**1.2 Fabrication**

#### *1.2.1 Conventional production of orthoses*

Upper limb orthoses are manufactured using plastics, while the production of low-temperature and high-temperature thermoplastics has a significantly different technological process. With low-temperature thermoplastics, processing is faster and easier. A shape is cut from the plastic or cut out according to the choice of the orthosis, which is then heated to a temperature of 60 to 70°C (depending on the thickness of the material and its properties). The material can be heated to the operating temperature in either a water bath or by dry heating. After isolation of the patient's body, the plastic is formed directly on the limb, where the knowledge and experience of an orthopedic technician are necessary for the final position of the segment of the affected segment to be correct. Gypsum positives are used as a basis for the production of orthoses from high-temperature thermoplastics. However, before starting the plastering itself, it is necessary to fill in the measurement sheet. For an orthopedic technician, it is important to assess the range of motion in terms of mobility in a targeted way to create a design for a functional orthopedic device. Based on the initial examinations, the maximum correction position of the given segment is assessed. According to the required function of the orthosis, the maximum correction position of individual segments and its time tolerability are determined. If the joints are physiologically loaded, the properties and construction of the orthosis must not change this loading situation. When plastering in practice, plaster bandages are most often used, which are attached to the limb that will be plastered and shaped at the same time. It is important to pay attention to the load points and correct the shape before the plaster hardens. It is also very important to draw landmarks and painful areas on plastered parts of the body. When removing a plaster cast, it is very important to note and mark all bone growths (bumps) that protrude to the surface or are well palpable under the skin, as some of them are important landmarks. They are marked with a dermo-graphic pencil so that they are well pressed onto the gypsum casting. Although the casting itself is in principle accurate, if the patient moves or adjustments are not made correctly, this will affect the shape or function of the orthosis. This is the case when the skill of an orthotist is shown. With the gypsum positive finished, it is necessary to decide whether to use a high-temperature thermoplastic or to make the orthosis by lamination [5, 11].

The techniques used to make traditional metal and leather orthoses and thermoplastic orthoses have not changed. What has changed is where these devices are made and whether they are made for a specific patient or mass-production. In the search for production efficiency and cost savings, along with the limitations of established production technologies, many prosthetics manufacturers have chosen the "multi-model for all" approach. They basically create several different standardized sizes and a neutral look (in terms of color, texture, etc.). Using these so-called stencils, thousands of aids are produced every year.

Due to developments in data collection and software development, the use of computer-aided design (CAD) and computer-aided manufacturing (CAM), including additive manufacturing (AM), has increased for orthoses. At present, CAD/ CAM methods are available for the smallest orthotic workplaces and can be used to speed up assembly as well as to facilitate off-site production in a specialized production center [5].

In order to achieve the optimal clinical result of the application of orthoses, it is necessary to make compromises in the field of choice of materials and individual components from which the choice of production method and assembly is derived [3, 8].

#### *1.2.2 Innovations in the technological process of orthoses production*

The innovation of the technological process of making an orthosis may consist in the use of modern technologies in the collection of measurements and subsequent conventional production or in the modernization of the entire process of data obtainment or production. The innovation of the technological process of collecting measurement data consists in the use of 3D scanning and computer processing of scanned data into a 3D model, which replaces the gypsum positive and the subsequent use of subtractive or additive methods of positive production. In this way, we get the basis either for drawing high-temperature thermoplastic or for the following

#### *Orthoses Development Using Modern Technologies DOI: http://dx.doi.org/10.5772/intechopen.95463*

lamination process (conventional production). The innovation of the entire technological process of orthosis production also consists in digital sampling of measuring data (3D scanning) and subsequently a specific shape of the orthosis is designed in the relevant software, which is manufactured using additive technologies. Due to the cost of the purchase price of digital imaging equipment and subsequent subtraction or additive production, large companies provide the possibility of external design and production of aids, while the orthopedic technician takes the appropriate specified measures necessary for production. The process of obtaining measurement data for "branded", i.e. the orthoses patented by the manufacturer, has been simplified by using developed measuring tools. Their use in practice is conditioned by the training of the staff who gather these measurements and their use reduces the risk of error in production. This increases the adjustment and function of the orthoses and reduces the number of aids that need to be redesigned. Despite many advances in materials and manufacturing techniques, clinical judgment and the technical skill of the orthopedic technician in the conservative treatment of the patient remain the most important elements in creating a well-equipped, highly functional orthosis [3, 5, 10].

