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.

Learning Curves in Directed Self-Regulated Virtual Reality Training of Mastoidectomy and the Role of Repetition and Motivation.

BACKGROUND: Mastoidectomy is a complex procedure which can be trained on human cadaveric temporal bones or simulation models. The number of repetitions offered in most training curricula is considerably less than what is normally required for motor skills acquisition in crafts or sports. Directed, self-regulated virtual reality simulation training may provide unlimited repetitions but the effect on learning of extended but unsupervised training is unknown. This study recorded extended learning curves of novices in virtual reality simulation mastoidectomy training. METHODS: Six medical students used the visible ear temporal bone simulator at home for 100 repetitions. Virtual temporal bones were later assessed by 2 blinded experts on a 26-point modified Welling Scale. RESULTS: Four participants completed 100 procedures each and 2 participants completed 50 procedures. Learning curves and plots of time demonstrated great variation: one participant improved gradually during the first 50 procedures and sustained a high performance; another participant achieved only 16 points after 50 procedures; a third participant demonstrated mediocre performances between 10 and 15 points but only used about 5 minutes per procedure. The remaining 3 participants achieved high but fluctuating scores with very limited time use per procedure. Their score per time exceeds the performance of experienced otosurgeons and suggests the use of save/restore gaming strategies to inflate their performance. CONCLUSION: Deliberate learners may reach proficiency in virtual reality simulation of mastoidectomy after 50 repetitions. However, even 100 repetitions cannot guarantee proficiency if motivation fails. Creative "gaming" behavior must be considered and opposed by motivation, supervision, testing, and certification.

Cellular voids in the pathogenesis of otosclerosis.

BACKGROUND: Otosclerosis is a common ear disease that causes fixation of the stapes and conductive hearing impairment. However, the pathogenesis of otosclerosis is still unknown. Otosclerosis could be associated with the unique bony environment found in the otic capsule. Normal bone remodelling is almost completely absent around the inner ear after birth allowing degenerative changes and dead osteocytes to accumulate. High levels of inner ear anti resorptive osteoprotegerin (OPG) is most likely responsible for this capsular configuration. Studies have demonstrated how osteocyte lifespan variation creates occasional clusters of dead osteocytes, so-called cellular voids, at otosclerotic predilection sites in the human otic capsule. These cellular voids have been suggested as possible starting points of otosclerosis. AIM: To describe the cellular viability in otosclerotic lesions and compare it to that of cellular voids. MATERIALS AND METHODS: The study was based on unbiased stereological quantifications in undecalcified human temporal bones with otosclerosis. RESULTS: Osteocyte viability was found to vary within the otosclerotic lesions. Furthermore, the results presented here illustrate that inactive otosclerotic lesions consist of mainly dead interstitial bone, much like cellular voids. CONCLUSIONS AND SIGNIFICANCE: Focal degeneration in the otic capsule may play an important role in the pathogenesis of otosclerosis.

Are Video Recordings Reliable for Assessing Surgical Performance? A Prospective Reliability Study Using Generalizability Theory.

INTRODUCTION: Reliability is pivotal in surgical skills assessment. Video-based assessment can be used for objective assessment without physical presence of assessors. However, its reliability for surgical assessments remains largely unexplored. In this study, we evaluated the reliability of video-based versus physical assessments of novices' surgical performances on human cadavers and 3D-printed models-an emerging simulation modality. METHODS: Eighteen otorhinolaryngology residents performed 2 to 3 mastoidectomies on a 3D-printed model and 1 procedure on a human cadaver. Performances were rated by 3 experts evaluating the final surgical result using a well-known assessment tool. Performances were rated both hands-on/physically and by video recordings. Interrater reliability and intrarater reliability were explored using κ statistics and the optimal number of raters and performances required in either assessment modality was determined using generalizability theory. RESULTS: Interrater reliability was moderate with a mean κ score of 0.58 (range 0.53-0.62) for video-based assessment and 0.60 (range, 0.55-0.69) for physical assessment. Video-based and physical assessments were equally reliable (G coefficient 0.85 vs. 0.80 for 3D-printed models and 0.86 vs 0.87 for cadaver dissections). The interaction between rater and assessment modality contributed to 8.1% to 9.1% of the estimated variance. For the 3D-printed models, 2 raters evaluating 2 video-recorded performances or 3 raters physically assessing 2 performances yielded sufficient reliability for high-stakes assessment (G coefficient >0.8). CONCLUSIONS: Video-based and physical assessments were equally reliable. Some raters were affected by changing from physical to video-based assessment; consequently, assessment should be either physical or video based, not a combination.

