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.

An endoscopic Ear Trainer for the low-resource setting.

BACKGROUND: Endoscopic ear surgery is a technique that is growing in popularity. It has potential advantages in the low-resource setting for teaching and training, for the relative ease of transporting and storing the surgical equipment and for telemedicine roles. There may also be advantages to the patient, with reduced post-operative pain, facilitating the ability to complete procedures as out-patients. METHODS: Our Ear Trainer has previously been validated for headlight and microscope otology skills, including foreign body removal and ventilation tube insertion, in both the high- and low-resource setting. This study aimed to assess the Ear Trainer for similar training and assessment of endoscopic ear surgery skills in the low-resource setting. The study was conducted in Uganda on ENT trainees. RESULTS: Despite a lack of prior experience with endoscopes, with limited practice time most participants showed improvements in: efficiency of instrument movement, steadiness of the camera view obtained, overall global rating of the task and performance time (faster task performance). CONCLUSION: These results indicate that the Ear Trainer is a useful tool in the training and assessment of endoscopic ear surgery skills.

The Economics of Surgical Simulation.

There are massive hidden costs in the current paradigm of surgical training related to increased operative times for procedures with resident involvement and costs of medical errors. Shifting procedural training outside of the operating room through use of simulation has the potential to improve patient safety, minimize learning time to achieve competency, and increase operative efficiency. Investment in surgical simulation has the potential to reduce costs to health care systems through improved operating room efficiency and reduction of medical errors. This article explores the economic costs related to surgical training in otolaryngology and the value of investment in surgical simulation.

Development and validation of a low-cost microsurgery Ear Trainer for low-resource settings.

OBJECTIVE: Chronic suppurative otitis media is a neglected condition affecting up to 330 million people worldwide, with the burden of the disease in impoverished countries. The need for non-governmental organisations to hardwire training into their programmes has been highlighted. An ear surgery simulator appropriate for training in resource-poor settings was developed, and its effectiveness in facilitating the acquisition of headlight and microsurgical skills necessary to safely perform procedures via the ear canal was investigated. METHODS: Face validity was assessed via questionnaires. Six tasks were developed: a headlight foreign body removal task, and microscope tasks of foreign body removal, ventilation tube insertion, tympanomeatal flap raising, myringoplasty and middle-ear manipulation. Participants with varying ENT experience were video-recorded performing each task and scored by a blinded expert observer to assess construct validity. RESULTS: Face validity results confirmed that our Ear Trainer was a realistic representation of the ear. Construct validity results showed a statistically significant trend, with experts performing the best and those with limited experience performing better than novices. CONCLUSION: This study validates our Ear Trainer as a useful training tool for assessing headlight and microsurgical skills required to perform otological procedures.

Assessment of skills using a virtual reality temporal bone surgery simulator.

Surgery on the temporal bone is technically challenging due to its complex anatomy. Precise anatomical dissection of the human temporal bone is essential and is fundamental for middle ear surgery. We assessed the possible application of a virtual reality temporal bone surgery simulator to the education of ear surgeons. Seventeen ENT physicians with different levels of surgical training and 20 medical students performed an antrotomy with a computer-based virtual temporal bone surgery simulator. The ease, accuracy and timing of the simulated temporal bone surgery were assessed using the automatic assessment software provided by the simulator device and additionally with a modified Final Product Analysis Scale. Trained ENT surgeons, physicians without temporal bone surgical training and medical students were all able to perform the antrotomy. However, the highly trained ENT surgeons were able to complete the surgery in approximately half the time, with better handling and accuracy as assessed by the significant reduction in injury to important middle ear structures. Trained ENT surgeons achieved significantly higher scores using both dissection analysis methods. Surprisingly, there were no significant differences in the results between medical students and physicians without experience in ear surgery. The virtual temporal bone training system can stratify users of known levels of experience. This system can be used not only to improve the surgical skills of trained ENT surgeons for more successful and injury-free surgeries, but also to train inexperienced physicians/medical students in developing their surgical skills for the ear.

Face validity study of an artificial temporal bone for simulation surgery.

