Validation of a simulator for temporomandibular joint arthroscopy


The traditional method of surgical training has followed the ‘observe, practice, and teach’ model, which is useful for open surgery, but is insufficient for minimally invasive surgery. This study presents the validation of a new simulator designed for TMJ arthroscopy training. A group of 10 senior maxillofacial surgeons performed an arthroscopy procedure using the simulator. They then completed a questionnaire analyzing the realism of the simulator, its utility, and the educational quality of the audiovisual software. The mean age of the 10 surgeons was 42.6 years, and they had performed a mean 151 arthroscopies. With regard to the realism of the simulator, 80% reported that it was of an appropriate size and design and 70% referred to the very realistic positions and relationships between the internal structures. Regarding its educational potential, 80% reported the simulator to be very useful for acquiring the basic skills and to acquire the sensation of depth during access to the TMJ. Finally, 90% reported the prototype to be very useful for TMJ arthroscopy training. These preliminary results showed a high degree of approval. The general opinion of the group of experts was that the experience was rewarding and inspiring, and that the prototype has the educational potential for the achievement of basic TMJ arthroscopy skills.

The use of simulators for skills training is a common practice in our daily life, although we are probably unaware of this. Video games, virtual simulators in aeronautical engineering, and fire drills to evacuate a building are examples of simulations used in our daily routine. A training simulator can be defined as any system that provides the most realistic possible imitation of the steps necessary to follow in a specific procedure. Simulators are usually intended to recreate a real scenario in which events do not occur in an arbitrary way, but rather are previously planned. In this way, training with simulation allows the same procedure to be repeated as many times as needed until the basic skills are acquired, which will later be used in real life.

Generally, simulators are categorized into two types, realistic and virtual. However, it is becoming increasingly more common to find hybrid simulators that combine a device or real scenario with virtual reality software. The use of such simulators in the various fields of Medicine is widespread, such as the use of mannequins to learn to find a blood vessel and to perform the manoeuvres for cardiopulmonary resuscitation or orotracheal intubation.

In surgery, the use of simulators has been common practice for years. There is a multitude of designs – physical, virtual, and hybrid – with hybrid designs being the most recent and undergoing constant development. Another model is the use of animals in experiments, for which anatomical dissimilarities need to be taken into account. Despite the efforts made to find the perfect simulator, the cadaver continues to be the gold standard due to its close resemblance to the real patient. However, the cadaver has certain drawbacks, such as the high cost, the legal requirements, lack of availability in all hospitals, lack of reusability, failure to reproduce different pathologies, and numerous political, cultural, and religious considerations.

For surgical training, most learning programmes in recent decades have followed the Halstedian model, which consists of ‘observing, practicing, and teaching’. Surgeons without experience acquire autonomy in a progressive way as they follow surgical procedures under the supervision of an expert surgeon. Nevertheless, there are many limitations to the traditional training method including high costs, the pressure to be present, limited training time, difficulties in monitoring, ethical and legal restrictions, and the lack of standardization; furthermore, it depends on the number of patients, the opportunities for learning, and the advent of new minimally invasive techniques. As a consequence of all these drawbacks, numerous training modalities for surgical techniques have been developed outside the operating room so that the surgeon can negotiate the learning curve before moving on to real patients.

Within the field of maxillofacial surgery, arthroscopy of the temporomandibular joint (TMJ) is a common technique that has proven effective in the diagnosis and treatment of TMJ disorders. However, the difficulties of the technique make learning complex and sometimes frustrating. Given the extensive experience of the present study team in performing TMJ arthroscopy procedures, there is an apparent obligation for us to offer our surgeons, visitors, and residents a method that will enable them to learn the technique. This method should be reproducible, accessible to any specialist, and allow them to keep updated.

A realistic physical simulator that has been developed for training in arthroscopy of the TMJ is presented herein. The prototype has been constructed according to anthropometric standards using a material that reproduces the different textures and colours of all anatomical parts in the design (Neoderma, Brasil) ( Fig. 1 ). Thus, the skin, subcutaneous tissue, parotid gland, facial nerve, temporal vessels, ligaments, and articular capsule can be distinguished ( Fig. 2 ). In addition, a virtual teaching unit has been designed that consists of an electronic device connected to the simulator, which contains a library of contents grouped into different categories, including theoretical information such as explanatory videos.

Fig. 1
Design of the prototype.

Fig. 2
(A) The anatomical components of the prototype, including vessels, nerves, and parotid gland. (B) The masseter muscle is found in a deeper layer. (C) The joint capsule and ligaments involving the TMJ are designed using the same material.

The aim of this study was to obtain and report preliminary results for the validation of the simulator. This validation study involved a group of recognized maxillofacial surgeons from Spain with experience in the area of endoscopic surgery of the TMJ, who analyzed both the realism and the teaching potential of the simulator.

Materials and methods

A group of 10 expert surgeons was formed to execute a sequential practice exercise in which they performed an arthroscopy in the simulator and afterwards analyzed the audiovisual contents of the teaching unit. After the completion of both exercises, all of the participants completed a questionnaire to evaluate the realism of the model and its usefulness in surgical training. In addition, the surgeons were given the opportunity to express their personal opinions of the experience.