Am I doing this right? Structured self-assessment during simulation training of mastoidectomy improves cadaver dissection performance: a prospective educational study.

PURPOSE: Temporal bone surgery requires excellent surgical skills and simulation-based training can aid novices' skills acquisition. However, simulation-based training is challenged by early stagnation of performance after few performances. Structured self-assessment during practice might enhance learning by inducing reflection and engagement in the learning task. In this study, structured self-assessment was introduced during virtual reality (VR) simulation of mastoidectomy to investigate the effects on subsequent performance during cadaveric dissection. METHODS: A prospective educational study with comparison with historical controls (reference cohort). At a temporal bone dissection course, eighteen participants performed structured self-assessment during 3 h of VR simulation mastoidectomy training before proceeding to cadaver dissection (intervention cohort). At a previous course, eighteen participants received identical VR simulation training but without the structured self-assessment (reference cohort). Final products from VR simulation and cadaveric dissection were recorded and assessed by two blinded raters using a 19-point modified Welling Scale. RESULTS: The intervention cohort completed fewer procedures (average 4.2) during VR simulation training than the reference cohort (average 5.7). Nevertheless, the intervention cohort achieved a significantly higher average performance score both in VR simulation (11.1 points, 95% CI [10.6-11.5]) and subsequent cadaveric dissection (11.8 points, 95% CI [10.7-12.8]) compared with the reference cohort, who scored 9.1 points (95% CI [8.7-9.5]) during VR simulation and 5.8 points (95% CI [4.8-6.8]) during cadaveric dissection. CONCLUSIONS: Structured self-assessment is a valuable learning support during self-directed VR simulation training of mastoidectomy and the positive effect on performance transfers to subsequent cadaveric dissection performance.

The Spatial Distribution of Cellular Voids in the Human Otic Capsule: An Unbiased Quantification of Osteocyte-Depleted Areas.

OBJECTIVE: This study aimed to describe the spatial distribution of osteocyte-depleted areas, so-called cellular voids, in the human otic capsule and compare it with that of otosclerosis. BACKGROUND: Systematic histological studies of the bony otic capsule have revealed an osteoprotegerin (OPG)-mediated inhibition of normal bone remodeling around the inner ear. The resulting accumulation of bony degeneration and dead osteocytes has been thoroughly documented, and the spatial distribution of dead osteocytes and matrix microcracks resembles that of the human ear disease otosclerosis. Clusters of dead osteocytes that may interfere with osteocyte connectivity and thereby the OPG signaling pathway have been described in human temporal bones. It is possible that these cellular voids create disruptions in the antiresorptive OPG signal that may give rise to local pathological remodeling. METHODS: Recently, a method of detecting cellular voids was developed. This study uses unbiased stereology to document the spatial distribution of cellular voids in bulk-stained undecalcified human temporal bone. RESULTS: Cellular voids accumulate around the inner ear and increase in number and size with age. Furthermore, cellular voids are more frequently found in the anterior and lateral regions of the otic capsule, which are known predilection sites of otosclerosis. CONCLUSION: This colocalization of cellular voids and otosclerosis suggests a causal relationship between focal degeneration and otosclerotic remodeling.

Mastoidectomy Training: Is Anatomical Variation Needed? A Randomized, Controlled Trial on Performance and Skills Transfer From Virtual Reality to a Three-Dimensional Printed Model.

