presented a new 3D-printed temporal bone model named 'SAPIENS', tailored for educational and surgical simulation purposes.

METHODS

The 'SAPIENS' model was a collaborative effort involving a multidisciplinary team, including radiologists, software engineers, ENT specialists, and 3D-printing experts. The development process spanned from June 2022 to October 2023 at the Department of Sense Organs, Sapienza University of Rome. Acquisition of human temporal bone images; temporal bone rendering; 3D-printing; post-printing phase; 3D-printed temporal bone model dissection and validation.

RESULTS

The 'SAPIENS' 3D-printed temporal bone model demonstrated a high level of anatomical accuracy, resembling the human temporal bone in both middle and inner ear anatomy. The questionnaire-based assessment by five experienced ENT surgeons yielded an average total score of 49.4 ± 1.8 out of 61, indicating a model highly similar to the human TB for both anatomy and dissection. Specific areas of excellence included external contour, sigmoid sinus contour, cortical mastoidectomy simulation, and its utility as a surgical practice simulator.

CONCLUSION

We have designed and developed a 3D model of the temporal bone that closely resembles the human temporal bone. This model enables the surgical dissection of the middle ear and mastoid with an excellent degree of similarity to the dissection performed on cadaveric temporal bones.

Unveiling the Intricacies of the Inner Ear Anatomy: Novel 3D-Printed Model for Detailed Visualization and Functional Demonstrations

OBJECTIVES

This research aimed to print realistically detailed and magnified three-dimensional models of the inner ear, specifically focusing on visualising its complex labyrinth structure and functioning simulation.

METHODS

Temporal bone computed-tomography data were imported into Mimics software to construct an initial three-dimensional inner-ear model. Subsequently, the model was amplified and printed with precision using a three-dimensional printer. Five senior attending physicians evaluated the printed model using a Likert scale to gauge its morphological accuracy, clinical applicability and anatomical teaching value.

RESULTS

The printed inner-ear model effectively demonstrated the intricate internal structure. All five physicians agreed that the model closely resembled the real inner ear in shape and structure, and simulated certain inner-ear functions. The model was considered highly valuable for understanding anatomical structure and disorders.

CONCLUSION

The three-dimensionally printed inner-ear model is highly simulated and provides a valuable visual tool for studying inner-ear anatomy and clinical teaching, benefiting otologists.

The 3-Dimensional Temporal Bone Dissection Manual: Operable Stepwise Models for Teaching Otologic Surgery

Deconstructing surgeries into steps and providing instructions with illustrations has been the staple of surgical textbooks for decades. However, it may be difficult for the novice surgeon to interpret 2-dimensional (2D) illustrations into 3D surgeries. The objective of this study is to create operable models that demonstrate the progression of surgery in 3D and allow for mastering the final steps of the operation first. Mastoidectomy was performed in a stepwise fashion to different end points on 5 identical 3D-printed temporal bone models to represent 5 major steps of the operation. The drilled models were computed tomography scanned and the subsequent images were used to create 3D model copies of each step. This is the first study to demonstrate that it is possible to create, scan, and copy stepwise, operable, patient-specific 3D-printed models, which the trainee can both reference as a 3D dissection guide and can operate on repeatedly and in any order.

Stereoscopic calibration for augmented reality visualization in microscopic surgery

PURPOSE

Middle and inner ear procedures target hearing loss, infections, and tumors of the temporal bone and lateral skull base. Despite the advances in surgical techniques, these procedures remain challenging due to limited haptic and visual feedback. Augmented reality (AR) may improve operative safety by allowing the 3D visualization of anatomical structures from preoperative computed tomography (CT) scans on real intraoperative microscope video feed. The purpose of this work was to develop a real-time CT-augmented stereo microscope system using camera calibration and electromagnetic (EM) tracking.

METHODS

A 3D printed and electromagnetically tracked calibration board was used to compute the intrinsic and extrinsic parameters of the surgical stereo microscope. These parameters were used to establish a transformation between the EM tracker coordinate system and the stereo microscope image space such that any tracked 3D point can be projected onto the left and right images of the microscope video stream. This allowed the augmentation of the microscope feed of a 3D printed temporal bone with its corresponding CT-derived virtual model. Finally, the calibration board was also used for evaluating the accuracy of the calibration.