HYPOTHESIS: Using the rapid prototype (RP) technology, a physical construct of a human temporal bone was developed based on cadaveric tissue to permit simulated surgical training. The objective of the study was to test the face validity of the model. BACKGROUND: The cost and access to human cadaveric temporal bones is becoming increasingly challenging, particularly if there are religious and regulatory restrictions. There is a need to develop alternative strategies to improve accessibility. METHODS: Ultra high-resolution computed tomography (CT) images (0.15-mm resolution) were obtained from a cadaver temporal bone. Manual segmentation and conversion into a stereolithography file format permitted printing on a RP stereolithography printer. A 3-dimensional physical model was hardened to achieve the desired consistency. Eight practicing otologists were recruited to evaluate this model. Respondents were asked to drill the artificial bone and complete a rating survey upon completion. RESULTS: In using a Likert scale between 1 and 5, results for anatomic accuracy were favorable, with the best scores for overall morphology (4.63) and for lateral structures within the bone (4.5). The poorest scores were for the semicircular canals (3.75) and chorda tympani (3.25). Scores for haptic realism were good as well. The average score for the question "overall, how valuable is the model as a surgical simulator" was 4.1. The experts felt that junior residents (PGY 1-3) would benefit most from this surgical education model. CONCLUSION: The outer structures of the RP artificial temporal bone can be considered to have face validity. Improvements will continue to be made to address some of the deficiencies in the anatomic and haptic realism of this model.

High-fidelity, inexpensive surgical middle ear simulator.

HYPOTHESIS: A high-fidelity, inexpensive middle ear simulator could be created to enhance surgical training that would be rated as having high face validity by experts. BACKGROUND: With rapid prototyping using additive manufacturing technology (AMT), one can create high-resolution 3-dimensional replicas of the middle ear at low cost and high fidelity. Such a simulator could be of great benefit for surgical training, particularly in light of new resident training guidelines. METHODS: AMT was used to create surgical middle ear simulator (SMS) with 2 different materials simulating bone and soft tissue. The simulator is composed of an outer box with dimensions of an average adult external auditory canal without scutum and an inner cartridge based on an otosclerosis model. The simulator was then rated by otology experts in terms of face validity and fidelity as well as their opinion on the usefulness of such a device. RESULTS: Eighteen otologists from 6 tertiary academic centers rated the simulator; 83.3% agreed or highly agreed that SMS has accurate dimensions and 66.6% that it has accurate tactile feedback. When asked if performance of stapedotomy with the SMS improves with practice, 46% agreed. As to whether practicing stapedotomy with the SMS translates to improvement with live surgery, 78% agreed with this statement. Experts' average rating of the components of SMS (of possible 5) was as follows: middle ear dimensions, 3.9; malleus, 3.7; incus, 3.6; stapes, 3.6; chorda tympani, 3.7; tensor tympani, 4.1; stapedius, 3.8; facial nerve, 3.7; and promontory, 3.5. Overall, 83% found SMS to be at least "very useful" in training of novices, particularly for junior and senior residents. CONCLUSION: Most experts found the SMS to be accurate, but there was a large discrepancy in rating of individual components. Most found it to be very useful for training of novice surgeons. With these results, we are encouraged to proceed with further refinements that will strengthen the SMS as a training tool for otologic surgery.

Objective skills assessment and construct validation of a virtual reality temporal bone simulator.