OBJECTIVE: Virtual reality (VR) simulation-based training effectively improves novices' mastoidectomy skills. Unfortunately, learning plateaus at an insufficient level and knowledge on optimizing mastoidectomy training to overcome this plateau is needed. In this study, we aim to investigate how training on anatomically different temporal bone cases affects learning, including the effect on retention and transfer of skills. STUDY DESIGN: Randomized controlled trial of an educational intervention. SETTING: The Simulation Center at Copenhagen Academy for Medical Education and Simulation. PARTICIPANTS: Twenty-four medical students from the University of Copenhagen. INTERVENTION: Participants were randomized to practice mastoidectomy on either 12 anatomically varying (intervention group) or 12 identical (control group) cases in a VR simulator. At the end of training and again ~ 3 weeks after training (retention), learners were tested on a new VR patient case and a three-dimensional printed model. MAIN OUTCOME MEASURE: Mastoidectomy performance evaluated by blinded expert raters using a 26-item modified Welling Scale. RESULTS: The intervention and control groups' performance results were comparable at the end of training. Likewise, retention and transfer performances were similar between groups. The overall mean score at the end of training corresponded to approximately 70% of the possible maximum score. CONCLUSIONS: Simulation-based training using anatomical variation was equivalent to training on a single case with respect to acquisition, retention, and transfer of mastoidectomy skills. This suggests that efforts to expose novices to variation during initial training are unnecessary as this variation has limited effect, and-conversely-that educators can expose novices to naturally different anatomical variations without worry of hindered learning.

Cochlear Implant Surgery: Virtual Reality Simulation Training and Transfer of Skills to Cadaver Dissection-A Randomized, Controlled Trial.

BACKGROUND: Cochlear implantation requires excellent surgical skills; virtual reality simulation training is an effective method for acquiring basic competency in temporal bone surgery before progression to cadaver dissection. However, cochlear implantation virtual reality simulation training remains largely unexplored and only one simulator currently supports the training of the cochlear implantation electrode insertion. Here, we aim to evaluate the effect of cochlear implantation virtual reality simulation training on subsequent cadaver dissection performance and self-directedness. METHODS: This was a randomized, controlled trial. Eighteen otolaryngology residents were randomized to either mastoidectomy including cochlear implantation virtual reality simulation training (intervention) or mastoidectomy virtual reality simulation training alone (controls) before cadaver cochlear implantation surgery. Surgical performance was evaluated by two blinded expert raters using a validated, structured assess- ment tool. The need for supervision (reflecting self-directedness) was assessed via post-dissection questionnaires. RESULTS: The intervention group achieved a mean score of 22.9 points of a maximum of 44 points, which was 5.4% higher than the control group's 21.8 points (P = .51). On average, the intervention group required assistance 1.3 times during cadaver drilling; this was 41% more frequent in the control group who received assistance 1.9 times (P = .21). CONCLUSION: Cochlear implantation virtual reality simulation training is feasible in the context of a cadaver dissection course. The addition of cochlear implantation virtual reality training to basic mastoidectomy virtual reality simulation training did not lead to a significant improvement of performance or self-directedness in this study. Our findings suggest that learning an advanced temporal bone procedure such as cochlear implantation surgery requires much more training than learning mastoidectomy.

The cutting edge of customized surgery: 3D-printed models for patient-specific interventions in otology and auricular management-a systematic review.

PURPOSE: 3D-printing (three-dimensional printing) is an emerging technology with promising applications for patient-specific interventions. Nonetheless, knowledge on the clinical applicability of 3D-printing in otology and research on its use remains scattered. Understanding these new treatment options is a prerequisite for clinical implementation, which could improve patient outcomes. This review aims to explore current applications of 3D-printed patient-specific otologic interventions, including state of the evidence, strengths, limitations, and future possibilities. METHODS: Following the PRISMA statement, relevant studies were identified through Pubmed, EMBASE, the Cochrane Library, and Web of Science. Data on the manufacturing process and interventions were extracted by two reviewers. Study quality was assessed using Joanna Briggs Institute's critical appraisal tools. RESULTS: Screening yielded 590 studies; 63 were found eligible and included for analysis. 3D-printed models were used as guides, templates, implants, and devices. Outer ear interventions comprised 73% of the studies. Overall, optimistic sentiments on 3D-printed models were reported, including increased surgical precision/confidence, faster manufacturing/operation time, and reduced costs/complications. Nevertheless, study quality was low as most studies failed to use relevant objective outcomes, compare new interventions with conventional treatment, and sufficiently describe manufacturing. CONCLUSION: Several clinical interventions using patient-specific 3D-printing in otology are considered promising. However, it remains unclear whether these interventions actually improve patient outcomes due to lack of comparison with conventional methods and low levels of evidence. Further, the reproducibility of the 3D-printed interventions is compromised by insufficient reporting. Future efforts should focus on objective, comparative outcomes evaluated in large-scale studies.

Assessing competence in cochlear implant surgery using the newly developed Cochlear Implant Surgery Assessment Tool.