RESULTS

We evaluated the accuracy of the system by calculating the registration error (RE) in 2D and 3D in a microsurgical laboratory setting. Our calibration workflow achieved a RE of 0.11 ± 0.06 mm in 2D and 0.98 ± 0.13 mm in 3D. In addition, we overlaid a 3D CT model on the microscope feed of a 3D resin printed model of a segmented temporal bone. The system exhibited small latency and good registration accuracy.

CONCLUSION

We present the calibration of an electromagnetically tracked surgical stereo microscope for augmented reality visualization. The calibration method achieved accuracy within a range suitable for otologic procedures. The AR process introduces enhanced visualization of the surgical field while allowing depth perception.

Use of patient-specific 3D printed models in pre-operative counseling for pediatric skull base surgery

OBJECTIVES

Pediatric cranial base pathology is anatomically complex and surgical treatment is oftentimes difficult to conceptualize for patients and their families. Three-dimensional (3D) models of the sinuses and cranial base have the potential to enhance patient understanding in numerous domains. Our objective is to assess the use of 3D models in pre-operative parental and patient counseling prior to endoscopic endonasal skull base surgery in the pediatric population.

METHODS

A survey was designed to assess parent and patient-perceived utility of 3D-printed models in surgical counseling prior to pediatric skull base surgery.

RESULTS

A total of 10 patients were included. The median age was 9 years (range = 5 months-15 years). Pathology included juvenile nasopharyngeal angiofibroma (JNA) (N = 4), fibrous dysplasia of the maxilla and sphenoid (N = 1), juvenile ossifying fibroma (N = 1), nasal dermoid (N = 2, one with intracranial extension), encephalocele (N = 1), and parapharyngeal ectopic glial tissue (N = 1). Nearly all parents agreed or strongly agreed that 3D printed models were helpful in explaining the patient's skull base pathology (N = 10), surgical plan (N = 10), and possible complications (N = 9). All parents strongly agreed that 3D models should be used routinely in pre-operative counseling for endoscopic endonasal surgery. According to a majority of parents, patients older than 4 years old found the models helpful in understanding their pathology (75%) and surgery (88%).

CONCLUSION

By allowing direct three-dimensional visualization of the target pathology, 3D models serve as a useful adjunct in enhancing patient comprehension of the pathologic entity, planned surgery, and potential complications prior to pediatric endoscopic endonasal skull base surgery.

3-D-Printed Models for Temporal Bone Training: A Validity Study

OBJECTIVE

3-D printing offers convenient and low-cost mastoidectomy training; nonetheless, training benefits using 3-D-printed temporal bones remain largely unexplored. In this study, we have collected validity evidence for a low-cost, 3-D-printed temporal bone for mastoidectomy training and established a credible pass/fail score for performance on the model.

STUDY DESIGN

A prospective educational study gathering validity evidence using Messick's validity framework.

SETTING

Seven Danish otorhinolaryngology training institutions.

PARTICIPANTS

Eighteen otorhinolaryngology residents (novices) and 11 experienced otosurgeons (experts).

INTERVENTION

Residents and experienced otosurgeons each performed two to three anatomical mastoidectomies on a low-cost, 3-D-printed temporal bone model produced in-house. After drilling, mastoidectomy performances were rated by three blinded experts using a 25-item modified Welling scale (WS).

MAIN OUTCOME MEASURE

Validity evidence using Messick's framework including reliability assessment applying both classical test theory and Generalizability theory.

RESULTS

Novices achieved a mean score of 13.9 points; experienced otosurgeons achieved 23.2 points. Using the contrasting groups method, we established a 21/25-point pass/fail level. The Generalizability coefficient was 0.91, and 75% of the score variance was attributable to participant performance, indicating a high level of assessment reliability. Subsequent D studies revealed that two raters rating one performance or one rater rating two performances were sufficiently reliable for high-stakes assessment.

CONCLUSION

Validity evidence supports using a low-cost, 3-D-printed model for mastoidectomy training. The model can be printed in-house using consumer-grade 3-D printers and serves as an additional training tool in the temporal bone curriculum. For competency-based training, we established a cut-off score of 21 of 25 WS points using the contrasting groups method.

