Can 3D printing give a new lease of life to anatomy teaching?
Can it make it more accessible and affordable?
- By: Christopher Tattersall
Anatomy underpins almost every medical interaction, but teaching of the subject has changed little over the centuries and it has seen a decreasing presence on medical school curriculums. As a result, many medical students are beginning their postgraduate training with below par knowledge of anatomy. This could be about to change, however, as new technologies, most notably “additive layer manufacturing” (or three-dimensional (3D) printing), help improve the teaching of anatomy and make it more accessible.
The study of human anatomy can be traced back to Ancient Egypt in the text of the Edwin Smith Papyrus, where traumatic injuries were described on the basis of anatomical relations. To begin with, however, anatomy teaching was born more out of art than science. Leonardo Da Vinci is said to have learnt anatomy from the Italian artist Andrea del Verrocchio, and it was in the drawings of Da Vinci where the study and appreciation of human anatomy began to take shape. The first modern anatomy textbook soon followed. Andreas Vesalius published De humani corporis fabrica in 1543, using printing press technology to disseminate his drawings widely. The popularity of studying and understanding the form and function behind human anatomy began to grow. In 1594, the first anatomical theatre for observing dissections opened at the University of Padua, Italy.
Fast forward to 2014, and our understanding of human anatomy has grown exponentially. Yet, most tools used for anatomy teaching are still textbooks and dissections and prosections of cadavers. The hand drawn sketches of Da Vinci and Vesalius have long since been replaced by graphical representations and radiographic images, which aim to describe accurately the “normal” anatomy, relations, and key features. To show what the actual anatomy looks like, textbooks often use photographs of formalin fixed dissections. However, specimens may fade or lack colour and therefore fail to give a true sense of anatomical relations and proportions. Students also use commercially produced plastic models, which often represent a highly idealised view of anatomical structures and have limited application beyond basic understanding.
Access and training
To gain an in-depth understanding of anatomy, there is no substitution for hands-on experience of dissection or prosection of cadavers. But unless you are a student at one of the decreasing number of medical schools that still offer this learning opportunity, access to cadavers can be problematic. Currently, 10 of the 35 UK medical schools offer dissection on their undergraduate courses (of which three offer full body dissection), and seven universities instead offer prosection.
Access to cadavers has declined for several reasons. Legislation such as the Human Tissue Act 2004 requires formal, witnessed consent to bequeath your body to medicine. This can be time consuming and expensive to administer, meaning few people take up this option. Ed Fitzgerald, a registrar in general surgery in London and a past president of the Association of Surgeons in Training, said: “One of the big factors is costs and resources. The cost of having the license, of the facilities, maintaining the labs, and the cadavers themselves, is an expensive option for medical schools.”
The lack of opportunities to learn anatomy through dissection at medical school has led to concern from the Royal College of Surgeons, who have said that a lack of anatomical teaching could see a shortage of surgeons in the United Kingdom. In the past two years, training posts in Britain have remained unfilled because many candidates lacked the minimum standards required. Vishy Mahadevan, professor of anatomy at the Royal College of Surgeons, told Student BMJ he is “very concerned” about the current status of anatomy teaching at UK medical schools. “Whereas anatomy was once rightly regarded as essential and of crucial importance to the study of medicine, the time allocated to its study in the present day is substantially and worryingly less than in the past. We are seeing an increasing number of qualified doctors in their early surgical training who do not feel confident in their clinical abilities, and they often attribute this to an inadequate understanding of anatomy,” he said.
A potential solution to the lack of access to cadavers arrived in the late 1970s courtesy of Gunther von Hagens, whose “plastination” techniques preserved anatomical prosections by replacing the perishable tissues with a plastic resin. This enabled life-like specimens to be stored and handled without the need for specialist equipment. Richard Tunstall, head of clinical anatomy and imaging at Warwick Medical School, has found the plastinations to be a useful teaching tool. “Both the dissection quality and presentation of the specimens is of the highest standard, making it easy for students at any level to visualise core anatomy,” he said. “The robust, dry, and odourless nature of the specimens enhances their appeal as a learning tool and enables students to quickly engage with the material.” There is a trade-off, however, as the plastination process can alter some structures, particularly the more delicate features, such as some of the finer neurovasculature and lymphatics. Also, the specimens are expensive, with Warwick paying £400 000 (€552 000; $585 000) for their set of 200 plastinations.
More recent advances in printing may hold another solution in terms of making anatomy teaching more accessible and affordable in medical education. Bespoke prosthetics designed to fit an individual patient have been produced by 3D printers. In 2013, Student BMJ reported on how this technique was being used to produce mandible replacements and craniostomies, saving valuable time in surgery. In the same year, Warwick’s medical school teamed up with Warwick Manufacturing Group to experiment with making translucent 3D printed models of the heart, on the basis of Leonardo Da Vinci’s 3D sketches from more than 500 years ago. The translucent models were displayed in an art exhibition, Leonardo Da Vinci: the Mechanics of Man, in the Palace of Holyroodhouse, Edinburgh. Warwick Medical School then teamed up with Monash University, Melbourne, Australia, to explore techniques to use 3D printing as a tool in anatomical and surgical training. Advances in 3D printing technology mean that models can now be scanned and printed in a variety of colours as well as in translucent materials to create a new generation of anatomy teaching tools.
