Additive technologies in medicine

How to reduce the risks to the health of patients

iQBTechnologies, Habr

In the XXI century, many scientific ideas that once seemed fantastic have been realized in medicine, for example, robotic surgery or bionic limbs. Considerable credit for the recent successes of medicine belongs to additive technologies. Today, models of body parts and prostheses are made on a 3D printer, and in the foreseeable future 3D printing of artificial organs and medicines will become common practice.

According to the Wohlers Report 2018, the healthcare sector occupies 11.3% of the global additive manufacturing market. According to a study by Market Research Future (MRFR), the cumulative annual growth rate of the global 3D printing market for medical devices in 2018-2023 is estimated at 18%.

One of the key factors in medicine is accuracy, because the slightest error in calculations can have fatal consequences. And here 3D printing fits perfectly, because the main advantages of this technology are freedom of design and high accuracy when creating final products. Compared to traditional methods, the possibility of printing unique single or small-scale products with complex geometry opens the way to faster and more economical production.

Advantages of additive technologies for medicine

3D technologies have indisputable advantages:

• High accuracy, allowing to take into account individual characteristics of a person.
• The ability to create structures of any complexity.
• Lightening the weight of printed products.
• Reduction of production time (including due to the lack of equipment), and as a result – acceleration of medical care.
• Saving labor and material resources.
• Reducing the cost of products.
• A large selection of innovative materials.
• Thanks to these features, the equipment can be used both in specialized clinics and in ordinary public institutions.

What can be printed on a 3D printer to increase the effectiveness of treatment

Printing of the following products is practiced:

• layouts of organs, tissues and bones when planning operations;
• prostheses, implants, surgical templates in surgery and dentistry;
• orthopedic insoles, corsets and other orthoses;
• hearing aids;
• master models for medical devices;
• prototypes of medical device cases;
• medical cosmetology products.
• Such an extensive list allows you to speed up and simplify the process of making vital things for patients.

3D scanning and software in medicine

With the help of a 3D scanner, you can get an accurate three-dimensional model of the desired object (bone, dental impression, etc.) in a matter of minutes, then process the data obtained in special software and print the model or finished product on a 3D printer, or make it in the traditional way. At the same time, there is no need to store casts and samples – all 3D models are stored in a digital archive. If necessary, they can be quickly corrected and sent over the Internet to colleagues anywhere in the world.

Planning a successful operation with accurate layouts

Creating accurate 3D models of bones, body parts, tissues or organs allows for a visual demonstration of pathologies on a scale of 1:1. The doctor can accurately assess the size of the pathology and the location of adjacent tissues before the operation. In the case of transplantation, three-dimensional models help to develop detailed and individual operation plans and select exactly the right organs.

A typical example of 3D printing in medicine: a preoperative photopolymer mockup made in our demo room using a ProtoFab printer / Photo: iQB Technologies

A detailed 3D-printed model and its anatomically optimal position help the surgeon in reconciliation at all key stages of the operation. Accurate positioning of pathology and blood vessels in real time makes it possible to increase the efficiency of the operation and reduce risks.

Changing printed anatomical models in accordance with the actual state of organs is one of the most important methods of using 3D technologies. This opportunity not only saves valuable time for surgeons, but also increases the accuracy of disease prediction.

Printing of layouts, models and prototypes made of plastics

Creating customized insoles using the Sharebot Q 3D printer, which helped to achieve excellent results with flexible elastomers that are difficult to use

A productive and cost–effective solution for creating preoperative layouts and models of medical devices is 3D printing from plastics. There are several technologies of plastic printing, including modeling by layer-by-layer deposition (FDM), laser stereolithography (SLA), selective laser sintering (SLS). The first of them uses thermoplastic thread or granules as a consumable, the second uses photopolymer resin, the third uses polyamide or modified powders. 

An FDM, SLA or SLS printer will be a profitable solution for enterprises producing medical equipment: rapid prototyping of device housings using additive technologies speeds up the product development process several times.

3D printing process in medicine

The creation of a printed product takes place in several stages:

1. Patient data collection using various technologies (CT, MRI, ultrasound, PET, 3D scanning).

2. Based on the research results, the target area is selected and a 3D model is created in the software.

3. An exact copy of the object is printed on the basis of the created 3D model.

4. A surgical operation is simulated on the printed model.

3D printing of metal prostheses and implants

For the manufacture of prostheses and implants, different technologies and materials are used – from plastics to metals. 3D printing with metals allows you to create a product with a given complex geometry, ideally suited to a particular patient. Topological optimization solves such important problems for prosthetics as:

• creation of an all-metal structure of any necessary shape;
• weight relief of the prosthesis;
• increasing the strength of products due to microscopic cavities that ensure the migration of the patient's own bone tissue cells;
• creation of prostheses with a porous structure that promotes faster implantation.