3D-printing a cost-effective model for mastoidectomy training

BACKGROUND

3D-printed temporal bone models can potentially provide a cost-effective alternative to cadaver surgery that can be manufactured locally at the training department. The objective of this study was to create a cost-effective 3D-printed model suitable for mastoidectomy training using entry level and commercially available print technologies, enabling individuals, without prior experience on 3D-printing, to manufacture their own models for basic temporal bone training.

METHODS

Expert technical professionals and an experienced otosurgeon identified the best material for replicating the temporal bone and created a cost-effective printing routine for the model using entry-level print technologies. Eleven participants at a temporal bone dissection course evaluated the model using a questionnaire.

RESULTS

The 3D-printed temporal bone model was printed using a material extrusion 3D-printer with a heat resistant filament, reducing melting during drilling. After printing, a few simple post-processing steps were designed to replicate the dura, sigmoid sinus and facial nerve. Modifying the 3D-printer by installing a direct-drive and ruby nozzle resulted in more successful prints and less need for maintenance. Upon evaluation by otorhinolaryngology trainees, unanimous feedback was that the model provided a good introduction to the mastoidectomy procedure, and supplementing practice to cadaveric temporal bones.

CONCLUSION

In-house production of a cost-effective 3D-printed model for temporal bone training is feasible and enables training institutions to manufacture their own models. Further, this work demonstrates the feasibility of creating new temporal bone models with anatomical variation to provide ample training opportunity.

Validation of a three-dimensional printed pediatric middle ear model for endoscopic surgery training

Objective

The purpose of this study is to assess the anatomical appropriateness of a three-dimensional (3D) printed pediatric middle ear model with a replaceable middle ear unit as an endoscopic ear surgery (EES) simulator.

Methods

Single-blinded, prospective, proof-of-concept study conducted in a simulation operative suite. A simulator was developed through segmentation of source images and multi-material 3D printing. Subjects were asked to point to seven anatomical sites before and after a short anatomy presentation of a human middle ear photograph. They also filled out a survey about the feasibility of the model. Outcome variables included survey scores, pre-anatomy lesson (PreAL) and post-anatomy lesson (PostAL) quiz scores.

Results

There were 24 participants (19 residents, 1 fellow, and 4 attendings), none with self-reported proficiency in EES. The PreAL mean score was 4.42 and PostAL quiz mean score was 5.32 (average improvement of 43% [CI = 17%-70%]; p = .003). The higher the level of training, the higher the PreAL scores (0.55 points per year of training; p = .004). The subspecialty (otology, other, in-training) was also associated with the PreAL scores (p = .004). Total survey score means were 22.8 (out of 30).

Conclusion

The results of our study suggest that our model has adequate anatomical high fidelity to mimic a real, pediatric temporal bone for EES. As 3D printing technologies continue to advance, the quality of ear models has the potential to provide improved surgical training for pediatric EES.

Level of Evidence

4.

Systematic review and meta-analysis of 3D-printing in otolaryngology education

INTRODUCTION

Three-dimensional (3D) printing has received increased attention in recent years and has many applications. In the field of otolaryngology surgery, 3D-printed models have shown potential educational value and a high fidelity to actual tissues. This provides an opportunity for trainees to gain additional exposure, especially as conventional educational tools, such as cadavers, are expensive and in limited supply. The purpose of this study was to perform a meta-analysis of the uses of 3D-printing in otolaryngology education. The primary outcomes of investigation were surgical utility, anatomical similarity, and educational value of 3D-printed models. Secondary outcomes of interest included country of implementation, 3D-printer materials and costs, types of surgical simulators, and the levels of training of participants.

METHODS

MEDLINE, Embase, Web of Science, Google Scholar and previous reviews were searched from inception until June 2021 for eligible articles. Title, abstract, and data extraction were performed in duplicate. Data were analyzed using random-effects models. The National Institute of Health Quality Assessment Tool was used to rate the quality of the evidence.

RESULTS

A total of 570 abstracts were identified and screened by 2 independent reviewers. Of the 274 articles reviewed in full text, 46 articles met the study criteria and were included in the meta-analysis. Surgical skill utility was reported in 42 studies (563 participants) and had a high degree of acceptance (84.8%, 95% CI: 81.1%-88.4%). The anatomical similarity was reported in 39 studies (484 participants) and was received positively at 80.6% (95% CI: 77.0%-84.2%). Educational value was described in 36 studies (93 participants) and had the highest approval rating by participants at 90.04% (87.20%-92.88%). A subgroup analysis by year of publication demonstrated that studies published after 2015 had higher ratings across all outcomes compared to those published prior to 2015.

