Lymphedema is a condition brought on by impaired lymphatic drainage that causes chronic inflammation in the body’s tissues. The affected areas of the body swell, change in size and shape, resulting in irreversible damage to lymphatic vessels. Management of limb swelling involves a variety of approaches intended to reduce localised swelling, including a specialised form of massage (manual lymphatic drainage) and the use of compression bandages and hosiery1 2. In order to successfully contain swelling, hosiery should be made from high compression, low stretch materials and applied to give a graduated pressure3.
Flat and circular knitted fabrics in compression garments
The way in which a compression garment exerts pressure on the skin is achieved through a combination of factors, such as, the complex interactions of the physical properties and construction of the hosiery, the size and shape of the limb to which it is applied, and the activity of the wearer.4 By adjusting the type of yarn used and the method by which it is knitted into the fabric, it is possible to alter the level of compression of the final product. Compression garments are produced using two main knitting methods- flat knit and circular knit. Each design is used for a wide variety of therapeutic applications.
Flat-knitted products are recommended for use in lymphatic therapy, where they can be customised according to individual patient’s anatomies. As the name suggests, the flat-knit method produces a flat piece of fabric that has been knitted row by row. Production of garments involves multiple stages and allows for stitches to be added or removed at any time during the process. The material in flat knit compression stockings is a relatively low stretch and has a high working pressure, which means they exert a high pressure on the tissues. This knitting technique is most commonly used in custom-made compression garments, as it renders a ‘stiffer’ fabric that adapts to shape distortions very effectively. For this reason, they are the compression garment of choice for lip- and lymphoedema (Medi, 2017).
In contrast, Circular knitted products are ideally suited to patients with venous disease and require much less work to produce them. The machines used to knit these garments use a fixed number of needle’s that are aligned in a circle, which gives a tube design. The range of sizes and shapes that can be accommodated is less than in flat-stitch garments. However, some shape variation can be produced during knitting by altering the tension of the inlay yarn and, to a lesser extent, by varying stitch height (Lymphedema Framework, 2016). Most commonly found in ready-made garments, circular knit products have a higher degree of stretch and exert less pressure on the tissues compared to flat-stitch garments.
The fabric that is used for both circular and flat-knit garments is constructed by two interwoven yarn systems. The body yarn determines the thickness and stiffness of the garment, while the inlay yarn determines the grade of compression.
Which type of knit is better for Lymphedema?
At this point in time, there is no current research that fully endorses either flat or circular-knit as the ‘best choice’ for Lymphedema patients. This is because Lymphedema management is not a “one-size-fits-all” approach and it’s impossible to say that one type of compression works best for everyone. Each case of Lymphedema is unique to the person who lives with it and the range of needs and anatomical differences in the community is huge! Therefore, compression care needs to reflect this and garments must only be prescribed by a Lymphedema therapist who accurately identifies each person’s individual condition and needs.
In saying this, current research findings have shown that flat-knit (custom-made) garments have certain advantages over circular-knit in the management of Lymphedema. This is due to a number of reasons: the yarn used to construct these garments is low in stretch and exerts a higher pressure on the tissues than circular-knit, they can provide different levels of pressure at various sites in the same garment and they have a stiffer feel to them which helps contain the edema better. Flat-knit garments can suit a much wider range of shapes and sizes and are suitable for all stages of Lymphedema swelling.
In milder stages of Lymphedema, circular-knit (ready-made) garments can be an effective solution for managing swelling. As they are thinner and easier to don, they can be more suitable options for people who are elderly, have arthritis or are disabled. For example, it may be easier for a person with reduced strength abilities to layer two ready-made garments than don a tight custom-made garment. When the stage of Lymphedema is moderate to severe and limbs begin to change from their regular shape, ready-made garments may not be appropriate due to their tendency to dig into skin folds, tourniquet and can damage the skin. These days, ready-made garments are available in a bigger range of choices, including flat-knit ready-made items, however, the current research findings do still lean in favour of custom-made for Lymphedema management.
1. Földi E, Földi M, Weissleder H. Conservative treatment of lymphoedema of the limbs. Angiology 1985; 36(3): 171-80.
2. Ko DS, Lerner R, Klose G, Cosimi AB. Effective treatment of lymphedema of the extremities. Arch Surg 1998; 133(4): 452-58.
3. Regnard C, Allport S, Stephenson L. ABC of palliative care. Mouth care, skin care, and lymphoedema. BMJ 1997; 315(7114): 1002-25.
4. Clark M. Compression bandages: principles and definitions. In: European Wound Management Association (EWMA). Position Document: Understanding compression therapy. London: MEP Ltd, 2003; 5-7.
Lymphoedema Framework. Template for Practice: compression hosiery in lymphoedema. London: MEP Ltd, 2006.
Medi (2017): http://mediusa.com/