3D printing of metal alloys (primarily titanium) is used for prosthetics of the bones of the maxillofacial region, intervertebral discs, collarbones, knee joints, shoulder blades, hip bones. In dentistry, these materials are used for the manufacture of solid implants, as well as metal bases of crowns and bridges made of titanium, cobalt-chromium and other alloys.

The most important features of prostheses created using 3D printing with metals are the perfect accuracy of their connection to the body and the absence of a rejection reaction. Creating prosthetics on a 3D printer is cheaper and requires less time.

Practical application examples

Reconstruction of a malar bone defect using SLM technology

Restoration of a large malar bone defect is a complex surgical operation, during which it is necessary to make the patient's face symmetrical, proportional and anatomically natural. A 43-year-old man went to the department with a severe defect in the left middle zone of the face, which he received 6 years earlier as a result of a car accident. The damaged bone was repaired using an individual titanium implant printed on the additive installation of SLM Solutions. The implant, designed on a computer, had an ideal geometry, and the operation to install it went exactly as planned. Observation of the patient over the next year did not reveal any complications. 

The results of the application of 3D technologies:

• excellent biocompatibility and integration of the bioimplant into tissues;

• reducing the weight of a titanium product by creating its hollow version;

• accelerated integration by filling the implant with material taken from the patient's iliac bone;

• the finished product perfectly fit the damaged area and did not require fitting during the operation;

• complete absence of complications and side effects after implant placement.

Obtaining such results gave hope for the successful use of additive installations in surgical operations.

How the exact model of the spine and trachea was created

The company's specialists share their practical experience of using 3D printing in medicine ProtoFab, which produces a wide range of SLA printers and materials. Representatives of the Third Hospital of Peking University appealed to ProtoFab with a request to create an accurate three-dimensional model of the spine and trachea of the patient to prepare for the upcoming operation. The complications caused by the disease did not allow the surgeon to insert a tube into the trachea to perform the operation. Doctors needed a model with which they could practically evaluate various ways to solve this problem.

Computer and magnetic resonance imaging data were imported into specialized medical software that allows converting all these data into a 3D model. Using this software, ProtoFab specialists were able to see the problem areas of the patient's trachea.

At the next stage, it was necessary to directly perform 3D printing. Such medical projects require the creation of an exceptionally accurate copy with the utmost level of detail. However, stereolithographic 3D printing can easily cope with such complex shapes and structures, and experienced ProtoFab engineers were able to perfectly accurately reproduce everything down to the last detail. The 3D-printed model allowed doctors to analyze an absolutely exact copy of the trachea and the surrounding area before the operation and take preparatory measures that would otherwise be impossible.

Manufacturing of prostheses using 3D technologies

A team of researchers from Chabloz Orthopédie (France) managed to create a unique and truly revolutionary prosthesis. The company worked with Denis Gauthier, who had his forearm amputated. First, specialists performed a 3D scan of the patient's healthy hand using a peel 3d scanner to get its mirror image. This was done so that the designed product perfectly repeats the proportions of a healthy limb. The remaining part of the amputated arm was also scanned to achieve a comfortable and ergonomic fit of the prosthesis.

Denis Gauthier with a ready-made prosthesis

Next, the team started designing a CAD model and developing a myoelectric prosthesis. Batteries, sensor cables and an artificial brush were integrated with the manufactured forearm. The prosthesis itself was developed in CAD and printed on a 3D printer. HP Jet Fusion technology was used to print various components of the forearm. After manufacturing, all the parts were finished and painted.

The use of 3D scanning and 3D printing guarantees not only the correct fit of the device, but also gives complete freedom of movement. A new approach to the design of prostheses allows professionals to develop solutions that have a small weight and are easily customized. Did you know that the parts created on a 3D printer are 20% lighter than their carbon or fiberglass counterparts? Such products also have the necessary rigidity, hardness and durability.

Later, this innovative prosthesis was combined with the BeBionic brush, one of the most advanced bionic limbs, and ultramodern myoelectric forearm and brush were made according to individual parameters. Gauthier's case is an excellent example of the innovative use of 3D measurement and 3D printing technologies.