PURPOSE: To develop and gather validity evidence for a novel tool for assessment of cochlear implant (CI) surgery, including virtual reality CI surgery training. METHODS: Prospective study gathering validity evidence according to Messick's framework. Four experts developed the CI Surgery Assessment Tool (CISAT). A total of 35 true novices (medical students), trained novices (residents) and CI surgeons performed two CI-procedures each in the Visible Ear Simulator, which were rated by three blinded experts. Classical test theory and generalizability theory were used for reliability analysis. RESULTS: The CISAT significantly discriminated between the three groups (p < 0.001). The generalizability coefficient was 0.76 and most of the score variance (53.3%) was attributable to the participant and only 6.8% to the raters. When exploring a standard setting for CI surgery, the contrasting groups method suggested a pass/fail score of 36.0 points (out of 55), but since the trained novices performed above this, we propose using the mean CI surgeon performance score (45.3 points). CONCLUSION: Validity evidence for simulation-based assessment of CI performance supports the CISAT. Together with the standard setting, the CISAT might be used to monitor progress in competency-based training of CI surgery and to determine when the trainee can advance to further training.

Cochlear implantation: Exploring the effects of 3D stereovision in a digital microscope for virtual reality simulation training - A randomized controlled trial.

In cochlear implantation (CI), excellent surgical technique is critical for hearing outcomes. Recent advances in temporal bone Virtual Reality (VR) training allow for specific training of CI and through introduction of new digital microscopes with ultra-high-fidelity (UHF) graphics. This study aims to investigate whether UHF increases performance in VR simulation training of CI electrode insertion compared with conventional, screen-based VR (cVR). METHODS: Twenty-four medical students completed a randomized, controlled trial of an educational intervention. They performed a total of eight CI electrode insertions each in blocks of four using either UHF-VR or cVR, in randomized order. CI electrode insertion performances were rated by two blinded expert raters using a structured assessment tool supported by validity evidence. RESULTS: Performance scores in cVR were higher than in the UHF-VR simulation although this was not significant (19.8 points, 95% CI [19.3-20.3] vs. 18.8 points, 95% CI [18.2-19.4]; P = 0.09). The decisive factor for performance was participants' ability to achieve stereovision (mean difference = 1.1 points, 95% CI [0.15-2.08], P = 0.02). DISCUSSION: No additional benefit was found from UHF-VR over cVR training of CI electrode insertion for novices. Consequently, standard cVR simulation should be used for novices' basic skills acquisition in CI surgery. Future studies should instead explore the effects of other improvements in CI surgery training and if the lacking benefit of UHF-VR also applies for more experienced learners. CONCLUSION: The increased graphical perception and the superior lifelikeness of UHF-VR does not improve early skills acquisition of CI insertion for novices.

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.

Identification of Cellular Voids in the Human Otic Capsule.

The otic capsule consists of dense highly mineralized compact bone. Inner ear osteoprotegerin (OPG) effectively inhibits perilabyrinthine remodeling and otic capsular bone turnover is very low compared to other bone. Consequently, degenerative changes like dead osteocytes and microcracks accumulate around the inner ear. Osteocytes are connected via canaliculi and need a certain connectivity to sustain life. Consequently, stochastic osteocyte apoptosis may disrupt the osteocytic network in unsustainable patterns leading to widespread cell death. When studying bulk-stained undecalcified human temporal bone, large clusters of dead osteocytes have been observed. Such "cellular voids" may disrupt the perilabyrinthine OPG mediated remodeling inhibition possibly leading to local remodeling. In the common ear disease otosclerosis pathological bone remodeling foci are found exclusively in the otic capsule. We believe the pathogenesis of otosclerosis is linked to the unique bony dynamics of perilabyrinthine bone and cellular voids may represent a starting point for otosclerotic remodeling. This study aims to identify and characterize cellular voids of the human otic capsule. This would allow future cellular void quantification and comparison of void and otosclerotic distribution to further elucidate the yet unknown pathogenesis of otosclerosis.

Cochlear implant surgery: Learning curve in virtual reality simulation training and transfer of skills to a 3D-printed temporal bone - A prospective trial.