The modern approach to the creation of devices begins with the digitization of the human body and its parts in order to obtain input data from the patient's body for the needs of modeling an orthopedic device in CAD software, following its final production. In the hands of experts, this innovative method replaces the unpleasant and time-consuming plastering. Thanks to this technological process, it is possible to achieve greater accuracy, speed of device production, a new level of comfort for the patient and functionality for the field of ortho-prosthetics. Two techniques are used for data collection: measurement and scanning. The data is processed by a computer program that creates a three-dimensional image of the model. The technician then converts the data and image to adjust the positive model. Software tools allow the practitioner to accurately apply a wide range of adjustments, including bends, rotations, scaling, alignment, and adding pressures or reliefs [5].

Digitization brings to the system of orthopedic practice better control over the creation of the device and at the same time respects the know-how of the traditional method of production and the creativity of the orthopedic technician.

In general, digitization allows:


Most of the software used for the design of orthopedic aids use features such as templates and macros (pre-recorded sequences of adjustments) of selected orthosis designs, which further speed up design work and ensure consistency. Other features focus on the design of the final device, not just the positive form. The information is exported to a CAM machine, which is used to manufacture a modified positive model that will be used to make the orthosis [5].

The creation of digital models also brings other possibilities how to analyze possible problems that may arise as a result of design, choice of material and in connection with the production process. The computer definition of the product to be manufactured includes all dimensions and material [3, 10].

The production of positives by the subtraction method can be realized by means of multi-axis milling machines and robotic arms. The control of multiple milling cutters is simpler, but it is possible to produce mostly only less complicated shapes, which means that they are suitable for the production of models of the forearm, shoulder, or elbow joint, but not detailed models of the hand and fingers. There is a need to use robotic arms that can incorporate even the details of the positive. The semi-finished model for production can be gypsum or polyurethane blocks of material, of different sizes depending on the location. Polyurethane blocks are usually produced in different densities according to the purpose of subsequent use.

Although CAD/CAM production is currently widely available, high initial costs (scanner, software, milling machine, 3D printer) limit its use even in small orthopedic and prosthetic operations. This leads to the centralized production of orthotic devices, but it also brings limitations in the use of this technology. This also leads to new problems arising from the fact that the experts themselves do not have control over the actual construction of the equipment, as this is done by technicians at a remote production site [10].

A general feature of additive manufacturing (AM) methods is that the production is not carried out by removing the material as in a milling machining, but by gradually adding the material in the form of powder or melt in small layers. The basic principle of 3D printing is that the computer interpretation of the object serves as a direct input to the 3D printer, which creates the required physical object without special tools [12].

Thanks to AM, it is possible to produce such products that are otherwise unusable, or their price would be very high. For parts manufactured by AM, the complexity is not what the final price is based on, it is mainly based on the material used and its properties and accuracy of 3D printing. The second big advantage is production without molds and tools. The third advantage is the possibility of production from demanding, problematic materials.

There are several ways of 3D printing, which differ in technology, materials used, print speed, accuracy and strength of products or price.

At present, various 3D printing technologies are available, with material extrusion and SLS technology having the greatest application and use in the field of prosthetics and orthotics.

FDM (Fused deposition modeling) is the most common and widely used 3D printing technology today. It is an extrusion 3D printing, in which models and prototypes are formed by layering step by step from various non-toxic thermoplastic materials. The plastic fiber is guided to the printer head, where it is melted and applied in layers that gradually solidify.

The material used in the SLS (selective laser sintering) and SLM (selective laser melting) printing methods is in the form of a powder (plastic, metal, ceramic or glass powder). The printer applies a layer of powder material to the substrate by means of a built-in roller, over which a laser (for example a laser based on carbon dioxide) moves, which selectively welds it into the lower layer. Subsequently, the roller applies another layer of material until a complete 3D model is created. The resulting models are characterized by high strength.

Orthoses made with additive technologies require postprocessing, which most often consists of surface treatment (roughness, appearance, polishing, painting, painting, etc.), which differs depending on the technology used. With FDM technology, it is advised to smooth out the layers that remain present to the print to a greater or lesser extent. The need for postprocessing in the case of SLS printing is significantly reduced compared to FDM technology.

*Orthoses Development Using Modern Technologies DOI: http://dx.doi.org/10.5772/intechopen.95463*
