Evaluation of a 3D-printed hands-on radius fracture model during teaching courses

For decades, students were learning anatomy from books and drawings. While there exists visualization of basic and correct anatomy with the use of 3-dimensional (3D) models or teaching courses on human corpses, these techniques get rare in case of fracture models. But not only correct anatomy but also pathologies, fracture mechanisms, and basic understanding of surgical therapy are essential for the later clinical career of students. If commercial models are available, buying all of these is an expensive task. 3D-printing technologies like Fused-Filament-Fabrication (FFF) not only offer cost efficient, but innumerable replicability in production [1] of different fracture models which can be used for teaching purposes during courses for students [2].

In this study, a very common fracture should be addressed and aim to increase the understanding by demonstration and evaluation of 3D-printed models: Depending on country and population, fractures of the distal radius are the most common type with 10–25% of all fractures [3‐5]. For that reason, the fracture of the distal radius is integrated with high skill levels within the German National Catalogue of Learning Objectives in Surgery (NKLC) for undergraduate medical students [6]. The fracture lines and mechanisms occur very homogeneous [7] and thus can be classified by the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification [8]. Primarily, they are grouped into A-, B- and C-fractures depending on their severity especially in terms of extra, partial, or complete intra-articular fracture lines.

Division in those classification groups is essential for choice of one of the different therapy options and has high impact on the outcome for the patients [9‐11]. However, even consultants of trauma or orthopaedic surgery rarely seem to classify fractures the same, as multiple results of intra- and interobserver reliability studies show [12, 13]. Therefore, it is even more difficult for students and young residents to correctly assign fractures to the different classification systems. And since these fractures are so common, correct assignment followed by selection of the correct treatment options is even more important. 3D-printing concerns rather technical courses, but becomes more present in medical education, too. For education purposes themselves, it offers various advantages:

Studies by AlAli et al. (2018) have shown that the visualization of learning content in the form of 3D-printed illustrative models significantly increases the learning effect, for example with use in oral and cleft palate models in oral and maxillofacial surgery [14].

There are already commercially available models of many anatomy contents, but using 3D-printed models offers advantages in terms of cheap production and ad hoc availability of different norm variants or special fractures. Wang et al. (2017), for example, were able to show that no advantage could be achieved over a traditional model in comparison to the printed (single-colour) model of a heart [15]. Nevertheless, it would be advantageous to immediately show the learner the link between the diagnostic tools available in the clinical situation, such as X-rays and CT scans, and the anatomical relationship (of the fracture) on site, to possibly create a spatial understanding of the two-dimensional image data sets. Therefore, this study addresses the question of whether 3D-printed models can improve the teaching effectiveness and understanding of anatomy and fracture theory in medical students during their clinical training. In addition, the study will ask how students perceive this new teaching method and whether they think it is helpful.

As previously described models were created and then printed. Each fracture model is shown in Fig. 1. Examples of each fracture are exemplary demonstrated as CT dataset in Fig. 3 and postoperative X-ray in Fig. 4.

Using FFF 3D printing for generating models for medical education is a promising teaching method with multiple advantages. However, 3D-printed models for teaching purposes do not only exist in trauma surgery, such as pelvic [17] or tibial fractures [18], but also in other specialties, e.g., oral and maxillofacial surgery [19, 20]. In this study, the outcome of teaching with different learning methods regarding distal radius fractures was investigated. The results show that the teaching method in fracture anatomy generally is rated with good marks and most of the students liked the course and saw advantages in it. The differences between each method (model, CT data, and X-ray) were small, but the reviews and responses regarding the model were even or better than the other methods. Interestingly, in the AO classification assignment test, the combinations showed the best test results, especially the combination of model/X-ray and CT/model. This might be based on different brain areas used for learning from plane 2D pictures or from holding a model in one´s own hand.

By addressing different brain areas, visual object recognition generates a plastic learning success. DiCarlo et al. (2012) are calling it “core object recognition”, which despite minor differences in the pattern (e.g., small variations of fracture lines in our cases), it allows the fracture to be recognized [21]. The problem of mentally transferring two- to three-dimensional images is also known in other disciplines, e.g., obstetrics with 2D ultrasound being changed to a 3D image, so that such tasks are increasingly being handed over to computer programs through deep learning. This is only possible to a limited extent in trauma surgery [22]. It is precisely this link between two-dimensional X-ray images or 3D-generated (but mostly 2D-displayed) CT data and the real examination findings as well as intraoperative situs that seems essential. Since the traditional teaching methods in the form of books and illustrations convey information primarily in two-dimensional form, the learner can only establish this link at an advanced stage in everyday clinical practice as soon as there are real points of contact, e.g., in the operating theatre. A large proportion of students do not experience parts of this experience during their education, although the surgical specialties in particular, which are finding it increasingly difficult to find young residents not only in Germany but also the rest of the world [23‐25], could and thus should offer a great deal of plasticity. Taking this into consideration students mainly learn from books and digital media during their education, the good results in these groups in the tests could be explained by the experience in such learning media; nevertheless, it also shows that 3D models also generally perform well in the examination situation. Standard fractures are thus easily recognized via pattern recognition in X-rays or CT scans. As radiological images are the main diagnostic tools for fracture teaching in everyday trauma surgery, this is to be supported. However, it is not only the pure recognition of patterns that counts, but also—especially for medical explanation or surgical techniques—the understanding of the fracture mechanism and the proper therapy.

However, everyone learns differently. Such different learning types as visual, auditory, and haptic need to be addressed, and thus, it is of great advantage if different sensory impressions and methods are used in teaching. It is not surprising that it is precisely the combination of different teaching and learning methods that makes it much easier for students to understand and permanently remember the learning content [26].

Maybe, the low results of the inter- and intraobserver reliability of the results of classification systems like AO [27] can be improved, if the teaching of students already focuses on fracture teaching and its classification as part of the learning process. It could be further improved by 3D visualization of not only the fracture but also the classification system itself. In further studies, it might be an option to develop (3D printed) fracture models for the most common classification systems. With the advance of technology and widely available powerful computer systems, as well as the affordable maintenance and use of 3D printers, it is now possible to take this step of transferring and linking knowledge into the third dimension earlier. Furthermore, such learning concepts can be extended easily: for example, in addition to surgical approaches or anatomical landmark courses, the teaching of surgical techniques with real implementation, and use of Kirschner wires, plate- or screw osteosyntheses are also conceivable. By this, there could be points of contact for interested students earlier in their education and raise their interest in a surgical career.

The 3D models printed from PLA show no deformation or change during the course and were disinfected with a disinfectant after each run. Even autoclaving can be used for such models between courses [28]. By this, the models can be used several times and stored for long time without degradation [1].

Although a whole cohort of every student from 1 year was participating, one limitation is the single-center design of this study. However, with evaluation of further courses, not only multicenter studies as well as long-time retention of the learned contents are of particular interest. Another strength of the study is the possibility of increasing the interest of students in the field of trauma surgery and thus attracting young colleagues.

Taking everything into consideration, printing life-sized fracture models gives the advantage of holding and feeling the model with one´s own hand, instead of just looking at it. Taking the fracture fragments apart gives the opportunity to have a look from every angle and understand therapy options, surgical approaches, and screw placement. Afterwards, the fracture can be puzzled together again. Thus, such 3D models should be integrated into teaching of medical students.