## 2 Classification of Compression Garments and Specific Requirements

Table 2: Main groups of wearable compression products. prevent injuries [23]. It is found that swelling, power, and strength are improved during recovery with compression garments [4; 22], and the efficiency of compression garments is affected by garment construction, fabric properties, garment fit and positioning on the body. All these factors play a significant role in the predictive pressure value generated by the compression garment and may undermine its functionality [24]. Functional products for medical purposes have to fulfil the following requirements: (a) to match individual characteristics of the product, size and duration of usage; (b) to perform appropriate physical, chemical, medical properties to ensure compliance with the required functions; (c) to preserve geometrical dimensions and shape as well as functional and physio-mechanical properties under the influence of the biological environment; (d) not to cause skin irritation, pain, discomfort, etc. ; (e) not to decay and thus not release any harmful toxic substances; (f) to maintain the geometrical shape and dimensions after sterilisation and washing; (g) to maintain physical, mechanical and additional functional properties in long-term usage. The listed requirements are applied to all kinds of medical products, however, there are additional specific requirements for only orthopaedic compression products. Medical orthopaedic supports must also comply with the following requirements: (1) to match individual limb dimensions; (2) to evaluate the biomechanical state of muscle; (3) to ensure the required compression; (4) to preserve the geometrical shape and compressive properties during long-term usage; and (5) to preserve dimensions and compressive properties after washing [25; 26]. Compression therapy is usually applied for bandaging, compression stockings and orthopaedic compression supports. According to previous studies, it is proved that the blood flow is faster under gradual compression with an average compression rate of 25 mmHg [25; 26; 27]. Properly used compression therapy may result in a promotion of healing of leg veins, injuries, and burn wounds and increase the life quality. Improperly applied compression therapy may cause long-term (delayed) healing, pain, traumatic ailments, or even loss of the limbs [28]. In the case of untreated venous diseases, it progresses and pain develops, and dangerous complications such as inflammation of the veins, eczema, thromboembolism, ulcers, or varicose vein thrombosis bleeding may appear [28; 29]. Compression garments for venous diseases are among the best-known and the largest application areas of compression therapy for medical purposes. Venous diseases are very common in developed countries--about half of the adult population consults their doctors about problematic leg veins at some stage during their lives, and 10-20% of the population suffer from varicose veins [2; 17; 30; 31]. In the case of medical requirements, it has to ensure the required compression level. In European countries, compression garments are classified into four groups according to the compression intensity. The lowest compression values are used for prevention or marginal ailments, while higher compression values are applied for patients complaining of major diseases. The differences between compression groups' valuations in different countries are presented in Table 3. Different scientific papers and standards refer to the different recommended values of compression at the ankle [32; 33; 34; 35; 36] (compression measurement at the ankle describes the compression class of compression socks, it ranges from 10 mmHg (according to the French standard ASQUAL [37]) to 21 mmHg (according to the German standard RAL-GZ 387/1: 2008 [38])). However, it is recommended that the compression should not exceed 40-50 mmHg. Moreover, the highest compression has to be applied to the ankle and calf and, rising to the top of the product, compression has to decrease gradually: ankle zone--100%, calf zone--70%, above the knee--50%, thigh zone--40% [30].