Hip replacement

The R.R. Vreden Institute of Traumatology and Orthopedics together with LETI (St. Petersburg) carried out work on the creation and 3D printing of a titanium hip prosthesis. On the basis of CT, a plastic mock-up of the bone was created. The next stage is the design of the implant and adjustments for its positioning on the bone. Then, after the doctors had planned the operation on a mock-up, the prosthesis was printed on a 3D printer. The patient, whose hip joint was almost destroyed as a result of the injury, got to his feet.

Corneal seal of the eye

In 2018, British scientists were able to print the cornea on a 3D printer for the first time. Now they can use volumetric printing in the manufacture of the cornea of the eye from stromal cells. They also created special biochernils that consist of corneal stroma cells from a living donor. It also includes collagen and alginates. Protein forms the basis. By placing the resulting substance in the printer, a healthy cornea was printed in 10 minutes, which was viable for more than a week.

This development is very important for the whole world, as this part of the eye can suffer from a burn, infection or injury at any time. Millions of people around the world need a transplant, and they cannot afford it, because there is not enough real donor material.

The technology needs clinical trials, but there is hope for mass printing of the cornea of the eye.

3D printing of vessel models

Blood vessel and aneurysm models

The most important role for the full embolization of intracranial aneurysm is played by the stable position of the microcatheter and its optimal shape. With the help of a 3D printer, models of a blood vessel and aneurysm can be printed, which will help the surgeon better understand the anatomical structure. The correct formation of a microcatheter for intracranial aneurysm is a complex process, and doctors who encounter this technique for the first time need long–term training. For a visual demonstration of blood vessels and aneurysms, you can use a life-size model printed on a 3D printer.

3D-printed models for operation simulation systems realistically display a complex system of blood vessels

In comparison with models of vessels made of ABS plastic, silicone models more accurately correspond to human blood vessels. 3D printing allows you to "copy" the complex geometry of the heart of patients with cerebrovascular diseases and instantly transfer information to the software.

Additive manufacturing of templates

Traditionally, X-rays are used to plan an osteotomy. However, two-dimensional images do not reflect the actual condition of the bones. In this regard, 60% of operations do not give a positive result. 3D templates printed by Materialise will help solve this problem. The production of such templates does not require large costs, and they are available to all patients.

On October 26, 2019, iQB Technologies and our partner TWIZE took part in the medical conference "Live Arthroscopic Hip Surgery" at the V.M. Buyanov State Clinical Hospital. We presented preoperative layouts printed on ProtoFab photopolymer 3D printer based on computed tomography data.

The relevance of 3D modeling in the future

Thanks to the innovations described in this article, it is possible to increase the reliability of operations, save time, reduce production costs and the cost of final products, and most importantly – improve and prolong the life of patients.

In recent years, more and more attention has been paid to 3D printing in medicine and its advantages - high accuracy, performance and customization possibilities. Along with the improvement of 3D equipment, active work is underway to create new materials for medicine. With the help of additive technologies, it will be possible, for example, to directly print ceramic products, as well as to create whole dentures, including teeth and gums, from biocompatible materials.

The direction of modern medicine, which is associated with a breakthrough in the treatment of diseases and pathologies in the foreseeable future, is 3D printing of tissues, blood vessels and organs, or 3D bioprinting. Leading scientific and medical centers develop new technologies and conduct clinical research in this area.

The achievements of additive and biomedical technologies will contribute to the development of bionic modeling and 3D printing of tissues and organs, which will preserve health and save the lives of a huge number of people.

Assistance to the 3D industry during the coronavirus pandemic

Many companies support medical institutions during the COVID-19 pandemic. Suppliers of medical equipment cannot cope with the load, especially due to protective equipment (respirators, masks, screens). All over the world, 3D printing has begun to provide real help, expressed in the production of a prototype valve that is installed in a respirator. Lonati SPA supplier in Italy was able to print the valve from PA12. The productivity was from 100 pieces per day, and the price was minimal.

In the UK, many manufacturers have switched to manufacturing equipment for lung ventilation. One of the companies manufactured parts from metals and polymers, which helped in the production of clamps, fasteners and housings. Thanks to laser sintering technology, dozens of parts that do not require processing can be produced simultaneously.

ProtoFab has developed a protective mask made of high quality soft polypropylene. It has a special design that separates breathing through the mouth and nose, is convenient to use and resistant to any temperature. Thanks to replaceable filters, the mask will last a long time.

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