Abstract
Venous leg ulceration is a common problem throughout the western world. The chronic nature of venous ulcers creates considerable demands upon all healthcare authorities in terms of treatment costs and nursing resources. Compression bandaging is considered as the “gold standard” for managing venous leg ulcers and treating the underlying venous insufficiency. The main function of a compression bandage is to exert external pressure onto the limb. The ability to generate and to maintain this sub-bandage pressure is determined by the bandage structure, the elastomeric properties of the yarns, as well as the finishing treatments applied to the fabric. Non-woven materials are currently used in combination with compression bandages in an attempt to evenly distribute pressure and provide protection over bony prominences of the leg (tibia). However, these multilayered bandage systems are uncomfortable to wear due to their bulkiness and undesirable thermo-physiological characteristics. They are also difficult to apply and are associated with relatively high costs due to the requirement for specific bandage types for each layer. The requirement for a single-layer compression bandage that incorporates the performance characteristics of multi-layered compression bandage systems is of paramount importance.
Three-dimensional knitted spacer fabrics are becoming increasingly important for developing novel medical textile products. In comparison to traditional woven or knitted fabrics, the range of physical and thermo-physiological properties which can be achieved is considerably wider. These novel structures consist of two independent faces with interconnecting threads joining them. They can be exceptionally soft, incorporate large volumes of air, and provide good resilience to compression, temperature control, and moisture management. The layer of air that lies between the two independent textile faces creates a comforting, climate-controlling effect which prevents sweating and overheating of the skin. Spacer fabrics also provide an excellent cushioning effect which means that there is no need to use multiple layers of padding and compression bandages. When elasticated yarns are incorporated into the spacer fabric structure it is also possible to produce similar pressure-generating characteristics to those of traditional compression bandages.
The focus of this paper is to discuss the design criteria and important functional properties of three-dimensional single-layer compression systems. A range of both weft and warp knitted spacer-fabrics were tested in order to determine their basic functional properties. Mechanical testing was also undertaken in order to assess the elastic and elongation properties of these spacer-fabrics. Load elongation hysteresis is important since it not only relates to the materials ability to generate external pressure, but also how this pressure maybe affected from any changes in tension, extension, and elastic properties. The tension, and hence external pressure, generated within traditional compression bandages normally decays slowly over an extended period of time after application onto the limb. The tension decay test simulates bandage application and highlights a materials ability to sustain tension throughout a pre-determined time period (15hours).
Thermo-physiological and climate-controlling properties of the spacer-fabrics will also be discussed in this paper. These tests directly relate to the functional comfort characteristics of the spacer-fabric structures which include thermal resistance, thermal absorpitivity, water vapour permeability, and evaporative heat loss. In all of the tests undertaken, comparisons are made to results obtained for traditional compression bandages and padding bandage materials.