Offloading devices

What are offloading devices, and how do they work?

Offloading devices are casts, boots, shoes and similar devices that take pressure off part of your foot, usually a sore or ulcerated area. They help ulcers heal, and help stop them forming or coming back¹. Clinicians call this offloading, and you may also hear it called pressure relief.

Extra pressure under the sole is one of the main causes of diabetic foot ulcers², so a device moves weight away from the sore spot. The best-known example is the total contact cast (TCC), an enclosed cast usually applied from toe to knee, which shifts weight onto your leg³. A device only works by taking weight off, so it needs to be worn as directed.

What are offloading devices used for, and how well do they work?

They're best proven for healing ulcers on the sole of the foot, at the front or middle of the foot, in adults with diabetes who have lost feeling in their feet (neuropathy). A cast that can't be removed is the first choice⁴⁵.

On average, neuropathic ulcers treated with a cast heal in about 6 weeks⁶, and uncomplicated ulcers on the sole in 6 to 8 weeks with good offloading⁷. Healing slower than this is worth reviewing with your podiatrist. How well it works depends heavily on wearing the device: even the best one won't work if it isn't worn⁵.

Once an ulcer has healed, therapeutic footwear that relieves pressure, and that you actually wear, helps stop ulcers coming back⁸. For heel ulcers, ulcers on the top or sides of the foot, ulcers with infection or poor blood supply, and preventing a first ulcer, how well offloading works isn't clear yet⁸.

Is an offloading device right for me?

A non-removable knee-high device (a TCC or an instant TCC) suits adults with diabetes and an ulcer on the sole when you can tolerate it and your foot fits it safely⁹. It isn't suitable with a soft tissue infection, an infection in the bone, severe blood vessel disease or severe swelling of the lower leg or foot¹⁰. If you have reduced blood flow to your legs (peripheral arterial disease), a cast needs a check of your blood supply first, plus close follow-up¹¹.

A cast also reduces your mobility, and you can't check the ulcer yourself each day¹⁰. Some people can't work while wearing one¹². It's worth talking through your daily routine with your podiatrist first. Children, people without diabetes, and people with heel, infected or poor-circulation ulcers need individual advice from a podiatrist or high-risk foot service⁸.

What happens when I have one?

A podiatry team applies a cast in about 20–30 minutes, usually from toe to knee³. You're usually seen weekly to have it taken off, your foot checked, and the cast put back on if needed. Treatment can take many months³.

While it's on, keep it dry (a waterproof cast protector can help) and never take it off yourself³. You won't be able to travel by aeroplane in a cast¹². People with neuropathy may not feel the cast rubbing, so checking the skin matters³.

With a removable device, wearing it for at least 80% of your daily activity is what makes it effective¹³. In practice, that means wearing it for almost all the time you're on your feet.

What are the risks and side effects?

Casts can rub and cause new sores on your foot or leg¹², and with neuropathy you may not notice³. Compared with footwear, casts have more device-related problems, mainly damage to the cast and skin problems. They're about the same as removable walkers¹³. Keeping the cast clean, dry and protected helps lower these problems¹³.

Rarely, reduced movement and weight-bearing in a cast can lead to a blood clot in the leg (deep vein thrombosis) or in the lungs (pulmonary embolism)³¹². The signs to watch for are in the last section below.

How do offloading devices compare with other options?

A non-removable knee-high device heals more ulcers than removable devices¹⁰. How big that difference is isn't fully settled, because some reviews suggest removable devices may do as well¹³. If a non-removable device isn't suitable or you can't tolerate it, the next choices are a removable knee-high device, then a removable ankle-high device⁴⁵. Therapeutic footwear is a last resort when no device can be tolerated or reached⁹, and ordinary footwear alone isn't effective for healing⁷.

Surgery is only considered if non-surgical offloading fails to heal a forefoot ulcer. It tends to add modest benefit, with more side effects and higher costs⁴⁹. The best choice also depends on what you'll actually wear.