The main difference between TED hosiery and other compression garments has to do with the way they apply pressure to the leg. Compression socks, especially graduated compression socks, push blood and waste fluid from the feet towards the heart. Anti-embolism stockings—also called thrombo-embolic deterrent hose or TED hose— provide pressure, but do so with less force and often without an upward directional thrust.
Both compression socks and anti-embolism stockings help to prevent deep vein thrombosis (DVT) and pulmonary embolism. Whereas compression socks work well for people who are able to walk around, TED hose reduce the risk of DVT for non-ambulatory patients.
Typically, anti-embolism stockings offer uniform compression with a pressure level less than 20 mmHg. Since bedridden patients stay in a reclining position, they usually do not need graduated compression, which works against gravity by exerting pressure up the leg. While compression socks and anti-embolism stockings both reduce the risk of blood clots and DVT, anti-embolism stockings are designed to be worn during times of decreased mobility such as a period immediately following sclerotherapy, endovenous ablation, phlebectomy, or any major surgery. ("Anti-Embolism") As a patient regains mobility after surgery, graduated compression socks typically become the more appropriate choice for preventing DVT. In fact, the North American Thrombosis Forum (NATF) recommends, "Patients may wear TED hose for up to three weeks, at which time they are mobile once again or have been prescribed a different treatment..."
What Is Graduated Compression?
Graduated compression garments provide pressure on a gradient, with the most pressure at the ankles and the least pressure at the calves. For that reason, the strength of a graduated compression sock is described using a pressure range, rather than a single measurement. For example, a mild, graduated compression sock measures 15-20 mmHg. This means that sock exerts 20 millimeters of mercury at the ankle and 15 millimeters of mercury at the calf. (For context, normal diastolic blood pressure measures 80 millimeters of mercury.) While this pressure pattern pushes blood from the ankle to the calf, the blood flows in the same direction inside the veins. The sock assists the veins as they move blood and lymphatic fluid from the lower extremities towards the heart.
For anyone standing or sitting for long periods, blood often pools in the lower limbs and feet. This can cause swelling and pain. When you wear knee-high graduated compression stockings, the force of the compression gradient helps to stop blood and waste fluid from stagnating in the lower legs. In contrast, most TED hose do not apply graduated pressure and, if they do, they provide more pressure to the calf. Because of this,TED hose are ideal for someone reclining in a bed.
TED hose often provide uniform pressure throughout the sock, which means that the thickest part of the leg receives the most pressure. According to the NATF, "TED hose help reduce th[e] risk [of clots] by administering pressure on the lower part of the leg and feet—with the most compression occurring at the calf muscle. An anti-embolism stocking is designed for those patients lying in bed, immobile, and it prevents blood from pooling in the calf. This body part is a particularly vulnerable area for bedridden patients, the NATF website explains: “As patients lay in bed, blood is more likely to pool in the calf, creating the right environment for a clot to form."
What Is Deep Vein Thrombosis?
DVT occurs when a blood clot forms in the deep veins, typically in the legs. Another name for DVT is venous thrombosis. Although symptoms—including swelling, pain, a feeling of warmth, or red skin—may accompany a deep vein blood clot, the condition can also develop without any noticeable signs. Unfortunately, DVT often leads to more serious medical complications. Venous thromboembolism describes a blood clot breaking off and traveling through the circulatory system to block another vessel. For example, when a blood clot blocks a blood vessel in the lung, the resulting pulmonary embolism can be fatal. Another condition, called post-thrombotic syndrome or postphlebitic syndrome causes long-term damage to the veins. ("Deep Vein")
According to the Mayo Clinic, risk factors that make people more susceptible to DVT and its downstream complications include:
- Inheriting a blood-clotting disorder.
- Prolonged bed rest, such as during a long hospital stay, or paralysis.
- Injury or surgery.
- Pregnancy.
- Birth control pills (oral contraceptives) or hormone replacement therapy.
- Being overweight or obese.
- Smoking.
- Cancer.
- Heart failure.
- Inflammatory bowel disease.
- A personal or family history of deep vein thrombosis or pulmonary embolism.
- Age.
- Sitting for long periods of time, such as when driving or flying.
Of all of the risk factors listed above, TED hose are most appropriate for just two groups: people observing prolonged bed rest and those recovering from injury or surgery. All of the other at-risk groups would typically be better served by graduated compression socks or stockings.
Both TED hose and graduated compression socks promote healthy blood flow, which prevents blood clots from forming; however, TED hose are designed to be worn in bed. Graduated compression socks, on the other hand, should never be worn in bed.
Some medical conditions, such as diabetes and heart failure, can contraindicate the use of medium-strength or high-strength compression socks. Consult your doctor if you're worried about developing a deep vein blood clot. A medical professional, someone able to review your medical record, can advise you about the form of compression therapy that will work best for you.