CONCLUSION

This study found that 3D-printing interventions in otolaryngology demonstrated surgical, anatomical, and educational value. In addition, the approval ratings of 3D-printed models indicate a positive trend over time. Future educational programs may consider implementing 3D-printing on a larger scale within the medical curriculum to enhance exposure to otolaryngology.

A simple and convenient 3D printed temporal bone model for drilling simulating surgery

BACKGROUND

It is still far away from most of us in that it requires complex 3D modeling.

AIMS/OBJECTIVES

To investigate a more precision, simple, convenient and economical three-dimensional (3D) printed temporal bone model printed by a commercial desktop 3D printer, which can be widely promoted and applied in the training of beginners in otology.

MATERIAL AND METHODS

The CT data of the temporal bone were imported into Mimics to construct a 3D digital model of the temporal bone. After loaded into a high-precision 3D printer, a high-precision temporal bone model was printed at a scale of 1:1. Then, the model was evaluated by 5 senior attending physicians, including its morphological accuracy, simulation about surgery, advantages and educational value, using the 7-point Likert scale.

RESULTS

A life-like temporal bone model was successfully printed out. Five senior attending physicians all thought that the printed model was similar to the natural temporal bone in physical properties and the haptic sensation of bone drilling, and was accurate, simple, convenient and effective. In addition, the model was considered to be of high application value in the teaching of temporal bone anatomy and surgery simulation, which had a material cost of only 3 dollars.

CONCLUSIONS

The high-precision 3D printed temporal bone model is highly similar to the natural temporal bone, and can be conveniently and effectively used in the training of simulating temporal bone surgery for beginners in otology. Its production is simple and economical, so it can be popularized on a large scale.

Effect of 3D-Printed Models on Cadaveric Dissection in Temporal Bone Training

Objective

Mastoidectomy is a cornerstone in the surgical management of middle and inner ear diseases. Unfortunately, training is challenged by insufficient access to human cadavers. Three-dimensional (3D) printing of temporal bones could alleviate this problem, but evidence on their educational effectiveness is lacking. It is largely unknown whether training on 3D-printed temporal bones improves mastoidectomy performance, including on cadavers, and how this training compares with virtual reality (VR) simulation. To address this knowledge gap, this study investigated whether training on 3D-printed temporal bones improves cadaveric dissection performance, and it compared this training with the already-established VR simulation.

Study Design

Prospective cohort study of an educational intervention.

Setting

Tertiary university hospital, cadaver dissection laboratory, and simulation center in Copenhagen, Denmark.

Methods

Eighteen otorhinolaryngology residents (intervention) attending the national temporal bone dissection course received 3 hours of mastoidectomy training on 3D-printed temporal bones. Posttraining cadaver mastoidectomy performances were rated by 3 experts using a validated assessment tool and compared with those of 66 previous course participants (control) who had received time-equivalent VR training prior to dissection.

Results

The intervention cohort outperformed the controls during cadaver dissection by 29% (P < .001); their performances were largely similar across training modalities but remained at a modest level (~50% of the maximum score).

Conclusion

Mastoidectomy skills improved from training on 3D-printed temporal bone and seemingly more so than on time-equivalent VR simulation. Importantly, these skills transferred to cadaveric dissection. Training on 3D-printed temporal bones can effectively supplement cadaver training when learning mastoidectomy.

3D-4K exoscope-assisted temporal bone dissection: a new frontier in surgical training

PURPOSE

To assess if 3D-4K exoscope is a valuable tool for temporal bone dissection and to evaluate its teaching potential.

METHODS

Six consecutive 3D-4K-exoscope-assisted cortical mastoidectomies were performed by a novice, an intermediate and an expert surgeon (two dissections each). All dissections were entirely recorded and later evaluated independently by three other experienced surgeons. The dissection end-product was evaluated according to the Melbourne Mastoidectomy Scale (MMS). Paired t test was used to assess whether novice and intermediate surgeons have a score improvement in the second dissection compared to the first one. Surgeons' interactions, depth effect, and 3D impression were also assessed to perform a subjective analysis.

