Acquiring anatomical and surgical skills in otology is a rigorous task. Of utmost importance is continuous hands-on experience: this allows for hand-eye coordination improvement, acquiring knowledge of surgical maneuverability in a confined area, learning the handling of both tissue and instruments, as well as gaining knowledge of the complex relationships of different anatomical structures in a confined space.
One of the consequences of the COVID 19 pandemic is the limitation of personal and academic funding, which has led to an even greater imbalance between LMICs and HICs in the possibility of training in specialized surgical procedures. Different training models have been proposed including cadaveric dissections, various animal models, 3D printed models and virtual or augmented reality. A comprehensive comparison of available models concluded that cadaveric models remain the best platform for temporal bone training[12]. The major drawback of any animal model is the lack of anatomical validity, but when we compare both availability and cost, the animal model superseded the cadaveric one.
Although 3-dimensional surgical models of the temporal bone—specifically virtual reality (VR) and 3-D printing - have been shown to be applicable and shorten the learning curve in training the otological surgeon[12], [13], these methods are still in their infancy. Printable models may highly resemble bony structures, but the addition of soft tissue (nerves, blood vessels, connective tissue) in these structures complicates the production process and makes these models both expensive and inaccessible[14]. Furthermore, tactile sensation in a 3-D model does not resemble ovine cadaveric dissection, which is adequately similar to human cadaveric dissection. In comparison to the model we present, any given 3-D printed model would be more expensive and require both software/hardware that may be unobtainable in some low-resource settings.
Ovine heads are abundant almost anywhere in the world and can be acquired with minimal or no cost in most countries. Specimen preparation and manipulation are easily learned as we have shown in a stepwise fashion. No specialized materials are necessary, and even house-hold drills can be used for bony work.
Another advantage of the ovine model is the resemblance of both outer and middle ear anatomy to that of humans. While acquiring both surgical/manual expertise, one acquires anatomical understanding of the tympanic membrane, its placement and relationship to the malleus, the understanding of the ossicular chain as well as the placement of the facial nerve and its various relationships.
In 2 studies published by Clark et al.[15], [16] the authors state several benefits that may be attained from the implementation of endoscopic ear surgery in LMIC. The first, both pathology and operative technique can be equally observed by the surgeon and the staff, which is an essential step for education. Secondly, the ease of transportation and storage of equipment, as well as the ease with which the technique would lend itself towards telemedicine roles may be noted. Reduced post-operative pain and an increase in same day surgery rates are also an advantage in LMICs. The one challenge, stated by the authors, is the obstacle of providing effective medical education in ear endoscopy in LMIC, taking into account both the greater time and resource constraints in these countries[17]. The authors further state, that a virtual, high-technology simulator would be unrealistic in LMICs, and a simulator should be cost effective, avoid the need for maintenance and disposable components, having realistic dimensions and layout, providing a range of tasks to perform, and be easily transportable. The endoscopic ear training model, presented in our paper, fulfils all these roles. It takes all the benefits and succeeds in succumbing the aforementioned constraints by reducing the need for expensive surgical equipment and enabling a realistic "feel" of both tissue and surgical procedure. Our model enables error-based learning, standardization of learning processes and personal skill acquisition[18]. which is the basis for developing a capable surgeon anywhere in the world.
In another study published by Luu et al.[19] which had an aim of assessing the face and constructing the validity of a specific ear simulator constructed by the authors, the authors have shown that simulation training can allow individuals to gain otological skills in a low-resource settings, they even state that low-fidelity physical models have been shown to achieve similar levels of learning as virtual reality simulators[20], making our model even more appealing since it is both high-fidelity and low-cost.
In this paper we propose, a stepwise training guide depicting photographed anatomy, seen in the figures attached (Fig. 1-6), as well as a written and video-assisted guide for surgical procedures including: TT placement, ossicular removal, stapedotomy, and middle ear debris removal without harming important neighboring structures (e.g., facial nerve, chorda tympani).
The limitations of the ovine model are as follows: the accentuated bullous hypotympanum as well as lack of the annular ligaments, make performing a tympanoplasty almost impossible, the hardened mastoid bone with lack of pneumatization prevents mastoidectomy training and necessitates a Dremel drill in order to perform a meatoplasty. We should add to this the fact that a validation process of the ovine model has not been extensively performed, so some of our presumptions may be unbased.
Due to these limitations, we are now conducting a rigorous validation study of the ovine training model towards human endoscopic surgery.
In our opinion, our smartphone based endoscopic ear training model is ideal for training both students and residents in otolaryngology everywhere and in particular in LMIC where other endoscopic training opportunities may be limited.