Is There a Difference Between Hosiery and Sock Material?
You might imagine that one major difference between TED hose and compression socks would have to do with the material used to manufacture them. In reality, evidence suggests that the mmHg measurement of compression garments has a greater impact on efficacy than material composition. In a 2013 study of sports compression garments, researchers determined, "No clear relationship between percentage of fabrics composition and generated pressure was established." (Troynikov 160-161) The fabric composition—whether you're wearing a garment made of pantyhose material, merino wool, or a high-tech antimicrobial blend—doesn't have the same influence on compression as the mmHg rating does.
Many doctors use the terms "compression hosiery," "compression stockings," and "compression socks" interchangeably. Ultimately, with a graduated compression garment, the material matters less than the compression range, so the distinction between a "stocking" and a "sock" is arbitrary. As a result, many people assume that the terms "TED stockings" and "compression socks" refer to the same type of garment. This is untrue. Anti-embolism stockings work differently because they deliver a lower pressure throughout the leg, and they do not have the same pressure gradient. While both garments promote venous return and reduce blood pooling, they have different intended patients.
Additional Benefits of Compression Socks
Graduated compression therapy introduces additional benefits beyond reducing the risk of blood clots, pulmonary embolism, and post thrombotic syndrome. Below, we've listed some complaints that can be managed with the regular use of graduated compression therapy.
Chronic Venous Insufficiency
Chronic venous insufficiency (CVI) occurs when the walls and valves within the vein no longer function normally. As pressure builds inside a veins, from venous stasis, leg swelling, or injury, the blood begins flowing backwards through one-way valves. Once these valves fail, varicose veins and spider veins can form. Varicose veins appear bulbous and blue, and spider veins create a red or purple web on the surface of the skin.
In an interview with University of Utah, vascular surgeon Dr. Claire Griffin explains, "Compression socks help prevent the backup of blood, which is what leads to incompetent veins, and incompetent veins is what leads to varicose veins." ("Compression") Although a spider or varicose vein cannot be cured without surgery or an outpatient medical procedure, compression socks do work to reduce the symptoms. Griffin confirms, "They make a difference, and often people notice an immediate symptomatic improvement in how their legs feel at the end of the day."
Lymphedema
Lymphedema is a medical condition caused by damaged or dysfunctional lymph nodes. Causes include cancer treatment, infection, and even congenital predisposition. The damaged or missing lymph nodes cannot drain lymphatic waste fluid normally. Improper drainage results in swelling, infections, and, in some cases, soft tissue cancer. ("Lymphedema")
While there is no cure for lymphedema, it can be treated by manually reducing the buildup of lymphatic fluid in the limbs. To maintain a long-term reduction in leg volume, doctors often recommend graduated compression socks. In a review of the medical literature, doctors Chung Sim Lim and Alun H. Davies explain, "Generally, the highest level of compression (20–60 mm Hg) that the patient can tolerate is likely to be the most beneficial. However, lower compression can be used for milder lymphedema or general leg edema." (E396)
Edema
Edema, or swelling, can have many different causes. As an example, a broken bone may cause edema. Compression socks can help to alleviate the symptoms of two forms of chronic edema: peripheral edema (swelling of the lower legs) and pedal edema (swelling of the feet). For these types of edema, compression socks have been shown to prevent swelling and reduce discomfort.
In some cases, advanced edema causes stretched, shiny skin and ulcers. Compression garments have also been shown to relieve these secondary symptoms. For example, a 2019 study concluded, "The available evidence shows that, compared with usual care, compression stockings are effective in preventing venous leg ulcer recurrence and likely to be cost-effective." (Health) Beyond relieving pain and reducing swelling, compression therapy also helps to prevent problems that result from edema, like ulcers and skin changes.
Aches, Pains, and Oxidative Stress
People who have jobs that require them to stand or sit all day often complain of soreness in the lower extremities, leg fatigue, leg pain, plantar fasciitis, or pain in the feet. A seated posture is linked to a number of health problems, especially when such a posture is maintained for many hours at a time. In a review of the existing scientific literature on occupational sitting, researchers summarize that, "...Recent studies...have demonstrated associations of sitting time with obesity, metabolic syndrome and diabetes, markers of cardiovascular disease risk, and premature mortality." (van Uffelen) Whenever someone sits for prolonged periods, evidence indicates that the behavior can negatively impact their health. By promoting healthy blood flow, compression socks help reduce the aches and pains associated with long periods of sitting.