Tunstall says they set out to solve two problems. “The first is to enable anatomical and surgical training using specimens in any location worldwide. Currently the use of human tissue in teaching and skills training is highly regulated, subject to a relatively restricted supply, restricted within certain cultures, and can only be performed in licensed areas. 3D printing anatomical specimens using man made materials will circumvent these issues,” he said. “The second is to enable surgeons to practise or carry out preoperative planning for difficult or rarely seen procedures. Patient scans can be 3D printed and a database of pathology built to enable enhanced training.”
Printing a 3D model
So, how do you construct a 3D model in full colour? The relevant anatomy is scanned, using x ray computed tomography or magnetic resonance imaging. When producing models for teaching purposes it is possible to increase the level of detail in the anatomy being scanned. By scanning cadaveric tissue, scans can be carried out at a much higher power than in living patients because the risk of exposure to x rays is minimised. The result of this scanning process are “slices” that are microns thick, rather than millimetres.
The images generated from the scan are then segmented and the data within the image files are coded, so that each individual tissue type can be identified. By identifying tissue types this can then be translated into whole structures and organs. The dataset is able to differentiate an artery from a vein, kidney from adrenal gland, spinal cord from vertebrae, and so on. What is left is an extremely detailed 3D dataset ready to be sent to a colour 3D printer. This can produce a bespoke, accurate, coloured anatomical replicated model. These models are able to show muscle, vasculature, nerves, and organs in true to life scale and colour, with anatomical relations easily appreciated.
Detailed 3D printing can produce models with pathological features on a wide scale, transforming basic education in clinical anatomy. Students are able to hold a printed “normal” heart in their hands and can readily compare it with a heart that has, for example, left ventricular hypertrophy, Tetralogy of Fallot, or an atrioventricular septal defect. Textbooks have representations of these and there are some formalin held specimens in some medical schools and museums. But allowing students to examine an accurate representation of this anatomy can help them to identify where the malformation is and get a true feel as to how it would affect function and surrounding structures.
The second main area of benefit is in surgical training. Surgeons are able to practise techniques on cadaveric tissue before they operate on patients. Mr T Singh, consultant otolaryngologist at Southampton NHS Trust, has been testing surgical techniques on the printed models. “I think it is a good starting point. At the moment, the features on the models are only superficial, becoming amorphous on drilling. Despite this, they are close but not quite matching human material. I am hopeful that later generations will improve the internal detail.” Training on printed models could mean less wastage of valuable cadaveric tissue. Singh added that 3D printing could also offer students the ability more readily to “appreciate 3D topographical relationships of nearby microstructures.”
Use of 3D printed models may reduce training costs and enable many more health professionals to undergo training. Procedure training will also be possible outside licensed premises. The costs of printing a small to medium model—for example, the temporal bone—are as little as £50-200, compared with the tens of thousands of pounds that courses using cadavers cost. Surgeons will also be able to study microanatomical features by enlarging these features before printing them—for example, tiny ossicles and tarsal bones.
Like many new advances, the barriers to rolling out this technology globally are likely to be technology and time. Most medical schools in the UK have access to 3D printers capable of printing in colour, but currently the main obstacle is time to prepare the materials. It can take 8-10 hours to print a basic model.
This is just the beginning for the use of 3D printing in this field. The next step is manufacture of printed models made from several materials, which will allow features to be more flexible so the user can move them. For example, a trainee surgeon could move an artery to reach deep to it, as you would in surgery. This method will also allow the printing of coloured material within transparent material. You could create a transparent skull showing the routes of the cranial nerves, or a transparent foot showing the positioning of the metatarsal and tarsal bones. This has already been produced by the Monash-Warwick collaboration.
We can also expect to see the use of 3D printed models to teach anatomy in areas of the world where cadaveric tissue is not available, for reasons of cost and storage or ethical, cultural, and legal barriers. This technology offers a solution for college and medical students in poorer areas of the world to be able to study actual anatomy (normal and pathological). It will also give surgeons the chance to develop their skills in a safe and controlled environment relatively cheaply. This could have the potential to save lives and improve outcomes.
Tunstall believes further exciting developments in this field are close by. “Future developments will focus on the use of a new generation of multiple colour and multiple material printers to generate more realistic specimens that use different materials for the body tissues. This will enhance a student’s ability to interact with the 3D printed specimens and is essential if the prints are to be of use in surgical training.” Leading anatomical model companies are showing an interest in the work being done in this area. We can expect the field to become commercialised soon, making these models affordable for individual students.
This innovation presents a leap from the formalin held dissections in terms of detail, perspective, and anatomical relations. Above all, 3D printing enables relatively quick bespoke reproduction of anatomy rather than simply providing often a stylised view. This technology promises to widen access to anatomical teaching materials as well as a more immersive way to learn about anatomy and various pathologies.Christopher Tattersall, second year medical student
1University of Warwick, UK
Correspondence to: firstname.lastname@example.org
Competing interests: None declared.
Provenance and peer review: Not commissioned; not externally peer reviewed.
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Cite this as: Student BMJ 2015;23:h1930
- Published: 29 April 2015
- DOI: 10.1136/sbmj.h1930