OBJECTIVE: Mastering Cochlear Implant (CI) surgery requires repeated practice, preferably initiated in a safe - i.e. simulated - environment. Mastoidectomy Virtual Reality (VR) simulation-based training (SBT) is effective, but SBT of CI surgery largely uninvestigated. The learning curve is imperative for understanding surgical skills acquisition and developing competency-based training. Here, we explore learning curves in VR SBT of CI surgery and transfer of skills to a 3D-printed model. METHODS: Prospective, single-arm trial. Twenty-four novice medical students completed a pre-training CI inserting test on a commercially available pre-drilled 3D-printed temporal bone. A training program of 18 VR simulation CI procedures was completed in the Visual Ear Simulator over four sessions. Finally, a post-training test similar to the pre-training test was completed. Two blinded experts rated performances using the validated Cochlear Implant Surgery Assessment Tool (CISAT). Performance scores were analyzed using linear mixed models. RESULTS: Learning curves were highly individual with primary performance improvement initially, and small but steady improvements throughout the 18 procedures. CI VR simulation performance improved 33% (p < 0.001). Insertion performance on a 3D-printed temporal bone improved 21% (p < 0.001), demonstrating skills transfer. DISCUSSION: VR SBT of CI surgery improves novices' performance. It is useful for introducing the procedure and acquiring basic skills. CI surgery training should pivot on objective performance assessment for reaching pre-defined competency before cadaver - or real-life surgery. Simulation-based training provides a structured and safe learning environment for initial training. CONCLUSION: CI surgery skills improve from VR SBT, which can be used to learn the fundamentals of CI surgery.

OpenEar Image Data Enables Case Variation in High Fidelity Virtual Reality Ear Surgery.

BACKGROUND: Virtual reality (VR) simulation is an established option for temporal bone surgical training. Most VR simulators are based on computed tomography imaging, whereas the Visible Ear Simulator (VES) is based on high-fidelity cryosections of a single temporal bone specimen. Recently published OpenEar datasets combine cone-beam computed tomography (CBCT) and micro-slicing to achieve similar model quality. This study explores integration of OpenEar datasets into VES to enable case variation in simulation with implications for patient-specific modeling based on CBCT. METHODS: The OpenEar dataset consists of segmented, coregistered, multimodal imaging sets of human temporal bones. We derived drillable bone segments from the dataset as well as triangulated surface models of critical structures such as facial nerve or dura. Realistic visualization was achieved using coloring from micro-slicing, custom tinting, and texture maps. Resulting models were validated by clinical experts. RESULTS: Six of the eight OpenEar datasets could be integrated in VES complete with instructional guides for various temporal bone surgical procedures. Resulting models were of high quality because of postprocessing steps taken to increase realism including colorization and imaging artifact removal. Bone artifacts were common in CBCT, resulting in dehiscences that most often could not be found in the ground truth micro-slicing data. CONCLUSION: New anatomy models are included in VES version 3.5 freeware and provide case variation for training which could help trainees to learn more quickly and transferably under variable practice conditions. The use of CBCT for VR simulation models without postprocessing results in bone artifacts, which should be considered when using clinical imaging for patient-specific simulation, surgical rehearsal, and planning.

Distribution of microcrack surface density in the human otic capsule.

BACKGROUND: The bony otic capsule is comprised of highly mineralized and dense compact bone. It is rarely remodelled and degenerative changes, therefore, accumulate around the inner ear. It is also a predilection site for the pathological remodelling seen in otosclerosis. Morphometric studies have documented increased numbers of dead osteocytes and microcracks in the human otic capsule. Microcracks may disrupt the lacuno-canalicular network and cause osteocyte apoptosis ultimately breaking up the perilabyrinthine bone signalling pathways and dynamics. This may be important to understand the pathogenesis of remodelling diseases like otosclerosis. AIMS/OBJECTIVES: This study describes the spatial and regional distribution of microcrack surface density in relation to the inner ear and compares it to that previously recorded for otosclerosis. MATERIAL AND METHODS: Forty-two temporal bones and five ribs were used. All samples were undecalcified, bulk stained in basic fuchsin and plastic embedded. Unbiased stereology was used to estimate the true surface density of microcracks (mm2/mm3) in perilabyrinthine bone. RESULTS: The surface density of microcracks accumulates around the inner ear spaces, particularly in the lateral window regions, and increases with age. CONCLUSIONS AND SIGNIFICANCE: This study documents the spatial and temporal association between microfractures and otosclerosis in the otic capsule.

3D-Printed Models for Temporal Bone Surgical Training: A Systematic Review.

