**1.1 Materials**

Depending on the type of orthosis, the location of its action, the type of treatment, a combination of different materials (metals, plastics, leather, composites, foams, rubber and other materials) is chosen. The material is often selected to achieve the desired clinical result, while guaranteeing the required technical strength and environmental resistance [3, 10].

The choice of material for a given design depends in part on an understanding of the basic principles of mechanics and materials, force concepts, deformation and failure of structures under load, improving the mechanical properties by heat treatment, the manufacturing process and also has an impact on the proper functioning of the orthotic device. Among the traditionally used materials we can mention metals (connecting materials), they are also plastics, textiles, rubbers and leather have a wide range of uses. Development of new materials, especially the possibility of using new composite materials (plastic matrix with reinforcing fibers), which provide better mechanical properties and aspects of biocompatibility [3].

When using plastics, a distinction is made between low and high temperature plastics, while their use depends mainly on the location for which the orthosis is intended and the purpose of its use. In the area of the forearm and hand, lowtemperature thermoplastics are usually sufficient, which can be modeled directly on the patient's body surface after heating to the working temperature (60 to 70° C). Especially orthoses intended for the fixation of affected joints, it is suitable to use either high-temperature thermoplastics, or low-temperature thermoplastics, but with a greater thickness (3.2 mm). These types of upper limb orthoses are also produced by lamination, but they are mainly those that are intended for long-term application in permanent disabilities. Large progress is being made mainly due to the wide range of materials currently available to the orthopedic technician. The ability to produce custom devices with very complex accuracy has improved the customization of the devices. Materials with a high strength-to-weight ratio have made the equipment lighter and materials that bend smoothly have improved achievable functions and performance. Knowledge of materials helps the technician in the production process and in the use of new techniques, such as additive production. As technologies and materials are constantly advancing, it is important that the orthopedic technician is constantly informed about innovations, technological procedures and materials, so that he can provide the patient with adequate care for progress [3].
