Foot ulcer

What is a foot ulcer, and how common is it?

A foot ulcer is an open sore or break in the skin of the foot that is slow to heal¹². It may be shallow, in the top layer of skin, or reach deep into the tissue². Pressure, diabetes, nerve damage, poor blood supply, injury or rubbing can all cause one¹. About 6.3% of people with diabetes have a foot ulcer at any one time³. Rates of foot ulcers in adults with diabetes vary around the world³.

What causes a foot ulcer, and who gets one?

Foot ulcers usually have several causes acting together⁴. Neuropathy (nerve damage) is the most important cause⁴: loss of feeling means minor injuries or infection may go unnoticed⁵. Deformities such as hammer toes create pressure points that lead to calluses and ulcers⁵. Poor circulation (peripheral artery disease) is a contributing cause in about one-third of foot ulcers, and is present in up to about half of diabetic foot ulcers⁴⁵. People with diabetes who are older or have had it longer are more often affected, though age and length of time with diabetes may not directly cause the ulcer³⁶.

What does a foot ulcer look like, and how is it diagnosed?

The most common sign is an open sore that doesn't heal, often with redness, swelling, pain or tenderness². It can also be hidden under thick, discoloured callus². Foot problems may not hurt, so checking your feet every day helps spot problems early⁷. A podiatrist or doctor checks feeling in your foot, your circulation, the wound and how deep it goes⁵⁸⁹. If you have diabetes or a slow-healing sore, you can ask for sensation and circulation tests.

What helps a foot ulcer heal?

For people with diabetes who have a plantar forefoot or midfoot ulcer from nerve damage, without poor circulation or infection, taking pressure off the ulcer (offloading) is arguably the most important step in healing, with a non-removable knee-high device as first choice and a removable knee-high or ankle-high device as second choice if a non-removable device is not suitable or not tolerated¹⁰¹¹. Regular removal of dead or unhealthy tissue (debridement) and wound care are also very important⁵¹². Offloading devices or footwear are worn as the podiatrist instructs, wound care visits are attended regularly because debridement and dressing changes are part of treatment, and the multidisciplinary team may include podiatry, vascular, orthotics and diabetes care. Ulcers with poor circulation or infection need the team's assessment first¹⁰¹¹.

What if standard care isn't enough?

Add-on treatments, such as special dressings or oxygen therapy, are specialist decisions that follow offloading, infection control and a circulation check¹². Ask whether circulation has been checked.

What's the outlook, and how can I stop it coming back?

Ulcers often come back in adults with diabetes: about 40% within a year of healing¹³. Some people need an amputation¹⁴. Your own outlook depends on your health, circulation and care¹³¹⁵¹⁶.

Keep going to foot checks at the interval your clinician sets, even after healing¹¹¹⁷, and ask about suitable footwear.

What can make it serious?

• An infection is getting worse, with more pain, redness, swelling or pus, but the redness isn't spreading and you feel well.
• A wound or sore on your foot or leg hasn't started to heal after two weeks, or keeps coming back.
• Your foot ulcer is being treated but isn't getting better (ask about a review by the foot team).
• Redness from a wound, sore or infection is spreading into your foot or leg, or red streaks run up from it.
• You have a foot wound, ulcer or infection, or a red, hot, swollen foot, and also have a fever, chills, a fast heartbeat or feel unwell.
• Your foot, or a patch of skin on your foot or leg, becomes red, hot, swollen and painful.
• You have diabetes or poor circulation and signs of infection in your foot, toe or nail, such as redness, warmth, swelling, pus, a bad smell or more pain.
• You have diabetes or poor circulation and a foot infection that is spreading fast, with a fever, and you feel very unwell.
• You have diabetes, poor circulation or reduced feeling in your feet and notice a new wound, sore, blister or colour change on your foot, or a sore that isn't healing.
• You have diabetes and a foot problem, and you also feel unwell, or your foot swells quickly.
• You have diabetes or reduced feeling in your feet and one foot becomes red, hot or swollen, or suddenly changes shape, even if it doesn't hurt (possible Charcot foot).
• You have constant pain in your foot or toes that is worse at night or when your legs are raised, and eases when you hang your leg down (this can be a sign of poor circulation).
• The skin on your toes or foot turns dark or black, or a wound turns black and smells bad.
• You have pain in a bone with a fever.
• You have a foot wound, ulcer or infection and also feel very unwell, with confusion or slurred speech, severe shivering or muscle pain, severe breathlessness, mottled or discoloured skin, or little or no urine (possible sepsis).