The first practice exercise consisted of performing an arthroscopy of the right side under the supervision of an expert surgeon and the engineer collaborating on the project ( Fig. 3 ). The exercise was carried out with a Storz arthroscope (Karl Storz-Endoskope, Tuttlingen, Germany) using an eyepiece angled at 30° with a diameter of 2.3 mm (identical to the one used in the clinic); a tracker was added to monitor the speed, time, and precision of each movement, for data analysis in subsequent studies.

Fig. 3
(A) Arthroscopic procedure performed during the study: introducing the second cannula. (B) The final positions of the devices.

All of the participants had to complete the following steps of the practice exercise ( Fig. 4 ): (1) Access the superior joint space of the TMJ. (2) Complete the examination from the posterior to the anterior recess, identifying all the joint structures during this movement (retrodiscal tissues, posterior ligament, articular disc, glenoid fossa, anterior recess, and pterygoid window). (3) Repeat the movement towards the back. (4) Insert the drainage cannula and triangulate. (5) Use a cutting instrument, via a second cannula, and eliminate an adhesion.

Fig. 4
(A) First, the glenoid cavity, the retrodiscal tissues, and the ligament are found. (B) Along the joint cavity, the surface of the disc shows signs of synovitis. (C) With the second cannula, the texture of the disc can be perceived. (D) In a forward position, the pterygoid window is found. (E) The second cannula can be used to perform the myotomy of the pterygoid muscle. (F) The presence of adhesions can be detected and these can be dissected.

As the surgeons completed the practice exercise, they started to examine the teaching unit that contained different explanatory videos classified by theoretical content. The participants then completed the parts of the questionnaire referring to the teaching unit, and in this case, as in the practice exercise, most of the surgeons expressed their personal opinion of the unit.


Ten surgeons participated, of whom nine were male and one was female; their average age was 42.6 years. All of the participants had prior experience in TMJ arthroscopy, averaging 11.5 years (range 1–26 years). The average number of arthroscopies undertaken by each of the participants was 151; the average number of arthroscopies at which the participant was an assistant was 147. Regarding prior experience using other types of simulator, only one surgeon had previously used a simulator.

In terms of formative experience in maxillofacial surgery, eight of the participants had been trained surgically as residents in different hospitals in Spain, a task that they had been involved in for years. Of these surgeons, seven did so specifically using the endoscopic technique for the TMJ.

In relation to the frequency with which they played video games, 40% claimed never to have played them, while 40% played occasionally and 20% did so once a month.

After the practice exercise had been completed, all of the participants completed a questionnaire that was divided into blocks: evaluation of the realism of the simulator, evaluation of its potential as an educational tool, and personal opinion. The items analyzed in the block referring to the realism of the simulator are listed in Table 1 . These were scored from 1 to 5, with a score of 1 representing ‘not very realistic’ and a score of 5 representing ‘perfectly realistic’. The items with the highest scores were the general external appearance of the simulator in terms of proportions and the locations of the anatomical structures, the sizes of the internal structures, and the locations of the internal structures and the relationships between them. The item with the lowest score related to the capacity of the simulator to maintain the saline solution within the joint cavity during irrigation, since the device was not completely watertight.

Table 1
Evaluation of the realism of the simulator.
Not realistic
Not very realistic
Quite realistic
Very realistic
Perfectly realistic
The general external appearance of the simulator (proportions and locations of the anatomical structures) 10% 40% 50%
Tactile sensation experienced with the instruments during the procedure 10% 50% 40%
Sizes of the internal structures of the joint cavity 10% 10% 80%
The appearance of the internal tissues of the cavity 10% 50% 40%
Water tightness of the joint during the irrigation manoeuvres 20% 20% 40% 20%
Locations of the internal structures of the cavity and the relationships between these (temporal fossa, joint disc, retrodiscal tissue) 30% 70%
The realism of the pathologies incorporated into the simulator 20% 60% 20%
The relationship between the external anatomical structures used as a reference for access to the cavity and the joint cavity itself 70% 30%

On analyzing the overall data, it was found that most of the scores corresponded to the highest evaluation level, thus in general all of the participants characterized the prototype as at least ‘very realistic’.

When asked about the skin, muscle, and joint capsule resistance in the simulator, 70% considered it less than in a real patient, and this quality was felt to lower the training value of the simulator for almost 50% of the subjects.

The second block of questions was designed to analyze the teaching potential of the prototype (data in Table 2 ). The results proved similar, given that the participants regarded the simulator as a good tool with which to learn basic skills, to perceive the depth of field, and to practice the movement of the instruments within the joint cavity and gain access to the joint.

Table 2
Evaluation of the educational potential of the simulator.
Not useful
Not very useful
Quite useful
Very useful
To acquire the basic skills needed during arthroscopic TMJ surgery 20% 80%
To acquire the sensation of depth (insertion/extraction) through the monitor used during the TMJ arthroscopic surgery 10% 10% 80%
To learn to orientate the arthroscopic optics (rotation) within the joint cavity 10% 90%
To learn the access manoeuvre into the joint with the laparoscope approach 20% 80%
To learn to place the drainage cannula necessary to irrigate the TMJ 10% 10% 10% 70%
To learn the manoeuvre of inserting the second cannula 30% 70%
To acquire the skills for triangulating during TMJ arthroscopy 30% 70%
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Jan 16, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Validation of a simulator for temporomandibular joint arthroscopy
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