Another study, published in Occupational Medicine, examined healthcare workers and suggested that standing for long periods may result in dangerous accumulation of reactive oxygen species (ROS) in the bloodstream. The researchers write, "Healthy workers who stand for >90% of their working time have increased production of ROS which is reversed through the use of compression stockings." (Flore 340) Oxidative stress, caused by high levels of ROS, can become toxic to cells and has been associated with systemic diseases like atherogenesis, chronic venous insufficiency, and even cancer. Compression socks reduce the accumulation of ROS in the lower limbs, thereby reducing the risk of major health problems. The study concluded: "The use of compression stockings should be considered in workers who stand for prolonged periods when other preventive measures such as breaks and posture change are not possible."
By improving blood circulation, compression socks leave your legs feeling energized. Even after a long work shift sitting or standing, graduated compression prevents blood from pooling in the lower legs. This reduces feelings of heaviness, fatigue, and discomfort. Additionally, evidence suggests that compression socks can help aid in muscle recovery. (Ali) When you forget to wear compression socks, opting for compression therapy after a long period of sitting or standing may help sore muscles recover faster.
Stocking Length
Both graduated compression stockings and anti-embolism stockings are considered support stockings, and they’re available in a thigh-high or knee-high style. A review published in the British Journal of Nursing determined that thigh-length and knee-length TED anti-embolism stockings were equally effective, although the shorter stockings proved more cost-effective and resulted in better patient compliance.
Like compression hose, stockings, and socks, TED hose are also available in a gradient compression style. When it comes to knee-length, gradient compression TED hose, the main difference from other types of medical compression stockings is the compression level. As Lim and Davies explain, "Although the terms 'antiembolism stockings' and 'graduated compression hosiery' are often used interchangeably and both types of stockings offer graduated compression, they have different levels of compression and indications." (E392)
Even if you find TED hose in a knee-length, gradient style, they will probably have a higher calf-to-ankle ratio than a compression sock within the same pressure range. Aside from that difference, anti-embolism stockings can be worn in bed, 24 hours a day. Compression socks should never be worn in bed. Plus, you won't find an anti-embolism stocking that exerts more than 20 mmHg, whereas health care providers often prescribe high-compression stockings with pressures up to 60 mmHg.
We recommend knee-length 15-20 mmHg and 15-25 mmHg compression socks for most ambulatory people hoping to prevent blood clots. These pressure ranges are comfortable enough to wear every day and strong enough to provide real medical benefits. For bedridden patients, we recommend working closely with a doctor to find the right anti-embolism stockings to suit your needs.
Sources:
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“Anti-Embolism Socks: for Safety's Sake (after Surgery).” Atlanta Vascular & Vein Center, 12 Jan. 2018, http://atlantavascularandveincenters.com/anti-embolism-socks-safetys-sake-surgery/.
“Compression socks can help prevent varicose veins.” The Scope, University of Utah, Jan 10, 2018, https://healthcare.utah.edu/the-scope/shows.php?shows=0_u6yd3xaw.
“Deep Vein Thrombosis (DVT).” Mayo Clinic, Mayo Foundation for Medical Education and Research, 6 Mar. 2018, https://www.mayoclinic.org/diseases-conditions/deep-vein-thrombosis/symptoms-causes/syc-20352557.
Flore, R., Gerardino, L., Santoliquido, A., Catananti, C., Pola, P., and Tondi, P. "Reduction of oxidative stress by compression stockings in standing workers." Occupational Medicine, vol. 57, iss. 5, Aug. 2007, pp. 337–341, https://academic.oup.com/occmed/article/57/5/337/1404908.
Health Quality Ontario. “Compression Stockings for the Prevention of Venous Leg Ulcer Recurrence: A Health Technology Assessment.” Ontario Health Technology Assessment Series Vol. 19, Iss. 2, pp. 1-86. 19 Feb. 2019, https://www.ncbi.nlm.nih.gov/pubmed/30828407.
Ingram, J.E. "A review of thigh-length vs knee-length antiembolism stockings." British Journal of Nursing, Vol. 12 Iss. 14, Jul. 1, 2003, pp. 845-851, https://www.magonlinelibrary.com/doi/abs/10.12968/bjon.2003.12.14.11408.
"Lymphedema." Mayo Clinic, Mayo Foundation for Medical Education and Research, 21 Dec. 2017, https://www.mayoclinic.org/diseases-conditions/lymphedema/symptoms-causes/.
Lim, Chung Sim and Alun H. Davies. “Graduated compression stockings.” CMAJ. Vol. 186, Iss. 10 pp. E391-E398. July 08, 2014, https://www.cmaj.ca/content/cmaj/186/10/E391.full.pdf.
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Troynikov, Olga, et al. “Influence of Material Properties and Garment Composition on Pressure Generated by Sport Compression Garments.” Procedia Engineering, vol. 60, 2013, pp. 157–162. ScienceDirect, https://www.sciencedirect.com/science/article/pii/S1877705813011053.
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