OBJECTIVE: 3D-printed models hold great potential for temporal bone surgical training as a supplement to cadaveric dissection. Nevertheless, critical knowledge on manufacturing remains scattered, and little is known about whether use of these models improves surgical performance. This systematic review aims to explore (1) methods used for manufacturing and (2) how educational evidence supports using 3D-printed temporal bone models. DATA SOURCES: PubMed, Embase, the Cochrane Library, and Web of Science. REVIEW METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, relevant studies were identified and data on manufacturing and validation and/or training extracted by 2 reviewers. Quality assessment was performed using the Medical Education Research Study Quality Instrument tool; educational outcomes were determined according to Kirkpatrick's model. RESULTS: The search yielded 595 studies; 36 studies were found eligible and included for analysis. The described 3D-printed models were based on computed tomography scans from patients or cadavers. Processing included manual segmentation of key structures such as the facial nerve; postprocessing, for example, consisted of removal of print material inside the model. Overall, educational quality was low, and most studies evaluated their models using only expert and/or trainee opinion (ie, Kirkpatrick level 1). Most studies reported positive attitudes toward the models and their potential for training. CONCLUSION: Manufacturing and use of 3D-printed temporal bones for surgical training are widely reported in the literature. However, evidence to support their use and knowledge about both manufacturing and the effects on subsequent surgical performance are currently lacking. Therefore, stronger educational evidence and manufacturing knowhow are needed for widespread implementation of 3D-printed temporal bones in surgical curricula.

Microcrack surface density in the human otic capsule: An unbiased stereological quantification.

Bone is continuously remodeled to repair and strengthen degenerative bone with accumulating dead osteocytes and microfractures. Inner ear osteoprotegerin (OPG)-mediated inhibition of otic capsular bone remodeling causes excessive perilabyrinthine bone degeneration. Consequently, microcracks accumulate around the inner ear. Microcracks cause osteocyte apoptosis and may disrupt the canalicular network connecting osteocytes. Despite their linear microscopic appearance, microcracks are three-dimensional disruption planes and represent surface areas inside a tissue space. With an elevated microcrack burden the number of disconnected osteocytes is expected to increase. This may prove relevant to ongoing research in otic focal pathologies like otosclerosis. Therefore, an unbiased quantification of the microcrack surface density (mm2 /mm3 ) in the human otic capsule is essential. In this study unbiased stereology was applied to undecalcified bulk stained human temporal bones to demonstrate its feasibility in describing the three-dimensional reality behind two dimensional observations of microcracks. A total of 28 human temporal bones and five ribs were bulk stained in basic fuchsin, serially sectioned and hand-ground to a thickness of 80-120 µm. Both horizontal and vertical sections were produced and compared. This study showed that surface density of microcracks was significantly higher around the inner ear compared to ribs. Furthermore, no significant difference in microcrack surface density between horizontal and vertical sections in the temporal bone was demonstrated.

Understanding the effects of structured self-assessment in directed, self-regulated simulation-based training of mastoidectomy: A mixed methods study.

OBJECTIVE: Self-directed training represents a challenge in simulation-based training as low cognitive effort can occur when learners overrate their own level of performance. This study aims to explore the mechanisms underlying the positive effects of a structured self-assessment intervention during simulation-based training of mastoidectomy. METHODS: A prospective, educational cohort study of a novice training program consisting of directed, self-regulated learning with distributed practice (5x3 procedures) in a virtual reality temporal bone simulator. The intervention consisted of structured self-assessment after each procedure using a rating form supported by small videos. Semi-structured telephone interviews upon completion of training were conducted with 13 out of 15 participants. Interviews were analysed using directed content analysis and triangulated with quantitative data on secondary task reaction time for cognitive load estimation and participants' self-assessment scores. RESULTS: Six major themes were identified in the interviews: goal-directed behaviour, use of learning supports for scaffolding of the training, cognitive engagement, motivation from self-assessment, self-assessment bias, and feedback on self-assessment (validation). Participants seemed to self-regulate their learning by forming individual sub-goals and strategies within the overall goal of the procedure. They scaffolded their learning through the available learning supports. Finally, structured self-assessment was reported to increase the participants' cognitive engagement, which was further supported by a quantitative increase in cognitive load. CONCLUSIONS: Structured self-assessment in simulation-based surgical training of mastoidectomy seems to promote cognitive engagement and motivation in the learning task and to facilitate self-regulated learning.