RESULTS

Mean MMS scores for the novice, intermediate and expert surgeon were 11.3 ± 2.8, 13.8 ± 3.9 and 19 ± 1.3, respectively. Paired t test demonstrated a statically significant improvement between the first and the second dissection both for the novice and the intermediate surgeon (+ 4.7 and + 7 points; p = 0.0002). A high-quality magnification of the temporal bone was obtained, allowing the expert surgeon to identify all the anatomical structures without injuring them. The exoscope was capable of providing a high involvement in the dissections with very effective interactions between the expert surgeon and the trainees, that had access to the same surgical field view.

CONCLUSION

3D-4K-exoscope resulted adequate for a safe and effective mastoidectomy and showed a high potential for training and educational purposes. It can represent a valid option for surgical training of temporal bone dissection and a new interactive tool to understand the complex temporal bone anatomy.

Patient-specific Virtual Temporal Bone Simulation Based on Clinical Cone-beam Computed Tomography

OBJECTIVES

Patient-specific surgical simulation allows presurgical planning through three-dimensional (3D) visualization and virtual rehearsal. Virtual reality simulation for otologic surgery can be based on high-resolution cone-beam computed tomography (CBCT). This study aimed to evaluate clinicians' experience with patient-specific simulation of mastoid surgery.

METHODS

Prospective, multi-institutional study. Preoperative temporal bone CBCT scans of patients undergoing cochlear implantation (CI) were retrospectively obtained. Automated processing and segmentation routines were used. Otologic surgeons performed a complete mastoidectomy with facial recess approach on the patient-specific virtual cases in the institution's temporal bone simulator. Participants completed surveys regarding the perceived accuracy and utility of the simulation.

RESULTS

Twenty-two clinical CBCTs were obtained. Four attending otologic surgeons and 5 otolaryngology trainees enrolled in the study. The mean number of simulations completed by each participant was 16.5 (range 3-22). "Overall experience" and "usefulness for presurgical planning" were rated as "good," "very good," or "excellent" in 84.6% and 71.6% of the simulations, respectively. In 10.7% of simulations, the surgeon reported to have gained a significantly greater understanding of the patient's anatomy compared to standard imaging. Participants were able to better appreciate subtle anatomic findings after using the simulator for 60.4% of cases. Variable CBCT acquisition quality was the most reported limitation.

CONCLUSION

Patient-specific simulation using preoperative CBCT is feasible and may provide valuable insights prior to otologic surgery. Establishing a CBCT acquisition protocol that allows for consistent segmentation will be essential for reliable surgical simulation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1855-1862, 2021.

Operable, Low-Cost, High-Resolution, Patient-Specific 3D Printed Temporal Bones for Surgical Simulation and Evaluation

OBJECTIVES

Three-dimensional printed models created on a consumer level printer can be used to practice mastoidectomy and to discern mastoidectomy experience level. Current models in the literature for mastoidectomy are limited by expense or operability. The aims of this study were (1) to investigate the utility of an inexpensive model for mastoidectomy and (2) to assess whether the model can be used as an evaluation tool to discern the experience level of the surgeon performing mastoidectomy.

METHODS

Three-dimensional printed temporal bone models from the CT scan of a 7-year old patient were created using a consumer-level stereolithography 3D printer for a raw material cost of $10 each. Mastoidectomy with facial recess approach was performed by 4 PGY-2 residents, 4 PGY-5 residents, and 4 attending surgeons on the models who then filled out an evaluation. The drilled models were collected and then graded in a blinded fashion by 6 attending otolaryngologists.

RESULTS

Both residents and faculty felt the model was useful for training (mean score 4.7 out of 5; range: 4-5) and case preparation (mean score: 4.3; range: 3-5). Grading of the drilled models revealed significant differences between junior resident, senior resident, and attending surgeon scores (P = .012) with moderate to excellent interrater agreement (ICC = 0.882).

CONCLUSION

The described operable model that is patient-specific was rated favorably for pediatric mastoidectomy case preparation and training by residents and faculty. The model may be used to differentiate between experience levels and has promise for use in formative and summative evaluations.