OBJECTIVES: To evaluate construct validity of the Voxelman TempoSurg Virtual Reality (VR) temporal bone simulator by determining whether generated objective metrics can distinguish experienced otologic surgeons from intermediate and novice surgeons. DESIGN: Prospective assessment study. SETTING: Two university-affiliated teaching hospitals. PARTICIPANTS: Sixty-five participants were recruited; 40 novice surgeons, 15 trainees in otolaryngology, and 10 experienced otolaryngology consultants with a specialist interest in otology were individually assessed on a standardized simulated temporal bone task. The task involved identification and delineation of the sigmoid sinus in a virtual left-sided temporal bone. MAIN OUTCOME MEASURES: Objective data were produced using a scoring matrix incorporated into the VOXEL MAN TempoSurg software. The simulator measured the total time taken to complete the task, the volume and efficiency of bone removal and error data for excessive force or injury to the facial nerve, dura, and sigmoid sinus. RESULTS: Experts and intermediates outperformed novices with respect to the total time taken to complete the task (expert versus novice: p < 0.001; intermediate versus novice: p < 0.001), total volume of bone removed (p < 0.001 and p = 0.03), efficiency of bone removal (p < 0.001 and p < 0.001), time spent with the drill tip obscured (p = 0.002 and p < 0.001), and number of injuries to the sigmoid sinus (p < 0.001 and p < 0.001). The intermediate group injured the sigmoid sinus on more occasions than the experts (p = 0.008) and were less efficient than experienced surgeons (p = 0.005). CONCLUSION: Simulator-generated objective metrics can be used to differentiate individuals of differing levels of experience using a standardized temporal bone task. VR simulation has potential as a training tool and may have a role in both formative and summative assessment.

Objective assessment of learning curves for the Voxel-Man TempoSurg temporal bone surgery computer simulator.

INTRODUCTION: Simulators are becoming an increasingly important part of surgical training. Temporal bone surgery is one area in which simulators, such as the Voxel-Man TempoSurg simulator, are likely to play a significant role in training. We present learning curve data from novice trainees using this simulator to learn cortical mastoidectomy, exposure of the sigmoid sinus, and exposure of the short process of the incus. METHODS: We measured the time taken to perform the procedures, the volume of reference bone removed, and the structures damaged during dissection. RESULTS: We found improvement in a number of parameters over the course of the study. The overall scores, structural damage scores and time taken improved, to differing degrees, for each task. The volume of reference bone removed remained constant. CONCLUSION: These results indicate that the trainees' efficiency improved as they became more proficient at removing a given volume of reference bone.

Pilot testing of an assessment tool for competency in mastoidectomy.

OBJECTIVES/HYPOTHESIS: To determine the feasibility, validity, and reliability of an evaluation tool for the assessment of competency in mastoid surgery. This study tests the hypothesis that residents of dissimilar training levels differ in their technical performance as measured by this tool. STUDY DESIGN: Cross-sectional validation study. METHODS: Two or more faculty otolaryngologists evaluated each resident performing a cortical mastoidectomy on a cadaveric temporal bone. Performance was rated using global and checklist components of a mastoidectomy assessment tool. RESULTS: Fifteen internal and external faculty members evaluated 23 residents over 3 years resulting in 118 evaluations. Construct validity was observed as scores increased with clinical training year. These differences were greater for more complex tasks. There was a percentage agreement of 78.5% between evaluator pairs in the determination of pass (score 3-5) versus fail (score 1-2) for the checklist instrument, and an agreement of 74.4% for the global instrument. Although agreement was lower for the exact score on a scale of 1 to 5, differences of 1 or less occurred in over 80% of evaluator pairs. Regression analysis confirmed faculty perception that sharpening of the posterior external auditory canal cortex and opening of the antrum from posterior to anterior are strong predictors of overall surgical performance. CONCLUSIONS: Our results indicate that the tool we have developed is a feasible, valid, and reliable instrument for the assessment of competency in mastoidectomy. The instrument can be used to provide formative feedback and to identify procedural tasks for which additional training may be necessary.

[Multi-center study of the Jenaer model of the temporal bone]. / Multicenterstudie zum Jenaer Felsenbeinmodell.

BACKGROUND: Preparing exercises at the temporal bone are a prerequisite for the knowledge of the anatomical special features of this region and for learning the fundamentals of the tympanic cavity surgery. Since however fewer human temporal bones are available, the search for back-up models already took place in the last years. METHODS: Based on the experiences of the handling and visualization of CT data for the 3D-implant construction in the ent department Jena a temporal bone model was developed. The model was sent away to surgeons of different training. On the basis of identification of anatomical structures and evaluation of general parameters by means of a point system the model was evaluated. RESULTS AND CONCLUSIONS: The Jenaer temporal bone model is suitable as entrance into the preparing exercises. The anatomical structures are good to identify for the beginner. The handling with drill and chisel can be learned.