“Circular knit is always worth a try”

What are the differences between circular and flat knit medical compression stockings? Which version is suitable for what type of patient? These and other questions about compression therapy are answered by Prof. Dr. Markus Stücker, Director of the Clinic of Dermatology, Venerology, and Allergology in Bochum and Senior Physician at the Vein Center, Departments of Dermatology and Vascular Surgery in Bochum.

Prof. Stücker: Compression therapy is the foundation for all phlebological and lymphological treatment. Using circular or flat knit compression stockings is an essential part of this treatment. The knitted fabric versions differ in stitch size and number of stitches. Circular knit stockings are made in circular knitting cylinders. The number of stitches is identical in all areas of the stocking. This means that we have exactly the same number of stitches around the ankle, which is typically the narrowest part of the leg, as in the area of the thigh. An increase in circumference is achieved by changing the size of the stitches. This means that there is an automatic limitation, for example with big jumps in caliber. Flat knit stockings are produced in series on a flat machine. The textile is closed with a seam, thus becoming a stocking. Changes in circumference are achieved by adding or removing stitches. In this way, even irregular leg shapes can be covered. Flat knit compression stockings also feature higher stiffness and are therefore a good option to treat indications that require strong, durable compression, such as lymphedema or lipedema.

Prof. Stücker: A circular knit stocking is a standard stocking, which is highly suitable for most patients with chronic venous insufficiency. Circular knit is therefore always worth a try, representing a useful treatment option where it works. There are, however, two specific situations where a circular knit stocking will not work. On the one hand, this includes big jumps in caliber, as mentioned previously. We refer to this when there is more than one centimeter circumference for one centimeter in length, i.e. there are actual steps in the leg. The other situation is when the thigh is much more voluminous than the ankle. In general, the following applies: if the circumference of the thigh exceeds the circumference of the ankle by 2.5 times, circular knit can no longer provide the required fit. That is when flat knit is needed, with a stitch quantity adapted to the patient’s anatomy.

Prof. Stücker: When the patient is suffering from primary lymphedema with swelling in the area of the toes and foot, sufficient pressure cannot be achieved with a circular knit stocking, particularly around the instep. Flat knit stockings are much more beneficial here because they generate a good massage effect during movement even with moderate contact pressure, thanks to their higher stiffness. And this comes into effect particularly in these difficult areas. The massage effect is essential especially with lymphedema. During early stages, we can sometimes try with a circular knit stocking. But as soon as toes and feet are also affected, there is generally no way around flat knit. This also applies to other indications, such as extremely obese legs with pronounced differences in circumference or advanced chronic venous insufficiency with lipodermatosclerosis or other deformities in the area of the lower leg – a circular knit stocking doesn’t usually suffice there, either.

Prof. Stücker: These additional features are incredibly useful because they often allow treatment of complicated leg shapes in the first place and ensure effectiveness. Without additional features, a flat knit stocking can usually not be adapted in a way that makes it suitable to be worn compliantly by patients. There are more than 1,000 combination options of product versions and additional features so patients can be treated individually. This means, of course, that you can’t note all the required additional features on the prescription. In these cases, trust-based cooperation with a medical retailer working with an order pad for custom-made products is all the more important. For physicians, it’s generally a good idea to follow the suggestions given by the medical retailer when it comes to necessary additional product features. Compression products with additional features also require a specific measurement process for which medical retailers are trained especially.

Prof. Stücker: First of all, the goal has to be clear: patients should feel better when wearing the stockings than without. You shouldn’t just insist on a high compression class if Class 1 provides relief and the patient enjoys wearing the stocking. Dialog and treatment compliance are key. Patients who are happy with Class 1 will be more willing to try higher classes later, if this becomes necessary. It’s also important to make patients aware that they need to use the product in the long term, and that skin irritation is the most common complication. About 50 percent of patients complain about itching under the compression stockings. This is caused by mechanical rubbing, not by allergies. The need for skin care must therefore also be pointed out early to improve compliance.

In which cases is Compression class 1 sufficient?

Prof. Stücker: Compression class 1 has a resting pressure of 18 to 21 mmHg and often suffices to alleviate symptoms as well as improve quality of life, which are the essential goals of compression therapy. You should always start with the lowest class and check whether problems can be alleviated. Class 1 stockings are not simply better thrombosis prevention stockings, as is often assumed, but actually suitable compression stockings with a significant effect. Studies[1] also show that they can be donned much more easily than Class 2 stockings.

What role do the new Guidelines relating to medical compression therapy play, and what are the rules for reimbursement?

Prof. Stücker: The Guidelines provide clear recommendations as to when circular knit or flat knit stockings should be used. They’re designed to be a reference document for physicians’ practices and medical supply retailers. The health insurance company generally has to approve in advance when flat knit stockings should be used for treatment. It’s then useful to specify that circular knit stockings are simply not possible from a technical point of view, which is often the case with obese legs as well as lipedema. Prescribing compression stockings and donning aids generally has no impact on the budget for medicines and therapeutic products.

[1] J. Goetz, E. Kaisermayer, H. Haase, M. Jünger, H. Riebe: Better wearing comfort of knee-length elastic compression stockings with an interface pressure of 18–21 mmHg compared to 23–32 mmHg in elderly people after a one day trial – influence of foot deformities, rheumatism and arthritis. Clin Hemorheol Microcirc. 2019; E. Kaisermayer: Dissertation at Greifswald University Hospital, 2016.